ANSWER: [A] Explanation: In test tube P: Copper sulphate solution reacts with zinc (Zn), because zinc is more reactive than copper. Zinc displaces copper from and copper is deposited as a red-brown coating on the zinc strip. In test tube Q: Magnesium sulphate solution does not react with zinc becauRead more
ANSWER: [A]
Explanation: In test tube P: Copper sulphate solution reacts with zinc (Zn), because zinc is more reactive than copper. Zinc displaces copper from and copper is deposited as a red-brown coating on the zinc strip.
In test tube Q: Magnesium sulphate solution does not react with zinc because zinc is less reactive than magnesium, so no displacement occurs.
ANSWER: [B] Explanation: An alkali is a base that dissolves in water hence, all alkalies are bases but all bases are not alkalies. Sodium hydroxide is termed as alkali as it is a strong base as well as highly soluble in water. Ferric hydroxide is also a base, but it is not an alkali as it is not solRead more
ANSWER: [B]
Explanation: An alkali is a base that dissolves in water hence, all alkalies are bases but all bases are not alkalies. Sodium hydroxide is termed as alkali as it is a strong base as well as highly soluble in water. Ferric hydroxide is also a base, but it is not an alkali as it is not soluble in water.
ANSWER: [C] Explanation: Sodium carbonate decahydrate (Washing soda: ) is used to remove the permanent hardness of water. Sodium carbonate decahydrate, also called washing soda, is used to remove permanent hardness of water.
ANSWER: [C]
Explanation: Sodium carbonate decahydrate (Washing soda: ) is used to remove the permanent hardness of water. Sodium carbonate decahydrate, also called washing soda, is used to remove permanent hardness of water.
Explanation: Both the Assertion (A) and Reason (R) are true, but the Reason does not correctly explain the Assertion. Baking soda is used in soda-acid fire extinguishers because it reacts with sulphuric acid (H₂SO₄) to release carbon dioxide (CO₂) gas. The released CO₂ helps extinguish fire by displRead more
Explanation: Both the Assertion (A) and Reason (R) are true, but the Reason does not correctly explain the Assertion. Baking soda is used in soda-acid fire extinguishers because it reacts with sulphuric acid (H₂SO₄) to release carbon dioxide (CO₂) gas. The released CO₂ helps extinguish fire by displacing oxygen around it, which is essential for combustion, thereby effectively putting out the fire. Correct option is (B).
ANSWER: Observations to justify chemical change: Effervescence (bubbling) is observed due to the evolution of hydrogen gas when zinc reacts with dilute sulphuric acid. Zinc granules gradually dissolve and a new substance, zinc sulphate solution, is formed. Hence, gas evolution and formation of a newRead more
ANSWER: Observations to justify chemical change:
Effervescence (bubbling) is observed due to the evolution of hydrogen gas when zinc reacts with dilute sulphuric acid.
Zinc granules gradually dissolve and a new substance, zinc sulphate solution, is formed.
Hence, gas evolution and formation of a new product confirm that a chemical change has taken place.
A zinc strip is added to two test tubes: test tube ‘P’ contains aqueous copper sulphate (CuSO4) and test tube Q contains aqueous magnesium sulphate MgSO4. Which of the following observations is correct? (a) In test tube ‘P’, zinc strip is coated with a red – brown layer, while in ‘Q’ there is no reaction. (b) Zinc strip turns black in ‘P’ and develops a white coating in ‘Q’. (c) Bubbles are observed in both test tubes ‘P’ and ‘Q’. (d) There is no reaction in either test tube.
ANSWER: [A] Explanation: In test tube P: Copper sulphate solution reacts with zinc (Zn), because zinc is more reactive than copper. Zinc displaces copper from and copper is deposited as a red-brown coating on the zinc strip. In test tube Q: Magnesium sulphate solution does not react with zinc becauRead more
ANSWER: [A]
Explanation: In test tube P: Copper sulphate solution reacts with zinc (Zn), because zinc is more reactive than copper. Zinc displaces copper from and copper is deposited as a red-brown coating on the zinc strip.
In test tube Q: Magnesium sulphate solution does not react with zinc because zinc is less reactive than magnesium, so no displacement occurs.
See lessSodium hydroxide is termed an alkali while Ferric hydroxide is not because:
ANSWER: [B] Explanation: An alkali is a base that dissolves in water hence, all alkalies are bases but all bases are not alkalies. Sodium hydroxide is termed as alkali as it is a strong base as well as highly soluble in water. Ferric hydroxide is also a base, but it is not an alkali as it is not solRead more
ANSWER: [B]
Explanation: An alkali is a base that dissolves in water hence, all alkalies are bases but all bases are not alkalies. Sodium hydroxide is termed as alkali as it is a strong base as well as highly soluble in water. Ferric hydroxide is also a base, but it is not an alkali as it is not soluble in water.
See lessThe name of the salt used to remove permanent hardness of water is:
ANSWER: [C] Explanation: Sodium carbonate decahydrate (Washing soda: ) is used to remove the permanent hardness of water. Sodium carbonate decahydrate, also called washing soda, is used to remove permanent hardness of water.
ANSWER: [C]
Explanation: Sodium carbonate decahydrate (Washing soda: ) is used to remove the permanent hardness of water. Sodium carbonate decahydrate, also called washing soda, is used to remove permanent hardness of water.
See lessAssertion (A): Baking soda is used in soda-acid fire extinguisher. Reason (R): On heating, it releases carbon dioxide which helps extinguish fire.
Explanation: Both the Assertion (A) and Reason (R) are true, but the Reason does not correctly explain the Assertion. Baking soda is used in soda-acid fire extinguishers because it reacts with sulphuric acid (H₂SO₄) to release carbon dioxide (CO₂) gas. The released CO₂ helps extinguish fire by displRead more
Explanation: Both the Assertion (A) and Reason (R) are true, but the Reason does not correctly explain the Assertion. Baking soda is used in soda-acid fire extinguishers because it reacts with sulphuric acid (H₂SO₄) to release carbon dioxide (CO₂) gas. The released CO₂ helps extinguish fire by displacing oxygen around it, which is essential for combustion, thereby effectively putting out the fire. Correct option is (B).
See lessA student performs the following experiment in his school laboratory. List two observations to justify that in this experiment a chemical change has taken place.
ANSWER: Observations to justify chemical change: Effervescence (bubbling) is observed due to the evolution of hydrogen gas when zinc reacts with dilute sulphuric acid. Zinc granules gradually dissolve and a new substance, zinc sulphate solution, is formed. Hence, gas evolution and formation of a newRead more
ANSWER: Observations to justify chemical change:
Hence, gas evolution and formation of a new product confirm that a chemical change has taken place.
See less