Share & grow the world's knowledge!
We want to connect the people who have knowledge to the people who need it, to bring together people with different perspectives so they can understand each other better, and to empower everyone to share their knowledge.
The 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 lessA carbon compound X is a good solvent. On reaction with sodium, X forms two products Y and Z. Z is used to convert vegetable oil into vegetable ghee. Identify and name X, Y and Z. Also write the equation of reaction of X with sodium to justify your answer.
The compound X is ethanol, which is a good solvent. When ethanol reacts with sodium, it forms two products: Y, which is sodium ethoxide, and Z, which is hydrogen gas. The hydrogen gas produced is used in the hydrogenation of vegetable oils to convert them into vegetable ghee. The reaction can be repRead more
The compound X is ethanol, which is a good solvent. When ethanol reacts with sodium, it forms two products: Y, which is sodium ethoxide, and Z, which is hydrogen gas. The hydrogen gas produced is used in the hydrogenation of vegetable oils to convert them into vegetable ghee. The reaction can be represented as ethanol reacting with sodium to produce sodium ethoxide and hydrogen gas, showing the displacement of hydrogen from ethanol by the metal sodium.
See lessDuring a laboratory experiment, a student compared the reactivity of aluminium, sodium and lead with dilute hydrochloric acid. He added small pieces of each metal into separate test tube containing HCl and observed: • Aluminium caused the solution to heat up. • Sodium reacted vigorously with flames. • Lead produced Bubbles slowly. (a) Explain the reason for the rise in temperature when aluminium reacts with dilute HCl. (b) Give a reason why the reaction of sodium with dilute HCl is extremely vigorous. (c) State why the reaction of lead with dilute HCl is slow and produces only a few bubbles.
ANSWER: (a) The temperature rises because aluminium reaction with dilute HCl in an exothermic reaction, releasing heat along with hydrogen gas. (b) Sodium reacts extremely vigorously with HCl because it is highly reactive, producing hydrogen gas rapidly with heat that can ignite the gas and causingRead more
ANSWER: (a) The temperature rises because aluminium reaction with dilute HCl in an exothermic reaction, releasing heat along with hydrogen gas.
(b) Sodium reacts extremely vigorously with HCl because it is highly reactive, producing hydrogen gas rapidly with heat that can ignite the gas and causing a vigorous reaction.
(c) Lead reacts slowly with dilute HCl because it is less reactive, so hydrogen gas is released gradually, forming only a few bubbles.
See less