(a) The phenomenon is called dispersion of light. (b) White light is a mixture of seven colours. Each colour has a different wavelength and, hence, is refracted (bent) by the glass prism through different angles, resulting in a band of seven distinct colours. (c) To show recombination of spectrum ofRead more
(a) The phenomenon is called dispersion of light.
(b) White light is a mixture of seven colours. Each colour has a different wavelength and, hence, is refracted (bent) by the glass prism through different angles, resulting in a band of seven distinct colours.
(c) To show recombination of spectrum of white light, Newton used two prisms. The first prism disperses white light into seven colours. When this spectrum is passed through a second, inverted prism, it recombines the seven colours back into white light.
(a) Lime water turns milky because carbon dioxide gas reacts with calcium hydroxide solution to form calcium carbonate. Calcium carbonate is insoluble in water and appears as a white precipitate, giving the solution a milky appearance. This reaction is a common laboratory test for the presence of caRead more
(a) Lime water turns milky because carbon dioxide gas reacts with calcium hydroxide solution to form calcium carbonate. Calcium carbonate is insoluble in water and appears as a white precipitate, giving the solution a milky appearance. This reaction is a common laboratory test for the presence of carbon dioxide gas.
(b) When ethanoic acid reacts with sodium hydrogen carbonate, the products formed are sodium ethanoate (X), water, and carbon dioxide gas (Y). The reaction demonstrates the typical acid–carbonate reaction, producing effervescence due to carbon dioxide release. The sodium salt formed is soluble, while the gas evolved can turn lime water milky.
(c) Carbon dioxide released from the reaction is confirmed using lime water. It reacts with calcium hydroxide to form insoluble calcium carbonate, which makes the solution appear milky. The balanced reaction is:
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O. This simple test is widely used to detect carbon dioxide gas.
ANSWER: [A] Explanation: Correct option: (a) The near point of his eyes has receded away. The student can clearly see the blackboard but cannot read his textbook, which means he suffers from hypermetropia (farsightedness). In this defect, the near point of the eye shifts farther away than normal, maRead more
ANSWER: [A]
Explanation: Correct option: (a) The near point of his eyes has receded away. The student can clearly see the blackboard but cannot read his textbook, which means he suffers from hypermetropia (farsightedness). In this defect, the near point of the eye shifts farther away than normal, making nearby objects appear blurred.
ANSWER: [C] Explanation: Correct option: (c) 40 cm. To obtain an image of magnification M = − 1, the image must be real, inverted and of the same size as the object. This happens when the object is placed at twice the focal length of a convex lens. The given focal length is f = 20 cm. Hence, the objRead more
ANSWER: [C]
Explanation: Correct option: (c) 40 cm. To obtain an image of magnification M = − 1, the image must be real, inverted and of the same size as the object. This happens when the object is placed at twice the focal length of a convex lens. The given focal length is f = 20 cm. Hence, the object should be placed at 2f = 40 cm. At this position, the image is formed on the opposite side of the lens, also at 40 cm, with the same size as the object but inverted.
(i) Aluminium forms a thin protective oxide layer (Al₂O₃) on its surface when exposed to air. This layer prevents further corrosion, unlike iron which forms rust (Fe₂O₃·xH₂O) that flakes off. (ii) The dull appearance can be prevented by polishing or anodizing the aluminium surface to maintain its shRead more
(i) Aluminium forms a thin protective oxide layer (Al₂O₃) on its surface when exposed to air. This layer prevents further corrosion, unlike iron which forms rust (Fe₂O₃·xH₂O) that flakes off.
(ii) The dull appearance can be prevented by polishing or anodizing the aluminium surface to maintain its shine and protect it from corrosion.
(iii) Aluminium is lightweight, corrosion-resistant, and durable, making it ideal for roofing, whereas iron sheets are heavier and prone to rusting, requiring more maintenance.
A person allowed a narrow beam of white light from the sun to enter a dark room through a small aperture and placed a glass prism in its path in such a manner that the beam falls on the face AB of the prism as shown in the figure. A screen S is placed on the other side of the prism, facing AC. On turning the prism slowly, a beautiful band of colours is obtained on the screen. It is the spectrum of sunlight. (a) Name the phenomenon due to which a prism splits the incident white light into a band of colours. (b) State the reason of getting a band of seven colours in the above case.
(a) The phenomenon is called dispersion of light. (b) White light is a mixture of seven colours. Each colour has a different wavelength and, hence, is refracted (bent) by the glass prism through different angles, resulting in a band of seven distinct colours. (c) To show recombination of spectrum ofRead more
(a) The phenomenon is called dispersion of light.
(b) White light is a mixture of seven colours. Each colour has a different wavelength and, hence, is refracted (bent) by the glass prism through different angles, resulting in a band of seven distinct colours.
(c) To show recombination of spectrum of white light, Newton used two prisms. The first prism disperses white light into seven colours. When this spectrum is passed through a second, inverted prism, it recombines the seven colours back into white light.
Labelled Ray Diagram:
See lessRakvi performed an activity by taking ethanoic acid and sodium hydrogen carbonate as shown in the diagram given below. The diagram shows an experimental setup where ethanol is oxidised to ethanoic acid using an oxidizing agent, producing CO2 gas sodium bicarbonate (NaHCO3) may be used to test the acidic nature of the product. Answer the following questions based on the given information: (i) What is the observable change when CO2 gas reacts with lime water in the in this experiment? (ii) Rakvi observed that a salt X is formed with the evolution of gas Y. Identify the salt X and evolved gas Y. (iii) Write the chemical equation of the reaction involved.
(a) Lime water turns milky because carbon dioxide gas reacts with calcium hydroxide solution to form calcium carbonate. Calcium carbonate is insoluble in water and appears as a white precipitate, giving the solution a milky appearance. This reaction is a common laboratory test for the presence of caRead more
(a) Lime water turns milky because carbon dioxide gas reacts with calcium hydroxide solution to form calcium carbonate. Calcium carbonate is insoluble in water and appears as a white precipitate, giving the solution a milky appearance. This reaction is a common laboratory test for the presence of carbon dioxide gas.
(b) When ethanoic acid reacts with sodium hydrogen carbonate, the products formed are sodium ethanoate (X), water, and carbon dioxide gas (Y). The reaction demonstrates the typical acid–carbonate reaction, producing effervescence due to carbon dioxide release. The sodium salt formed is soluble, while the gas evolved can turn lime water milky.
(c) Carbon dioxide released from the reaction is confirmed using lime water. It reacts with calcium hydroxide to form insoluble calcium carbonate, which makes the solution appear milky. The balanced reaction is:
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O. This simple test is widely used to detect carbon dioxide gas.
See lessA student sitting on the last bench can read the letters written on the blackboard but is not able to read the letters written in his text book. Which of the following statements is correct?
ANSWER: [A] Explanation: Correct option: (a) The near point of his eyes has receded away. The student can clearly see the blackboard but cannot read his textbook, which means he suffers from hypermetropia (farsightedness). In this defect, the near point of the eye shifts farther away than normal, maRead more
ANSWER: [A]
Explanation: Correct option: (a) The near point of his eyes has receded away. The student can clearly see the blackboard but cannot read his textbook, which means he suffers from hypermetropia (farsightedness). In this defect, the near point of the eye shifts farther away than normal, making nearby objects appear blurred.
See lessTo get an image of magnification – 1 on a screen using a lens of focal length 20 cm, the object distance must be:
ANSWER: [C] Explanation: Correct option: (c) 40 cm. To obtain an image of magnification M = − 1, the image must be real, inverted and of the same size as the object. This happens when the object is placed at twice the focal length of a convex lens. The given focal length is f = 20 cm. Hence, the objRead more
ANSWER: [C]
Explanation: Correct option: (c) 40 cm. To obtain an image of magnification M = − 1, the image must be real, inverted and of the same size as the object. This happens when the object is placed at twice the focal length of a convex lens. The given focal length is f = 20 cm. Hence, the object should be placed at 2f = 40 cm. At this position, the image is formed on the opposite side of the lens, also at 40 cm, with the same size as the object but inverted.
See lessThe aluminium sheets used in building roofs do not rust, but their surfaces turn dull over time. (i) Why does aluminium not rust like iron? (ii) How can the dull appearance of aluminium be prevented? (iii) Why is aluminium preferred for roofing over iron sheets?
(i) Aluminium forms a thin protective oxide layer (Al₂O₃) on its surface when exposed to air. This layer prevents further corrosion, unlike iron which forms rust (Fe₂O₃·xH₂O) that flakes off. (ii) The dull appearance can be prevented by polishing or anodizing the aluminium surface to maintain its shRead more
(i) Aluminium forms a thin protective oxide layer (Al₂O₃) on its surface when exposed to air. This layer prevents further corrosion, unlike iron which forms rust (Fe₂O₃·xH₂O) that flakes off.
(ii) The dull appearance can be prevented by polishing or anodizing the aluminium surface to maintain its shine and protect it from corrosion.
(iii) Aluminium is lightweight, corrosion-resistant, and durable, making it ideal for roofing, whereas iron sheets are heavier and prone to rusting, requiring more maintenance.
See less