100 Most Probable Questions PDF

## Note: Questions in this section are selected based on repetitive themes and concepts from past examinations, though patterns and typologies may vary. ### 1. Chemical Reactions and Equations 1. MnO₂ + xHCl → MnCl₂ + H₂O + zCl₂ In order to balance the above chemical equation, the values of x, y a...

## Note: Questions in this section are selected based on repetitive themes and concepts from past examinations, though patterns and typologies may vary. ### 1. Chemical Reactions and Equations 1. MnO₂ + xHCl → MnCl₂ + H₂O + zCl₂ In order to balance the above chemical equation, the values of x, y and z respectively are: (1 M) (2024, 2023) (a) 6,2,2 (b) 4, 1, 2 (c) 4, 2, 1 (d) 2, 2, 1 2. Which of the following statements about the reaction given below are correct? MnO₂ + 4HCl → MnCl₂ + 2H₂O + Cl₂ (i) HCl is oxidized to Cl₂ (ii) MnO₂ is reduced to MnCl₂ (iii) MnCl₂ acts as an oxidizing agent (iv) HCl acts as an oxidizing agent (a) (ii), (iii) and (iv) (1 M) (2024, 2023, 2022, 2016) (b) (i), (ii) and (iii) (c) (i) and (ii) only (d) (iii) and (iv) only 3. The emission of brown fumes in the given experimental set-up is due to: (1 M) (2024, 2023, 2022) - A diagram of a test tube with a burner below it and brown fumes coming out the top is shown. - The label "Lead nitrate" is attached to the tube. (a) thermal decomposition of lead nitrate which produces brown fumes of nitrogen dioxide. (b) thermal decomposition of lead nitrate which produces brown fumes of lead oxide. (c) oxidation of lead nitrate forming lead oxide and nitrogen dioxide. (d) oxidation of lead nitrate forming lead oxide and oxygen. 4. Assertion (A): Reaction of Quicklime with water is an exothermic reaction. Reason (R): Quicklime reacts vigorously with water releasing a large amount of heat. (1 M) (2024, 2023, 2020) 5. While studying the double displacement reaction, the solutions of barium chloride and sodium sulphate are mixed together. (i) What do you observe as soon as the two solutions are mixed together? (ii) What will happen in the above observation made by you after ten minutes? (2 M) (2022, 2020, 2019, 2016) 6. (i) While electrolysing water before passing the current some drops of an acid are added. Why? Name the gases liberated at cathode and anode. Write the relationship between the volume of gas collected at anode and the volume of gas collected at cathode. (ii) What is observed when silver chloride is exposed to sunlight? Give the type of reaction involved. (3 M) (2024, 2023) 7. Decomposition reactions require energy either in the form of heat or light or electricity for breaking down the reactants. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light and electricity. (3 M) (2024, 2020, 2019, 2018) 8. Select (i) combination reaction, (ii) decomposition reaction and (iii) displacement reaction from the following chemical equations: (3 M) (2023, 2022, 2019, 2015) (i) ZnCO₃(s) → ZnO(s) + CO₂(g) (ii) Pb(s) + CuCl₂(aq) → PbCl₂(aq) + Cu(s) (iii) NaBr(aq) + AgNO₃(aq) → AgBr(s) + NaNO₃(aq) (iv) H₂(g) + Cl₂(g) → 2HCl(g) (v) Fe₂O₃ + 2A1 → Al₂O₃ + 2Fe (vi) 3H₂(g) + N₂(g) → 2NH₃(g) Heat (vii) CaCO₃(s) → CaO(s) + CO₂(g) ### 2. Acids, Bases and Salts 9. The table below has information regarding pH and the nature (acidic/basic) of four different solutions. Which one of the options in the table is correct? (1M) (2023, 2019) | Option | Solution | Colour of pH paper | Approximate pH value | Nature of solution | |---|---|---|---|---| | (a) | Lemon juice | Orange | 3 | Basic | | (b) | Milk of magnesia | Blue | 10 | Basic | | (c) | Gastric juice | Red | 6 | Acidic | | (d) | Pure water | Yellow | 7 | Neutral | 10. In the experimental set-up given below, it is observed that on passing the gas produced in the reaction in the solution 'X' the solution 'X' first turns milky and then colourless. (1 M) (2023, 2022, 2019) - A diagram is shown with a beaker of dilute hydrochloric acid connected to a beaker of sodium carbonate solution. - The symbol "X" is placed between the two beakers, indicating the gas produced by the reaction passes into the beaker labelled "X". The option that justifies the above stated observation is that 'X' is aqueous calcium hydroxide and (a) it turns milky due to carbon dioxide gas liberated in the reaction and after sometime it becomes colourless due to formation of calcium carbonate. (b) it turns milky due to formation of calcium carbonate and on passing excess of carbon dioxide it becomes colourless due to formation of calcium hydrogen carbonate which is soluble in water. (c) it turns milky due to passing of carbon dioxide through it. It turns colourless as on further passing carbon dioxide, sodium hydrogen carbonate is formed which is soluble in water. (d) the carbon dioxide liberated during the reaction turns lime water milky due to formation of calcium hydrogen carbonate and after some time it turns colourless due to formation of calcium carbonate which is soluble in water. 11. (a) (i) A compound 'X' which is prepared from gypsum has the property of hardening when mixed with proper quantity of water. Identify 'X' and write its chemical formula. (ii) State the difference in chemical composition between baking soda and baking powder: (2 M) (2023, 2022, 2020, 2018) 12. During electrolysis of brine, a gas 'G' is liberated at anode. When this gas 'G' is passed through slaked lime, a compound 'C' is formed, which is used for disinfecting drinking water. (i) Write formula of 'G' and 'C'. (ii) State the chemical equation involved. (iii) What is common name of compound 'C'? Give its chemical name. (3 M) (2023, 2020, 2019, 2016) 13. (i) Suggest a safe procedure of diluting a strong concentrated acid. (ii) Name the salt formed when sulphuric acid is added to sodium hydroxide and write its pH.. (iii) Dry HCl gas does not change the colour of dry blue litmus paper. Why? (3 M) (2023, 2019, 2015) 14. How is washing soda prepared from sodium carbonate? Give its chemical equation. State the type of this salt. Name the type of hardness of water which can be removed by it? (3 M) (2023, 2020) 15. Write the chemical composition of tooth enamel. Under what conditions of pH it starts corroding? Explain the reason of tooth decay and suggest one method to prevent it. (3 M) (2024, 2023) 16. Salts play a very important role in our daily life. Sodium chloride which is known as common salt is used almost in every kitchen. Baking soda is also a salt used in faster cooking as well as in baking industry. The family of salts is classified on the basis of cations and anions present in them. (2024, 2023, 2022, 2019) (a) Identify the acid and base from which Sodium chloride is formed. (b) Find the cation and the anion present in Calcium sulphate. (c) "Sodium chloride and washing soda both belong to the same family of salts." Justify this statement. (1 M) OR (c) Define the term pH scale. Name the salt obtained by the reaction of Potassium hydroxide and Sulphuric acid and give the pH value of its aqueous solution. (2 M) ### 3. Metals and Non-metals 17. The oxide which can react with HCl as well as KOH to give corresponding salt and water is (a) CuO (1 M) (2024, 2022, 2019) (b) Al₂O₃ (c) Na₂O (d) K₂O 18. Mrignayani was doing the experiment of comparing reactivity of metals in the laboratory. She was given aluminium metal and was told to check reactivity by using four solutions as shown below. She would observe that reaction takes place in: (IM) (2024, 2022, 2019, 2015) (A) Al₂(SO₄)₃ (B) FeSO₄ Al Al (C) ZnSO₄ (D) CuSO₄ Al Al (a) A and B (b) B, C and D (c) A, C and D (d) C and D 19. A metal and a non-metal that exists in liquid state at the room temperature are respectively: (1 M) (2024, 2023, 2016) (a) Bromine and Mercury (b) Mercury and Iodine (c) Mercury and Bromine (d) Iodine and Mercury 20. Silver articles become black when kept in open for some time, whereas copper vessels lose their shiny brown surfaces and gain a green coat when kept in open. Name the substances present in air with which these metals react and write the name of the products formed. (2 M) (2019, 2016, 2015) 21. Carbon cannot reduce the oxides of sodium, magnesium and aluminum to their respective metals. Why? Where are these metals placed in the reactivity series? How are these metals obtained from their ores? Take an example to explain the process of extraction along with chemical equations. (5M) (2020, 2018) 22. The metals produced by various reduction processes are not very pure. They contain impurities, which must be removed to obtain pure metals. The most widely used method for refining impure metals is electrolytic refining. (2024, 2018) (i) What is the cathode and anode made of in the refining of copper by this process? (ii) Name the solution used in the above process and write its formula. (1 M) (iii) (A) How copper gets refined when electric current is passed in the electrolytic cell? Or (iii) (B) You have two beakers 'A' and 'B' containing copper sulphate solution. What would you observe after about 2 hours if you dip a strip of zinc in beaker 'A' and a strip of silver in beaker 'B '? Give reason for your observations in each case. (2 M) 23. Almost all metals combine with oxygen to form metal oxides. Metal oxides are generally basic as nature. But some metal oxides show both basic as well as acidic behaviour. Different metals show different reactivities towards oxygen. Some react vigorously while some do not react at all. (2023, 2022, 2020, 2019) (a) What happens when copper is heated in air? (Give the equation of the reaction involved). (1 M) (b) Why are some metal oxides categorized as amphoteric? Give one example. (1 M) (c) Complete the following equations: (i) Na₂O(s) + H₂O→ (ii) Al₂O₃ + 2NaOH → Or (c) On burning Sulphur in oxygen a colourless gas is produced. (i) Write chemical equation for the reaction. (ii) Name the gas formed. (iii) State the nature of the gas. (iv) What will be the action of this on a dry litmus paper? (2 M) 24. The melting points and boiling points of some ionic compounds are given below: (2023, 2022, 2020) | Compound | Melting Point (K) | Boiling Point (K) | |---|---|---| | NaCl | 1074 | 1686 | | LiCl | 887 | 1600 | | CaCl₂ | 1045 | 1900 | | CaO | 2850 | 3120 | | MgCl₂ | 981 | 1685 | These compounds are termed ionic because they are formed by the transfer of electrons from a metal to a non-metal. The electron transfer in such compounds is controlled by the electronic configuration of the elements involved. Every element tends to attain a completely filled valence shell of its nearest noble gas or a stable octet. (i) Show the electron transfer in the formation of magnesium chloride. (1 M) (ii) List two properties of ionic compounds other than their high melting and boiling points. (1 M) (iii) (A) While forming an ionic compound, say sodium chloride, how does sodium atom attain its stable configuration? Or (B) Give reasons: (i) Why do ionic compounds in the solid state not conduct electricity? (ii) What happens at the cathode when electricity is passed through an aqueous solution of sodium chloride? (2 M) ### 4. Carbon and its Compounds 25. A student took four test tubes P, Q, R and S and filled about 8 mL of distilled water in each. After that he dissolved an equal amount of Na₂SO₄ in P, K₂SO₄ in Q, CaSO₄ in R and MgSO, in S. On adding an equal amount of soap solution and shaking each test tube well, a good amount of lather will be obtained in the test tubes: (a) P and Q (c) P, Q and S (1 M) (2019, 2017, 2016, 2015) (b) P and R (d) Q, R and S 26. A gas is liberated immediately with a brisk effervescence, when you add acetic acid to sodium hydrogen carbonate powder in a test tube. Name the gas and describe the test that confirms the identity of the gas. (2 M) (2019, 2017, 2016, 2015) 27. (a) Why are most carbon compounds poor conductors of electricity? (b) Write the name and structure of a saturated compound in which the carbon atoms are arranged in a ring. Give the number of single bonds present in this compound. (3 M) (2024, 2019, 2018) 28. (a) Draw the electron dot structure for ethyne. (b) List two differences between the properties exhibited by covalent compounds and ionic compounds. (3 M) (2023, 2022, 2019, 2015) 29. Distinguish between esterification and saponification reactions with the help of the chemical equations for each. State one use of each (i) esters, and (ii) saponification process. (3 M) (2023, 2017, 2016) 30. (a) A saturated organic compound 'A' belongs to the homologous series of alcohols. On heating 'A' with concentrated sulphuric acid at 443 K. it forms an unsaturated compound B' with molecular mass 28u. The compound B on addition of one mole of hydrogen in the presence of Nickel, changes to a saturated hydrocarbon 'C'. (i) Identify A, B and C. (ii) Write the chemical equations showing the conversion of A into B. (iii) What happens when compound C undergoes combustion? (iv) State one industrial application of hydrogenation reaction. (v) Name the products formed when compound A reacts with sodium. (5 M) (2023, 2020, 2019, 2018, 2016) 31. (a) (i) Give reason why carbon can neither form C⁴⁺ cations nor C⁻¹ anions but form covalent compounds. (ii) What is homologous series of carbon compound? Write the molecular formula of any two consecutive members of homologous series of aldehydes.. (iii) Draw the structure of the molecule of cyclohexane (CH₂)₆. (5 M) (2024, 2022, 2020) 32. (i) Draw the structure of the following compounds: (a) Butanoic acid (b) Chloropentane (ii) How are structure (i) and structure (ii) given below related to one another? Give reason to justify your answer. CH₃-CH₂-CH²-CH²-CH₃ CH₃-CH₂-C-CH₂-CH₃ Structure (i) Structure (ii) Draw one more possible structure for above case. (iii) Differentiate between saturated and unsaturated carbon compounds on the basis of their general formula. (5M) (2023, 2016 ### 5. Life Processes 34. Opening and closing of stomata is due to: (1 M) (2024, 2023, 2022, 2020) (a) High pressure of gases inside the cells. (b) Movement of water in and out of the guard cells. (c) Stimulus of light in the guard cells. (d) Diffusion of CO₂ in and out of the guard cells. 35. (a) State the role played by the following in the process of digestion. (i) Enzyme trypsin (ii) Enzyme lipase (b) List two functions of finger-like projections present in the small intestine. (3 M) (2024, 2020) 36. (i) Why is respiratory pigment needed in multicellular organisms with large body size? (ii) Give reasons for the following: (a) Rings of cartilage are present in the throat. (b) Lungs always contain a residual volume of air. (c) The diaphragm flattens and ribs are lifted up when we breathe in. (d) Walls of alveoli contain an extensive network of blood vessels. (1 M) (2 M) (2024) 37. Mention the pathway of urine starting from the organ of its formation. Name four substances which are re-absorbed from the initial filtrate in the tubular part of the nephron. (3 M) (2016) 38. (i) What is double circulation? (ii) "Why is the separation of the right side and the left side of the heart useful? How does it help birds and mammals? (3 M) (2023) 39. (a) Define excretion. (b) Name the basic filtration unit present in the kidney. (c) Draw excretory system in human beings and label the following organs of excretory system which perform following functions: (i) form urine. (ii) is a long tube which collects urine from kidney.. (iii), store urine until it is passed out. (5M) (2018) 40. (a) Why is there a difference in the rate of breathing between aquatic organisms and terrestrial organisms? Explain. (b) Draw a diagram of human respiratory system and label-pharynx, trachea, lungs, diaphragm and alveolar sac on it.. (5M) (2020, 2015, 2014). 41. (a) Write the correct sequence of steps followed during journey of oxygen rich blood from lungs to various organs of human body. (b) What happens when the system of blood vessels develop a leak? (5M) (2020) 42. (a) Mention any two components of blood. (b) Trace the movement of oxygenated blood in the body. (c) Write the function of valves present in between atria and ventricles. (d) Write one structural difference between the composition of artery and veins. (5M) (2018, 2016) 43. (a) Draw a diagram of human alimentary canal and label gall bladder, pancreas, liver and small intestine in it. (b) Give two reasons to explain why absorption of digested food occurs mainly in the small intestine. (5 M) (2020) 44. (i) Name the process and explain the type of nutrition found in green plants. List the raw materials required for this process. Give chemical equation for the mentioned process. (ii) Write three events that occur during this process. (5M) (2018) ### 6. Control and Coordination 45. Name the part of brain which is responsible for the following actions: (i) Maintaining posture and balance (ii) Beating of heart (iii) Thinking (iv) Blood pressure (2 M) (2023, 2015) 46. Define reflex action. With the help of a flow chart show the path of a reflex action such as sneezing. (3 M) (2024, 2023, 2019, 2015) 47. A squirrel is in a scary situation. Its body has to prepare for either fighting or running away. State the immediate changes that take place in its body so that the squirrel is able to either fight or run? (3 M) (2020) 48. Why is chemical communication better than electrical impulses as a means of communication between cells in a multi-cellular organism? (3 M) (2020) 49. Draw a diagram showing the correct positions of pancreas, thyroid gland, pituitary gland and adrenal gland in human being. (3 M) (2016) 50. What are plant hormones? Name the plant hormones responsible for the following: (i) Growth of stem (ii) Promotion of cell division (iii) Inhibition of growth (iv) Elongation of cells (3 M) (2019, 2016) 51. (a) Draw the structure of a neuron and label the following on it: (i) Dendrite (ii) Cell body (iii) Nucleus (iv) Axon (b) Name the parts of a neuron: (i) Where information is acquired.. (ii) Through which information travels as an electrical impulse. (iii) Where this impulse must be converted into a chemical signal for onward transmission. (c) Define neuromuscular junction. (5M) (2016) 52. (a) Why is the use of iodised salt advisable? Name the disease caused due to deficiency of iodine in our diet and state its one symptom. (b) How do nerve impulses travel in the body? Explain. (5 M) (2019) ### 7. How do Organisms Reproduce? 53. Mention the functions of (a) Placenta (b) Fallopian tubes (c) Uterus and (d) Ovary in the human female reproductive system. (2 M) (2022) 54. (a) Differentiate between binary fission in Amoeba and binary fission in Leishmania. (b) How does reproduction take place in malarial parasite? (2 M) (2022) 55. What are the functions of testis in the human male reproductive system? Why are these located outside the abdominal cavity? Who is responsible for bringing about changes in appearance seen in boys at the time of puberty? (3 M) (2016) 56. Define the term pollination. Differentiate between self pollination and cross pollination. What is the significance of pollination? (3 M) (2020, 2019) 57. (i) Name and explain the two modes of asexual reproduction observed in hydra. (ii) What is vegetative propagation? List two advantages of using this technique. (5 M) (2024, 2023, 2022 58. (A) (ⅰ) Name three techniques/devices used by human females to avoid pregnancy. Mention the side effects caused by each. (ii) What will happen if in a human female (a) fertilisation takes place, (b) an egg is not fertilised? (5 M) (2024, 2023, 2017) 59. (a) Draw a diagram to show spore formation in Rhizopus. (b) With the help of an example differentiate between the process of Budding and Fragmentation. (c) Why is vegetative propagation practiced for growing some type's of plants? (5 M) (2020) 60. (a) Draw a diagram showing germination of pollen on stigma of a flower and mark on it the following organs/parts: (i) Pollen Grain (ii) Pollen tube (iii) Stigma (iv) Female germ cell (b) State the significance of pollen tube. (c) Name the parts of flower that develop after fertilisation into (i) Seed (ii) Fruit (5M) (2022, 2020, 2015) ### 8. Heredity 61. Sex of an individual is determined by different factors in various species. Some animals rely entirely on the environmental cues, while in some other animals the individuals can change their sex during their lifetime indicating that sex of some species is not genetically determined. However, in human beings, the sex of an individual is largely determined genetically. (4 M) (2022) (a) In what way are the sex chromosomes ‘X' and 'Y' different in size? Name the mismatched pair of sex chromosomes in humans. (b) Write the number of pair/pairs of sex chromosomes present in human beings. In which one of the parent (male / female) perfect pair/pairs of sex chromosomes are present? (c) Citing two examples, justify the statement "Sex of an individual is not always determined genetically". Or Draw a flow chart to show that sex is determined genetically in human beings. 62. The most obvious outcome of the reproductive process is the generation of individuals of similar design, but in sexual reproduction they may not be exactly alike. The resemblances as well as differences are marked. The rules of heredity determine the process by which traits and characteristics are reliably inherited. Many experiments have been done to study the rules of inheritance. (2023) (i) Why an offspring of human being is not a true copy of his parents in sexual reproduction? (1 M) (ii) While performing experiments on inheritance in plants, what is the difference between F₁ and F₂ generation? (1 M) (iii) (A) Why do we say that variations are useful for the survival of a species over time? Or (iii) (B) Study Mendel's cross between two plants with a pair of contrasting characters. RRYY × rryy Round Yellow Wrinkled Green He observed 4 types of combinations in F₂ generation. Which of these were new combinations? Why do new features which are not present in the parents, appear in F₂ generation? (2 M) 63. In order to trace the inheritance of traits Mendel crossed pea plants having one contrasting character or a pair of contrasting characters. When he crossed pea plants having round and yellow seeds with pea plants having wrinkled and green seeds, he observed that no plants with wrinkled and green seeds were obtained in the F₁ generation. When the F₁ generation pea plants were cross-bred by self-pollination, the F₂ generation had seeds with different combinations of shape and colour also. (2023) (a) Write any two pairs of contrasting characteristics of pea plant used by Mendel other than those mentioned above. (1 M) (b) Differentiate between dominant and recessive traits. (1 M) (c) State the ratio of the combinations observed in the seeds of F₂ generation (in the above case). What do you interpret from this result? Or (c) Given below is a cross between a pure violet flowered pea plant (V) and a pure white flowered pea plant (v). Diagrammatically explain what type of progeny is obtained in F₁ generation and F₂ generation: Pure violet flowered plant × Pure white flowered plant. (VV) (2 M) ### 9. Light-Reflection and Refraction 64. The correct sequencing of angle of incidence, angle of emergence, angle of refraction and lateral displacement shown in the following diagram by digits 1, 2, 3 and 4 is: (1 M) (2017) - a diagram is shown with angled lines representing light passing through two different mediums. (a) 2, 4, 1, 3 (c) 1, 2, 4, 3 (b) 2, 1, 4, 3 (d) 2, 1, 3, 4 65. A student used a device (X) to obtain/focus the image of a well illuminated distant building on a screen (S) as shown below in the diagram. Select the correct statement about the device (X). (1 M) (2015) - A diagram is shown of light passing through a device, labelled "X", aimed toward a screen labelled "S". (a) The device is a concave lens of focal length 8 cm. (b) This device is a convex mirror of focal length 8 cm. (c) This device is a convex lens of focal length 4 cm. (d) This device is a convex lens of focal length 8 cm 66. A ray of light is incident as shown. If A, B and C are three different transparent media, then which among the following options is true for the given diagram? (1 M) (2022) - a diagram is shown of light passing through three different mediums, labelled A, B and C, with angles 1, 2, 3 and 4 labelled. (a) ∠1 > ∠2 (b) ∠1 <∠2 (c) ∠3 = ∠2 (d) ∠3 > ∠4 67. Assertion (A): The rainbow is a natural spectrum of sunlight in the sky. Reason (R): Rainbow is formed in the sky when the sun is overhead and water droplets are also present in air. (1 M) (2024) 68. The absolute refractive indices of glass and water are 4/3 and 3/2 respectively. If the speed of light in glass is 2 × 10⁸ m/s, calculate the speed of light in (i) vacuum, (ii) water. (2 M) (2023, 2015) 69. (a) A security mirror used in a big showroom has radius of curvature 5 m. If a customer is standing at a distance of 20 m from the cash counter, find the position, nature and size of the image formed in the security mirror. (b) Neha visited a dentist in his clinic. She observed that the dentist was holding an instrument fitted with a mirror. State the nature of this mirror and reason for its use in the instrument used by dentist. (5 M) (2020) 70. Draw a ray diagram in each of the following cases to show the formation of image, when the object is placed: (i) between optical centre and principal focus of a convex lens. (ii) anywhere in front of a concave lens. (iii) at 2F of a convex lens. State the signs and values of magnifications in the above mentioned cases (i) and (ii). (5 M) (2020) 71. Analyse the following observation table showing variation of image distance (v) with object distance (u) in case of a convex lens and answer the questions that follow, without doing any calculations: (5M) (2017) | S. No.| Object distance u (cm) | Image distance v (cm) | |---|---|---| | 1 | -90 | +18 | | 2 | -60 | +20 | | 3 | -30 | +30 | | 4 | -20 | +60 | | 5 | -18 | +90 | | 6 | -10 | +100 | (a) What is the focal length of the convex lens? Give reason in support of your answer. (b) Write the serial number of that observation which is not correct. How did you arrive at this conclusion? (c) Take an appropriate scale to draw ray diagram for the observation at S. No. 4 and find the approximate value of magnification. 72. "A convex lens can form a magnified erect as well as magnified inverted image of an object placed in front of it." Draw ray diagram to justify this statement stating the position of the object with respect to the lens in each case. An object of height 4 cm is placed at a distance of 20 cm from a concave lens of focal length 10 cm. Use lens formula to determine the position of the image formed. (5 M) (2015, 2022, 2016) 73. The ability of a medium to refract light is expressed in terms of its optical density. Optical density has a definite connotation. It is not the same as mass density. On comparing two media, the one with the large refractive index is optically denser medium than the other. The other medium with a lower refractive index is optically rarer. Also the speed of light through a given medium is inversely proportional to its optical density. (2023) (i) Determine the speed of light in diamond if the refractive index of diamond with respect to vacuum is 2.42. Speed of light in vacuum is 3×10⁸ m/s. (1 M) (ii) Refractive indices of glass, water and carbon disulphide are 1.5, 1.33 and 1.62 respectively. If a ray of light is incident in these media at the same angle (say 0), then write the increasing order of the angle of refraction in these media. (1 M) (iii) (A) The speed of light in glass is 2×10⁸ m/s and in water is 2.25×10⁸ m/s. (2 M) (a) Which one of the two is optically denser and why? (b) A ray of light is incident normally at the water-glass interface when it enters a thick glass container filled with water. What will happen to the path of the ray after entering the glass? Give reason. Or (B) The absolute refractive indices of water and glass are 4/3 and 3/2 respectively. If the speed of light in glass is 2 × 10⁸ m/s, find the speed of light in (i) vacuum and (ii) water. 74. Study the data given below showing the focal length of three concave mirrors A, B and C and the respective distances of objects placed in front of the mirrors: (2024) | Case | Mirror | Focal Length (cm) | Object Distance (cm) | |---|---|---|---| | 1 | A | 20 | 45 | | 2 | B | 20 | 30 | | 3 | C | 15 | 20 | (i) In which one of the above cases the mirror will form a diminished image of the object? Justify your answer. (1 M) (ii) List two properties of the image formed