Chemistry Class 10 Quiz

The reaction of calcium oxide with water is an exothermic reaction, releasing heat.

The balanced equation for the combustion of propane is C3H8 + 5O2 → 3CO2 + 4H2O. This represents one molecule of propane reacting with five molecules of oxygen to generate three molecules of carbon dioxide and four molecules of water.

Iron is the most suitable material for the core of an electromagnet due to its strong ferromagnetic properties, meaning it readily attracts and concentrates magnetic fields.

In a neutralization reaction, an acid reacts with a base to form a salt and water. The salt is a compound formed from the positive ion of the base and the negative ion of the acid, while the water is formed from the hydrogen ions (H+) from the acid and the hydroxide ions (OH-) from the base.

A motor converts electrical energy into mechanical energy. It uses the interaction between magnetic fields and electric currents to create rotational motion.

The refractive index of a medium depends on the wavelength of light. Each substance has a unique refractive index, which describes how much the speed of light changes when it travels through that medium.

Medulla oblongata controls involuntary actions like heartbeat, breathing, and digestion.

According to the right-hand-thumb rule, if the thumb points in the direction of the current, the fingers curl in the direction of the magnetic field lines.

Fishes have only two chambers in their heart. Their heart has a single atrium and a single ventricle. This system is less efficient than the hearts of mammals and birds, which have four chambers.

The iris is the part of the eye that gives it color. It's a circular muscle responsible for controlling the amount of light entering the eye by adjusting the size of the pupil.

In a food chain, the flow of energy is unidirectional. Energy is transferred from one organism to another in a linear pathway, with some energy being lost at each transfer.

When an acid reacts with a metal, hydrogen gas is evolved. The acid provides hydrogen ions, which react with the metal to produce hydrogen gas and a salt.

The organs involved in reflex action are the spinal cord and motor neurons. A reflex arc starts with a sensory receptor, which sends a signal to the spinal cord. The spinal cord then quickly sends a signal to a motor neuron, causing a reaction without waiting for the brain to process the information.

Acids have a pH value less than 7. The pH scale measures the acidity or alkalinity of a solution. A pH of 7 is neutral, a pH lower than 7 is acidic, and a pH higher than 7 is basic or alkaline.

In a chemical reaction, the mass of the products is always equal to the mass of the reactants. This is known as the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction only rearranged.

Refraction of light occurs when light travels from one medium to another at a different speed. When light passes from one medium to another, its speed changes, causing it to bend. The amount of bending depends on the refractive indices of the two media.

Not all metals are ductile, Ductility is the ability of a solid material to deform under tensile stress without breaking. Gold, copper, and aluminum are examples of ductile metals.

The retina in the human eye contains both rod and cone cells for vision. Rod cells are responsible for vision in low light and can only detect changes in light intensity, while cone cells are responsible for color vision and can perceive different wavelengths of light.

A strong acid is an acid that fully ionizes in solution, meaning it completely dissociates into its ions. Examples of strong acids include hydrochloric acid (HCl), sulfuric acid (H2SO4), and nitric acid (HNO3).

Absorption of heat is an endothermic reaction where the system gains heat from its surroundings. As a result, the temperature of the system increases.

The cerebellum is the part of the brain that controls involuntary actions like balance, coordination, and movement. It receives information from the spinal cord and other parts of the brain and helps regulate muscle activity.

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of all living organisms. It's a double-stranded molecule that carries the genetic code in its sequence of nucleotides.

Gregor Mendel, through his experiments with pea plants, established the fundamental laws of genetics, which explain the inheritance of traits from parents to offspring.

“aq” indicates that the substance is dissolved in water. This notation means that the substance is in an aqueous solution, meaning it is dissolved in water.

Two metals with low melting points are mercury and gallium. Mercury is a liquid at room temperature, while gallium melts just above room temperature, making it useful for specialized applications where a low melting point is needed.

The direction of magnetic field lines outside a bar magnet is from north to south. The magnetic field lines emerge from the north pole of the magnet and enter the south pole. These lines form closed loops, meaning they never start or end.

The normal blood pressure of a healthy adult human is 120/80 mmHg. The first number, 120 mmHg, is the systolic pressure, which is the pressure of the blood in the arteries when the heart beats. The second number, 80 mmHg, is the diastolic pressure, which is the pressure of the blood in the arteries when the heart is at rest between beats.

The cerebrum is specialized for thinking, hearing, smelling, seeing, and other complex cognitive functions. It's the largest part of the human brain and is responsible for higher-order mental processes, sensory perception, and motor control.

A concave lens is used to correct myopia, which is nearsightedness. Myopia occurs when light focuses in front of the retina instead of on it, causing blurry vision for distant objects. Concave lenses diverge light rays before they enter the eye, correcting the focus.

The chemical formula of ethene is C2H4. Ethene is an unsaturated hydrocarbon with a double bond between the two carbon atoms. It's a colorless, flammable gas that is used as a starting material for the production of plastics and other chemicals.

The function of saliva is to moisten food, break down starches, and help with swallowing. Saliva contains enzymes, such as salivary amylase, which begins the digestion of starch, breaking it down into simpler sugars. It also lubricates food, allowing it to be easily moved through the digestive tract.