Untitled Quiz

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Questions and Answers

What is released into the atmosphere when certain materials burn?

It uses oxygen in the process of burning

It is extracted from deep inside the Earth

It releases harmful gases into the atmosphere (correct)

It is hard to transport

The three Rs that will help us to conserve natural resources for long-term use are:

Reduce, regenerate, reuse

Reduce, recycle, reuse (correct)

Recycle, regenerate, reuse

Reduce, reuse, redistribute

Which of these is an example of sustainable development?

Finding alternate fuel reservoirs

Clearing forests to set up new industries

Planning for safe disposal of wastes after mining (correct)

Cleaning water resources

Which of the following is not a natural resource?

Wooden house Signup and view all the answers

In which year was the Wildlife Protection Act implemented in India?

1972 Signup and view all the answers

Who prepared the Ganga Action Plan?

Department of Environment Signup and view all the answers

At which of the following places are royal Bengal tigers found?

Sundarban delta Signup and view all the answers

In which of the following states does the Ganga originate?

Uttarakhand Signup and view all the answers

How can the construction of a water harvesting system help a region?

It will reduce the occurrence of droughts Signup and view all the answers

Which of the following is not a natural resource?

Electricity Signup and view all the answers

Which one of the following is the Biosphere Reserve of India?

Nilgiri Signup and view all the answers

When was the Ganga Action Plan launched?

1986 Signup and view all the answers

The pH range most conducive for the life of freshwater plants and animals is:

6.5 to 7.5 Signup and view all the answers

Tropical rainforests grow well in areas receiving rainfall:

200 cm Signup and view all the answers

Electrolysis of water is an example of:

Decomposition reaction Signup and view all the answers

In which of the following reactions, there is an exchange of ions between the reactants?

Double displacement Signup and view all the answers

Burning of natural gas is an example of:

Exothermic reaction Signup and view all the answers

What are the substances that are oxidised and reduced in the reaction ZnO + C → Zn + CO?

C, ZnO Signup and view all the answers

The reaction between quicklime and water is an example of:

Combination and Exothermic Signup and view all the answers

Thermal decomposition of ferrous sulphate gives:

All of above Signup and view all the answers

Which one is not formed in the thermal decomposition of lead nitrate?

N₂ Signup and view all the answers

The colour of white silver chloride after placing it in sunlight for some time will be:

Grey Signup and view all the answers

Which of the following is a characteristic of a chemical reaction?

All of the above Signup and view all the answers

Human body works efficiently within the pH range:

Between 7.0 and 7.8 Signup and view all the answers

Our tooth decay starts when the pH of the mouth is:

Less than 5.5 Signup and view all the answers

Which of the following acid is secreted when nettle leaves sting?

Methanoic acid Signup and view all the answers

What is the nature of sodium chloride salt?

Neutral Signup and view all the answers

What is the nature of the salt produced by the reaction between a strong and a weak base?

Acidic Signup and view all the answers

What is the nature of the salt produced by the reaction between a weak acid and a strong base?

Basic Signup and view all the answers

Which of the following non-metallic oxides is neutral in nature?

Neutral Signup and view all the answers

Which of the following non-metallic oxides is neutral in nature?

H₂O Signup and view all the answers

What is the ratio of concentrated HNO3 to concentrated HCl in aqua regia?

1:3, respectively Signup and view all the answers

How many bonds can one carbon atom form in a compound with the electronic configuration of 2, 4?

4 Signup and view all the answers

What is the likely product represented by 'X' in the reaction CH4 + Cl2 → X?

CH3Cl + HCl Signup and view all the answers

Which functional group is present in the carbon compound represented in the following image?

Ketone Signup and view all the answers

What name should a carbon compound containing two atoms of carbon bear?

Ethane Signup and view all the answers

How does chlorine react to a hydrocarbon compound in the presence of sunlight?

It substitutes a hydrogen atom from the compound Signup and view all the answers

Which chemical compound represents a diluted form of ethanoic acid?

Vinegar Signup and view all the answers

What is the molecular formula of cyclobutane?

C4H8 Signup and view all the answers

How does a soap molecule interact with oil?

Carbonic chain end of the soap interacts with the oil Signup and view all the answers

Why do methane, ethane, and propane form a homologous series?

Differ from each other by a CH2 group Signup and view all the answers

Which of the following belongs to a homologous series of alkynes?

C3H4 Signup and view all the answers

Choose the correct statement regarding the ethene molecule.

All of the above. Signup and view all the answers

What is a property of ionic compounds?

Both (A) and (B) Signup and view all the answers

Which of the following is NOT a characteristic of fullerenes?

It contains only fused six-membered carbon-carbon rings Signup and view all the answers

How many single bonds are present in methane?

Four Signup and view all the answers

A hydrocarbon should have a minimum of _____ carbon atoms to show isomerism.

three Signup and view all the answers

Which of the following forms the basis of the modern periodic table?

Atomic number Signup and view all the answers

Which of the following is the most reactive element of group 17?

Fluorine Signup and view all the answers

What is the correct order of the atomic radii of the elements oxygen, fluorine, and nitrogen?

F < O < N Signup and view all the answers

Element X forms a chloride with the formula XCl2, which is solid with a high melting point. X would most likely be in the same group as:

Mg Signup and view all the answers

What happens to the electropositive character of elements on moving from left to right in a periodic table?

Decreases Signup and view all the answers

What is the other name for group 18th elements?

Noble gases Signup and view all the answers

Which group elements are called transition metals?

Group number 3 to 12 Signup and view all the answers

The electronic configuration of an element M is 2, 8, 4. In the modern periodic table, the element M is placed in:

14th group Signup and view all the answers

Which of the following elements has 2 shells, and both are completely filled?

Neon Signup and view all the answers

Which option describes the achievements of Mendeleev’s Periodic Table?

Prediction of noble gases Signup and view all the answers

As one goes from sodium to argon, how does the atomic radius of elements in the third period change?

Atomic radius decreases from sodium to argon Signup and view all the answers

Boron is a non-metal and is placed under group 13 and period 2. How can boron form bonds with other elements?

By sharing 3 electrons Signup and view all the answers

The current induced in the coil will change its direction continuously?

True Signup and view all the answers

Electronegativity is defined as the ability of an element to form bonds by gaining electrons. How does electronegativity vary across the periods?

It increases as more electrons are added to the same shell Signup and view all the answers

What is the order of the metallic character down the group?

It increases as electrons move away from the nucleus Signup and view all the answers

A soft iron bar is introduced inside a current-carrying solenoid. The magnetic field inside a solenoid will?

Will increase Signup and view all the answers

What is the trend of valency along the periods in the modern periodic table?

It increases and then decreases Signup and view all the answers

As the speed of the coil in the motor increases, there is a reduction in the current flowing through it. This assertion is?

Both (A) and (R) are correct but (R) is the correct explanation of (A) Signup and view all the answers

In amoeba, food is digested in the:

Food vacuole Signup and view all the answers

Which of the following correctly describes the magnetic field near a long straight wire?

The field consists of concentric circles centred on the wire Signup and view all the answers

Among the following statements regarding the solenoid, which one is incorrect?

The pattern of the magnetic field associated with the solenoid is different from a bar magnet. Signup and view all the answers

In which of the following groups of organisms are food materials broken down outside the body and absorbed?

Yeast, mushroom, bread mould Signup and view all the answers

What is the contraction and expansion movement of the walls of the food pipe called?

Peristaltic movement Signup and view all the answers

Why are appliances with metal bodies generally connected to the earthing wire?

To prevent the leakage of current Signup and view all the answers

Which process explains the energy extraction from a sea wave?

Using the kinetic energy of the waves to produce electricity Signup and view all the answers

What are the products obtained by anaerobic respiration in plants?

Ethanol + carbon dioxide + energy Signup and view all the answers

Why is wind energy considered a conventional source of energy?

As it is readily available and used for a long time Signup and view all the answers

When a few drops of iodine solution are added to rice water, the solution turns blue-black in color. What does this indicate?

Starch Signup and view all the answers

Should biogas be considered a ‘good’ source of energy?

Good, as it does not cause any harm to the environment Signup and view all the answers

What is the respiratory pigment in human beings?

Haemoglobin Signup and view all the answers

Which process would help extract energy from fossil fuels?

Burning Signup and view all the answers

What is the important characteristic of emphysema?

Destruction of the alveolar wall and air sacs in the lungs are damaged Signup and view all the answers

What are the characteristic processes observed in anaerobic respiration?

ii), iii), iv) only Signup and view all the answers

Which process explains the conversion of wind energy into energy for a water-lifting pump?

Conversion of the kinetic energy of wind into mechanical energy Signup and view all the answers

The opening and closing of the stomatal pore depend upon:

Water in the guard cells Signup and view all the answers

Why is biogas considered a 'good' source of energy?

As it burns without releasing smoke Signup and view all the answers

How do plants get rid of solid waste products?

Shedding of yellow leaves Signup and view all the answers

Should tidal energy be considered a conventional or non-conventional source of energy?

Non-conventional, as the extraction of this energy is possible with advances in technology Signup and view all the answers

Chemicals present in tobacco smoke lead to the breakdown of the elastic tissue in the alveoli. Name this specific condition.

Emphysema Signup and view all the answers

How does increased fuel efficiency benefit humans and the environment?

Pollution and consumption will decrease Signup and view all the answers

Digestion of food starts from which organ of the human digestive system?

Mouth due to the presence of saliva Signup and view all the answers

Why is a thermal power plant considered a bad source of energy?

As the burning of fossil fuel releases harmful gases Signup and view all the answers

Which source of energy should Rihaan use for cooking to avoid smoke production?

Electricity Signup and view all the answers

What is the percentage of oxygen in the expired air when a person is resting?

16% Signup and view all the answers

How is food transported from the phloem to the tissues according to plants’ needs?

Food is transported from the region where it is produced to other parts of the plants Signup and view all the answers

Which process explains the working of a geothermal power plant?

Use of thermal energy to produce electricity Signup and view all the answers

What is the correct sequence of body parts in the human alimentary canal?

Mouth → oesophagus → stomach → small intestine → large intestine Signup and view all the answers

Should hydropower plants be considered a ‘good’ or ‘bad’ source of energy?

Good, as it does not pollute the atmosphere Signup and view all the answers

What is the function of the pituitary gland?

To stimulate growth in all organs Signup and view all the answers

Which process explains the extraction of the sun’s energy to light a bulb?

Conversion of solar energy into electric energy Signup and view all the answers

Which option shows the correct order of events when a bright light is focused on our eyes?

Bright light → receptors in eyes → sensory neuron → spinal cord → motor neurons → eyelid closes Signup and view all the answers

Which characteristic helps us recognize a good source of fuel?

Produces a large amount of energy Signup and view all the answers

A female is suffering from an irregular menstrual cycle and is prescribed hormonal tablets. What hormone is likely lacking?

Oestrogen Signup and view all the answers

The decomposers in an ecosystem do what?

Convert organic material to inorganic forms Signup and view all the answers

How does the plant communicate the information of touch when the leaves of the 'touch-me-not' plant droop?

The plant uses electrical-chemical signals to transfer information from cell to cell. Signup and view all the answers

Which statement shows the interaction of an abiotic component with a biotic component in an ecosystem?

An earthworm making a burrow in the soil Signup and view all the answers

How will information travel within a neuron?

Dendrite -> cell body -> axon -> nerve ending Signup and view all the answers

Which of the following are environment-friendly practices?

All of the above Signup and view all the answers

The amount of energy that flows from one trophic level to another in a food chain is typically what percentage?

10% Signup and view all the answers

Which parts of the brain control blood pressure?

Pons, medulla, cerebellum Signup and view all the answers

What can be a likely advantage of hormones over electric impulses in signal transmission?

It is secreted by stimulated cells and reaches all cells of the body. Signup and view all the answers

Manufacturing Chlorofluorocarbons-free refrigerators helps to prevent ozone depletion by?

Reducing the release of CFCs that reacts with ozone molecules Signup and view all the answers

The primary consumers in an ecosystem are?

Herbivores Signup and view all the answers

Which of the following is responsible for the depletion of the ozone layer?

CFCs Signup and view all the answers

How do free oxygen atoms form at higher levels of the atmosphere?

By splitting molecular oxygen into free oxygen atoms in the presence of high-energy UV radiations Signup and view all the answers

The driving force of any ecosystem is?

Solar energy Signup and view all the answers

Kitchen wastes can be hygienically disposed of through?

Composting Signup and view all the answers

The environment includes?

All of these Signup and view all the answers

Which of the following is a linear arrangement of organisms?

Food chain Signup and view all the answers

An agricultural cropland is?

An artificial ecosystem Signup and view all the answers

What is the order of the waste management hierarchy, from most to least favoured?

Prevention-Reuse-Recycle-Disposal Signup and view all the answers

Problems of solid waste disposal can be reduced through?

Recycling Signup and view all the answers

An environment-friendly practice is?

Using CFLs at homes and offices Signup and view all the answers

Which of the following limits the number of trophic levels in a food chain?

Decrease in energy at higher trophic levels Signup and view all the answers

The cleaners of nature are?

Decomposers Signup and view all the answers

The ozone hole may cause?

All of these Signup and view all the answers

In a food chain, the third trophic level is always occupied by?

Carnivores Signup and view all the answers

The biotic components of an ecosystem consist of?

Producers, consumers & decomposers Signup and view all the answers

Which of the following could be incinerated?

Needle of the syringe Signup and view all the answers

The harmful chemical which is accumulating in human beings through the food chain is?

DDT Signup and view all the answers

Carnivores represent?

Secondary and tertiary consumers Signup and view all the answers

Which of the following constitutes a food chain?

Grass, goat and human Signup and view all the answers

Biodegradable wastes include?

Wood shavings Signup and view all the answers

What are the methods by which energy can be recovered from waste to energy?

By (1), (2) and (3) Signup and view all the answers

What is the most expensive component of solid waste handling?

Collection Signup and view all the answers

Which of the following statement regarding recycling is wrong?

Increases the need for mining virgin materials Signup and view all the answers

What is the main significance of sustainable development?

To preserve the natural resources for the needs of future generations Signup and view all the answers

The most rapidly dwindling natural resource in the world is?

Forest Signup and view all the answers

Which of these practices will help to conserve forests?

Putting a ban on deforestation Signup and view all the answers

Which of these practices can be adopted to save the environment?

Refuse the use of single-use plastic bags Signup and view all the answers

What is the disadvantage of using fossil fuels as energy sources?

Fossil fuels lead to environmental pollution and are non-renewable. Signup and view all the answers

Fruits are formed from the

Ovary Signup and view all the answers

Reproduction is essential for living organisms in order to ……………………

Continue the species generation after generation Signup and view all the answers

The male reproductive parts of a flower, the stamens, are collectively known as

Androecium Signup and view all the answers

Which of the following diseases is transmitted sexually?

Syphilis Signup and view all the answers

IUCD is for

Contraception Signup and view all the answers

Which among the following is not the function of the testes at puberty?

(iii) and (iv) Signup and view all the answers

Which of the following is a contraceptive?

All of these Signup and view all the answers

The correct sequence of organs in the male reproductive system for the transport of sperm is

Testis → vas deferens → urethra Signup and view all the answers

During adolescence, several changes occur in the human body. Mark one change from the following associated with sexual maturation in boys.

Cracking of voice Signup and view all the answers

AIDS is a deadly disease which is caused by

a virus Signup and view all the answers

Which among the following diseases is not sexually transmitted?

Hepatitis Signup and view all the answers

A population of thermophilic archaebacteria are generally found in hot springs. Any change to the temperature of the water affects the survival of the archaebacteria. If the temperature of hot springs gets reduced, change in which component can allow the survival of a few members of these archaebacteria?

Cell wall Signup and view all the answers

The process in which small portions of the oviducts of a woman are removed by surgical operation, and the cut ends are ligated is

tubectomy Signup and view all the answers

What conclusion can be made about the division in plasmodium?

The cell divides multiple times giving rise to many daughter cells. Signup and view all the answers

The ratio of the number of chromosomes in a human zygote and a human sperm is

2:1 Signup and view all the answers

How do spores develop into Rhizopus?

Spores divide and grow into a new individual Signup and view all the answers

Which event will likely occur in the ovaries of females after attaining puberty?

Production of eggs Signup and view all the answers

Which of the following options correctly shows the path that the sperms take when they are released from the male reproductive system?

testis → vas deferens → urethra → penis Signup and view all the answers

Mendel conducted his famous breeding experiments by working on the following:

Pisum Sativum Signup and view all the answers

Which section of DNA provides information for one protein?

Gene Signup and view all the answers

Which of the following is an example of genetic variation?

Two children have different eye colour Signup and view all the answers

In peas, a pure tall (TT) is crossed with a pure short plant (tt). The ratio of pure tall plants to pure short plants in the F2 generation is:

3:1 Signup and view all the answers

Humans have two different sex chromosomes, X and Y. Based on Mendel’s laws, a male offspring will inherit which combination of chromosomes?

A combination of X and Y chromosomes from either of its parents Signup and view all the answers

Two pea plants, one with round green seeds (RR yy) and another with wrinkled yellow seeds (rrYY), produce F1 progeny that have round yellow seeds (RrYy). When F1 plants are self-pollinated, the F2 progeny will have a new combination of characters. Choose the new combinations from the following:

(i) and (iv) Signup and view all the answers

Miller and Urey performed an experiment to prove the origin of life from organic compounds. The gases they took were:

methane, ammonia, hydrogen, water vapour Signup and view all the answers

Which of the following is a pair of analogous organs?

Wings of a pigeon and a bat Signup and view all the answers

Two pink-coloured flowers on crossing resulted in 1 red, 2 pink, and 1 white-flower progeny. The nature of the cross will be:

cross-fertilization Signup and view all the answers

A zygote which has an X chromosome inherited from the father will develop into a:

girl Signup and view all the answers

The surprise products formed in the experiment conducted by Miller and Urey were:

amino acids Signup and view all the answers

From the list given below, select the character which can be acquired but not inherited.

Size of body Signup and view all the answers

In humans, if gene B gives brown eyes and gene b gives blue eyes, what will be the colour of the eyes of the person having combination (i) Bb and (ii) BB?

(i) Brown (ii) Brown Signup and view all the answers

What is the probability that the male progeny will be a boy?

50 % Signup and view all the answers

Which of the following does Darwin’s theory not include?

Evolution Through Inheritance Signup and view all the answers

In pea plants, yellow seeds are dominant to green seeds. If a heterozygous yellow-seeded plant is crossed with a green-seeded plant, what ratio of yellow and green-seeded plants would you expect in the F1 generation?

50:50 Signup and view all the answers

Which of the following statements is not true with respect to variation?

All variations in a species have equal chances of survival. Signup and view all the answers

The two versions of a trait (character) which are brought in by the male and female gametes are situated on:

Copies of the same (homologous) chromosomes Signup and view all the answers

Exchange of genetic material takes place in:

Sexual reproduction Signup and view all the answers

When a plane mirror is rotated through a certain angle, the reflected ray turns through twice as much, and the size of the image:

remains the same Signup and view all the answers

If an object is placed symmetrically between two plane mirrors, inclined at an angle of 72 degrees, then the total number of images formed is:

4 Signup and view all the answers

Which statement is true for the reflection of light?

The angle of incidence and reflection are equal. Signup and view all the answers

The focal length of a plane mirror is

infinite Signup and view all the answers

A beam of light incident on a plane mirror forms a real image on reflection. The incident beam is:

convergent Signup and view all the answers

An object is placed at a distance of 40 cm in front of a concave mirror of a focal length of 20 cm. The image produced is:

real, inverted and of the same size as that of the object Signup and view all the answers

A student conducts an experiment using a convex lens. He places the object at a distance of 60 cm in front of the lens and observes that the image is formed at a distance of 30 cm behind the lens. What is the power of the lens?

5 dioptre Signup and view all the answers

An image of an object produced on a screen, which is about 36 cm using a convex lens. The image produced is about 3 times the size of the object. What is the size of the object?

12 cm Signup and view all the answers

Image formed by a convex spherical mirror is:

virtual Signup and view all the answers

A student studies that a convex lens always forms a virtual image irrespective of its position. What causes the convex mirror to always form a virtual image?

Because the reflected ray never intersects Signup and view all the answers

A 10 mm long awl pin is placed vertically in front of a mirror. The image is formed at 30 cm in front of the mirror. What is the focal length of this mirror?

-20 cm Signup and view all the answers

Rahul conducts an experiment using an object of height of 10 cm and a concave lens with a focal length of 20 cm. The object is placed at a distance of 25 cm from the lens. Can the image be formed on a screen?

No, as the image formed will be virtual Signup and view all the answers

Magnification produced by a rearview mirror fitted in vehicles:

is less than one Signup and view all the answers

A student conducts an activity using a concave mirror with a focal length of 10 cm. He placed the object 15 cm from the mirror. Where is the image likely to form?

At 30 cm in front of the mirror Signup and view all the answers

The image of an object placed in front of a convex mirror is formed at

behind the mirror Signup and view all the answers

A full length of the image of a distant tall building can definitely be seen using:

a convex mirror Signup and view all the answers

A student conducts an activity using a flask of height 15 cm and a concave mirror. He finds that the image formed is 45 cm in height. What is the magnification of the image?

Which of the following can make a parallel beam of light from a point source incident on it?

Concave mirror as well as convex lens Signup and view all the answers

What causes the difference in the speed of light in air and a glass slab?

Difference in density Signup and view all the answers

Which defect is likely if a person's eye lens curvature is increasing?

Myopia Signup and view all the answers

How does the pupil regulate the light entering the eye when a person exits a dark room into sunlight?

The size of the pupil will decrease, and less light will enter the eye Signup and view all the answers

Where does most refraction occur when light rays enter the eye?

The outer surface of the cornea Signup and view all the answers

In which part of the human eye is the image of an object formed?

Retina Signup and view all the answers

Why can danger signals installed at the top of tall buildings be easily seen?

Red light is scattered the least by smoke or fog Signup and view all the answers

Which phenomena of light are involved in the formation of a rainbow?

Refraction, dispersion and total internal reflection Signup and view all the answers

What changes occur in a person's eyes when seeing an object closer?

The ciliary muscles will contract Signup and view all the answers

The splitting of white light into different colors on passing through a prism is called what?

Dispersion Signup and view all the answers

The deflection of light by minute particles and molecules of the atmosphere in all directions is called ____________ of light.

scattering Signup and view all the answers

Which phenomenon contributes to the reddish appearance of the sun at sunrise or sunset?

Scattering of light Signup and view all the answers

Why do stars appear to twinkle at night?

Because the light of stars travels in a different medium Signup and view all the answers

What happens when white light enters a prism?

It splits into its constituent colors due to different refractive indices Signup and view all the answers

When white light enters a glass prism from the air, the angle of deviation is least for which color?

Red light Signup and view all the answers

Which option justifies that the sun appears red at sunrise and sunset?

Red has a high wavelength, so it travels a longer distance Signup and view all the answers

At noon, why does the sun appear white?

Light is least scattered Signup and view all the answers

Twinkling of stars is due to atmospheric what?

Refraction of light by different layers of varying refractive indices Signup and view all the answers

What will be the colors of X, Y, and Z in the dispersion of white light in a prism?

X: violet; Y: green; Z: red Signup and view all the answers

What is the least resistance obtained by using 2 Ω, 4 Ω, 1 Ω, and 100 Ω in combination?

< 1 Ω Signup and view all the answers

What is the potential difference if 14 J of work is done to move 2 C charge?

7 V Signup and view all the answers

What type of fuse wire should be used if it repeatedly gets burnt with a heater?

More radius Signup and view all the answers

What will indicate the current in a circuit with a charge of 2C moving in 3s?

Ammeter will show a current of 0.7 A Signup and view all the answers

What does electrical resistivity of a metallic wire depend on?

Nature of the material Signup and view all the answers

What physical quantity remains the same between two points A and B when devices are connected in parallel?

Voltage Signup and view all the answers

The unit of electric power can also be expressed as what?

Kilowatt-hour Signup and view all the answers

What is the relationship between resistance and current?

They are inversely related to each other Signup and view all the answers

If a current of 1 A is drawn by a filament for 16 seconds, how many electrons pass through?

10^20 Signup and view all the answers

How much more heat is produced if the current is doubled?

Four times the original amount Signup and view all the answers

Which of the following represents voltage?

Work done / Current × Time Signup and view all the answers

What is the rating of the fuse to be used for a 1500 W cooler and a 500 W fan at 200 volts?

10 A Signup and view all the answers

Which combination of a 2 Ω resistor and a 4 Ω resistor offers the least resistance?

Parallel combination, which results in a net resistance of 0.5 Ω Signup and view all the answers

What is the heat dissipated by a 4 Ω resistor in a circuit with a series connection and a 6 V battery?

20 J Signup and view all the answers

To reduce electricity consumption at home, what kind of appliance should one purchase?

One which draws low power Signup and view all the answers

If n resistors each of resistance R are connected in parallel, what is their equivalent resistance?

R/n Signup and view all the answers

Which bar has greater resistivity: a bar of an alloy of 2 kg or a 3 kg iron bar of the same dimension?

Alloy bar because it has different types of atoms Signup and view all the answers

If two resistors connected in series give an equivalent resistance of 10 Ω and when connected in parallel give 2.4 Ω, what are the individual resistances?

6 Ω and 4 Ω Signup and view all the answers

A battery of 10 volts carries 20,000 C of charge through a resistance of 20 Ω. What is the work done in 10 seconds?

2 × 10^5 joule Signup and view all the answers

What will be the ratio of the resistances of two bulbs rated 40W, 220V and 60W, 220V?

3:2 Signup and view all the answers

If R1 and R2 be the resistance of the filaments of a 40W and 60W bulb, respectively, operating at 220V, which is the correct statement?

R2 < R1 Signup and view all the answers

How much does it cost to operate a 200 W toaster for 10 days at Rs. 5 per kWh?

Rs. 20 Signup and view all the answers

What happens to the power consumption if a coil in a heater is cut into halves and joined in parallel?

4 P Signup and view all the answers

What is the most suitable material for making the core of an electromagnet?

Soft iron Signup and view all the answers

Which of the following is not attracted by a magnet?

Brass Signup and view all the answers

When a straight conductor is carrying current, what is around it?

There are circular magnetic field lines around it Signup and view all the answers

What will a plotting compass placed near the south pole of a bar magnet do?

Point towards the south pole Signup and view all the answers

What is true about two magnetic field lines?

Never intersect each other Signup and view all the answers

If the front face of a circular loop of wire is the North Pole, which direction will the current flow?

Anticlockwise Signup and view all the answers

Which statement regarding magnetic field lines is incorrect?

If magnetic field lines are parallel and equidistant, they represent zero field strength. Signup and view all the answers

What is the magnetic field inside a long straight solenoid carrying current?

Is the same at all points Signup and view all the answers

What happens to the magnetic lines of force around a strong bar magnet placed vertically above a board?

In all the planes around the magnet Signup and view all the answers

The strength of the magnetic field inside a long current-carrying straight solenoid is:

Same at all points Signup and view all the answers

Which option explains Fleming’s left-hand rule for understanding the working of a motor?

When a current-carrying conductor is placed in a magnetic field, it experiences a force from the magnetic field. Signup and view all the answers

What is the formula for the force on a current-carrying conductor when placed perpendicular in a uniform magnetic field?

F=BIL Signup and view all the answers

What happens if a student inserts a bar magnet into a coil?

The galvanometer connected to the coil will show deflection indicating induced current. Signup and view all the answers

Magnesium ribbon is rubbed before burning because it has a coating of?

Basic magnesium carbonate Signup and view all the answers

Sodium and chlorine react to form sodium chloride, also called table salt. What options give the reactants and products of the reaction?

Reactants – sodium and chlorine; products – sodium chloride Signup and view all the answers

Which of the following options gives the chemical equation for the formation of aluminum chloride from aluminum and chlorine?

2Al + 3Cl2 → 2AlCl3 Signup and view all the answers

Give the ratio in which hydrogen and oxygen are present in water by volume.

2:1 Signup and view all the answers

A researcher adds barium hydroxide to hydrochloric acid to form a white-colored barium chloride. Which of the following options gives the balanced chemical equation of the reaction?

2HCl + Ba(OH)2 → BaCl2 + 2HOH Signup and view all the answers

One of the following processes does not involve a chemical reaction:

Melting of candle wax when heated Signup and view all the answers

The chemical formula of magnesium oxide is ______.

MgO Signup and view all the answers

From the following, which one is an example of a chemical reaction?

All of the above Signup and view all the answers

A student adds lead and silver to two different test tubes containing an equal amount of copper sulfate solution. The student observes that the color of the solution in the test tube with lead changes. What explains the change in the color of the solution?

A displacement reaction takes place as lead replaces copper from the solution. Signup and view all the answers

Which of the following reactions is used in black-and-white photography?

Decomposition Reaction Signup and view all the answers

What happens when lead nitrate reacts with potassium iodide?

Yellow ppt of lead iodide and potassium nitrate will be produced Signup and view all the answers

The chemical reaction between potassium chloride and silver nitrate is given by the chemical equation, AgNO3 + KCl → AgCl + KNO3. What can be inferred from the chemical equation?

Silver nitrate and potassium undergo a double displacement reaction to form silver chloride and potassium nitrate. Signup and view all the answers

Which of the following shows an oxidation reaction?

Gain of oxygen Signup and view all the answers

Formation of carbon disulfide from carbon and sulfur takes place by?

Absorption of heat Signup and view all the answers

The metal which is liquid at room temperature is?

Mercury Signup and view all the answers

Which of the following are exothermic processes?

(i) Reaction of water with quick lime Signup and view all the answers

Which of the following reaction can also be termed a thermal decomposition reaction?

Decomposition reaction Signup and view all the answers

Oxidation is a process which involves?

Addition of oxygen Signup and view all the answers

The process of reduction involves?

Addition of hydrogen Signup and view all the answers

Which of the following does not involve a chemical reaction?

Melting of candle wax on heating Signup and view all the answers

Which acid is present in tomato?

Citric Acid Signup and view all the answers

Which of the following is a strong acid?

HCl pH 1 Signup and view all the answers

Na2CO3.10H2O is known as?

Washing soda Signup and view all the answers

PH value less than 7 indicates that the solution is?

Acidic Signup and view all the answers

Which of the following is neutral salt?

CH3COONH4 Signup and view all the answers

Lactic acid is present in?

Curd Signup and view all the answers

Farmers neutralize the effect of acidity on the soil by adding?

Slaked lime Signup and view all the answers

Which of the following are present in a dilute aqueous solution of hydrochloric acid?

H3O + Cl– Signup and view all the answers

CuSO4.5H2O: In this compound, the water molecule is called?

Water of crystallization Signup and view all the answers

Which of the following salts does not contain water of crystallization?

Baking soda Signup and view all the answers

An aqueous solution turns the red litmus solution blue. Excess addition of which of the following solutions would reverse the change?

Hydrochloric acid Signup and view all the answers

In which pH range does our body work to survive in the atmosphere?

7.0 to 7.8 Signup and view all the answers

What is the chemical formula of POP (Plaster of Paris)?

CaSO4.1/2H2O Signup and view all the answers

What happens when a solution of an acid is mixed with a solution of a base in a test tube?

Salt formation takes place Signup and view all the answers

Which salt is acidic in nature?

NH4Cl Signup and view all the answers

When a base reacts with a metal, it forms a salt, and hydrogen gas is released. By what method can the presence of hydrogen be detected?

By a burning candle Signup and view all the answers

At what temperature is gypsum heated to form Plaster of Paris?

100°C Signup and view all the answers

Sodium carbonate reacts with hydrochloric acid and produces?

All of the above Signup and view all the answers

Which acid is present in tamarind?

Tartaric acid Signup and view all the answers

Which of the following oxides of iron would be obtained on the prolonged reaction of iron with steam?

Fe3O4 Signup and view all the answers

A non-metal used to preserve food material is?

Nitrogen Signup and view all the answers

The arrangement for copper, tin, lead, and mercury, according to the reactivity series, is?

Tin > Lead > Copper > Mercury Signup and view all the answers

The metals that float when treated with water are?

Sodium and calcium Signup and view all the answers

Aluminum is used for making cooking utensils. Which of the following properties of aluminum are responsible for the same?

(iv) High melting point Signup and view all the answers

When hydrochloric acid is added to barium hydroxide, a white-colored compound is formed. Which of the following option gives the complete chemical reaction?

2HCl + Ba(OH)2 → BaCl2 + 2HOH Signup and view all the answers

What happens when a pellet of sodium is dropped in water?

It catches fire and forms hydroxide Signup and view all the answers

The chemical reaction between a piece of copper and nitric acid is given by the chemical equations, Cu + HNO3 → Cu(NO3)2 + H2; H2 + HNO3 → H2O + NO2. What can be inferred from the chemical equation?

Hydrogen gas gets oxidized by HNO3 to form water Signup and view all the answers

Which of the following options gives the process of extraction of mercury from its ore cinnabar?

Cinnabar to convert it into mercuric oxide and then heating it again Signup and view all the answers

When calcium oxide is added to water, it completely dissolves in water without forming bubbles. What products are formed in this reaction?

Ca(OH)2 Signup and view all the answers

A student studying the chemical properties of metals finds incomplete chemical reactions in his book, as shown below: MgO + HNO3 → Which option completes the reaction?

MgO + HNO3 → Mg(NO3)2 + H2O Signup and view all the answers

Which of the following can undergo a chemical reaction?

CuSO4 + Fe Signup and view all the answers

Pick the statement which is correct about the non-metal.

All of these Signup and view all the answers

When a non-metal is allowed to react with water:

No products are formed Signup and view all the answers

Study Notes

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General Science Questions

Magnesium Ribbon: Rubbed before burning to remove basic magnesium carbonate coating.
Sodium Chloride Formation: Reactants are sodium and chlorine; product is sodium chloride (table salt).
Aluminium Chloride Reaction: The balanced chemical equation is 2Al + 3Cl2 → 2AlCl3.
Water Composition: Hydrogen and oxygen in water are present in a 2:1 ratio by volume.
Barium Hydroxide and Hydrochloric Acid: Reaction yields BaCl2 + 2H2O; balanced by 2HCl + Ba(OH)2 → BaCl2 + 2HOH.
Chemical Reactions: Melting candle wax does not involve a chemical change, while burning does.
Chemical Formula Identifications: Magnesium oxide is MgO; carbon disulphide formation absorbs heat.

Acids and Bases

Acidity in Solutions: pH below 7 indicates an acidic solution; strong acid example: HCl with pH 1.
Neutral Salts: Example includes CH3COONH4, while NH4Cl is acidic.
Soil Neutralization for Farmers: Achieved by adding slaked lime (calcium hydroxide).
Water of Crystallisation: Present in CuSO4.5H2O; non-example is baking soda, which lacks water of crystallisation.

Chemical Properties and Reactions

Hydrolysis Reaction of Calcium Oxide: Forms Ca(OH)2 when mixed with water.
Extraction of Mercury: Conducted by heating cinnabar to convert it into mercuric oxide.
Sodium in Water: Reacts vigorously to form sodium hydroxide and hydrogen gas, which combusts.
Copper Reaction with Nitric Acid: Causes oxidation of HNO3 to form NO2; produces water.

Reactivity and Group Properties

Reactivity Series Order: Tin > Lead > Copper > Mercury indicates relative metallic reactivity.
Non-metal Characteristics: Most non-metal oxides tend to be acidic, and chlorine reacts with hydrocarbons in the presence of sunlight to yield chlorinated products.

Basic Chemistry Concepts

Oxidation and Reduction: Oxidation involves the addition of oxygen, while reduction involves the addition of hydrogen.
Endothermic vs. Exothermic Reactions: C + 2S → CS2 is an endothermic reaction (absorbs heat); reactions releasing heat are exothermic.
Importance of pH: Human body functions optimally at pH 7.0 to 7.8.

Practical Applications in Chemistry

Detection of Hydrogen: The presence of hydrogen can be confirmed with a burning candle.
Thermal Decomposition: Magnesium oxide reacts with HNO3 as part of a thermal decomposition reaction.

Summary of Chemical Groups

Carbon Compounds: Ethane (C2H6) signifies the presence of two carbon atoms; functional groups can be identified in carbon compounds.
Determining Reactivity: Displacement and double displacement reactions highlight the behaviors of metals and nonmetals in reactions with acids and bases.

Conclusion

Comprehensive understanding of chemical reactions, pH levels, and properties of elements and compounds is essential for mastering concepts within the general science curriculum, especially for entrance examinations.### Chemical Reactions and Compounds
Hydrogen addition to compounds often occurs during hydrogenation.
Oxygen addition typically involves oxidation reactions.
Substitution reactions involve replacing a hydrogen atom with another atom or group.
Breaking double and triple bonds into single bonds is characteristic of certain reaction mechanisms.

Properties of Ethanoic Acid

Pure ethanoic acid has a low melting point; it can freeze in winter, indicating this property.

Molecular Formulas

Cyclobutane has a molecular formula of C4H8.

Soap Molecules

Soap molecules have dual properties with an ionic end and a carbonic chain; the carbonic chain interacts with oil.

Homologous Series

Methane, ethane, and propane form a homologous series differing by a CH2 group.
C3H4 belongs to the homologous series of alkynes.

Chemical Bonding

Ethene consists of 2 carbon atoms and 4 hydrogen atoms, with carbon atoms sharing electrons to form covalent bonds.
Ionic compounds exhibit high melting and boiling points and conduct electricity in solutions or molten states.

Fullerenes

C60 is the most stable fullerene and resembles a soccer ball, containing fused six-membered carbon rings.

Hydrocarbons and Isomerism

Methane has four single bonds.
A minimum of four carbon atoms is required for a hydrocarbon to exhibit isomerism.

Periodic Table Trends

The modern periodic table is based on atomic number, not atomic mass.
Fluorine is the most reactive element in group 17.
Atomic radii decrease from sodium to argon in the third period.
Elements in the same group have similar properties; X with formula XCl2 likely belongs to group 2.

Electropositive Character and Groups

Electropositive character decreases across a period from left to right.
Group 18 elements are known as noble gases.
Transition metals are found in groups 3 to 12.

Boron and Electronegativity

Boron, a non-metal in group 13, can share three electrons.
Electronegativity increases as more electrons are added to the same shell across periods.

Human Digestive System

Food digestion begins in the mouth due to saliva.
The correct sequence of the alimentary canal: Mouth → oesophagus → stomach → small intestine → large intestine.

Respiration and Plant Processes

Anaerobic respiration in plants produces ethanol, carbon dioxide, and energy.
Stomatal pore opening and closing depend on water in guard cells.

Reproductive Biology

Fruits develop from the ovary of a flower; reproduction ensures species continuation.
The male reproductive parts of flowers are called androecium.
IUCD is utilized for contraception.

Hormones and Body Responses

Hormonal imbalances can lead to menstrual cycle irregularities, often requiring oestrogen treatment.
Blood pressure is regulated by the medulla, pons, and cerebellum.

Transmission of Information

Communication within neurons follows the pathway: Dendrite → cell body → axon → nerve ending.
Electrical signals transmit information across plant cells in response to stimuli.

Diseases and Medical Conditions

AIDS is caused by a virus, and syphilis is transmitted sexually.
Emphysema involves the destruction of the alveolar wall and is linked to tobacco smoke.

Conditions Impacting Survival

Thermophilic archaebacteria in hot springs have a resilient cell wall which aids in survival during temperature changes.### Cell Division and Genetics
Cysts can divide multiple times, resulting in numerous daughter cells.
A human zygote has a chromosome ratio of 2:1 compared to a human sperm.
Spores of Rhizopus develop into new individuals through division and growth.
After puberty, females begin the production of eggs in their ovaries.
The sperm's path after being released from the male reproductive system is: testis → vas deferens → urethra → penis.

Mendelian Genetics

Mendel used Pisum Sativum (pea plants) for his breeding experiments.
A gene is a DNA segment that provides information for producing a single protein.
Genetic variation can be observed in traits, such as different eye colors between siblings.

Inheritance and Ratios

Crossing pure tall (TT) and pure short (tt) pea plants yields an F2 generation with a 3:1 ratio of tall to short plants.
A male offspring inherits a combination of X and Y chromosomes from its parents.
In a cross between two pea plants with different traits, new combinations can arise in the F2 generation, such as round yellow seeds and wrinkled green seeds.

Origin of Life and Evolution

Miller and Urey's experiment aimed to demonstrate the origin of life using gases like methane, ammonia, hydrogen, and water vapor.
Analogous organs include the wings of a pigeon and a bat, displaying similarity in function but differences in structure.
Concepts of natural selection, struggle for existence, and survival of the fittest are central to Darwin's theory of evolution.

Light and Optics

When a plane mirror is rotated, the reflected ray turns through twice the angle of rotation, while the size of the image remains unchanged.
The total number of images formed between two plane mirrors depends on the angle of inclination.
The focal length of a plane mirror is infinite; images formed by convex mirrors are always virtual.

Eye and Vision

The crystalline lens of the eye performs most of the refraction for incoming light.
The retina is where the image of an object is formed in the eye.
Red light is less scattered in the atmosphere, making it more visible in foggy conditions.

Rainbow Formation and Light Phenomena

A rainbow is created through refraction, dispersion, and total internal reflection of light.
Stars appear to twinkle due to light variances through the Earth's atmosphere.
The splitting of white light into colors when passing through a prism is due to different wavelengths having varying refractive indices.

Color Perception and Atmospheric Effects

At sunrise and sunset, the sun appears red because red light has a longer wavelength and travels a greater distance through the atmosphere.
At noon, the sun appears white due to minimal scattering of light.

Miscellaneous

Genetic traits can be acquired but not inherited; for example, body size can change without being passed to offspring.
Light behaves differently in various mediums, resulting in changes in speed and color visibility.

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