NTSE Level Questions on Chemical Reactions and Equations

Chemical Reactions and Equations is an important chapter in Class 10 Science. Here are some NTSE level questions on this topic:

1. Write the chemical equation for the reaction between magnesium and hydrochloric acid.

2. What is the difference between complete combustion and incomplete combustion? Give examples.

3. What is a redox reaction? Give an example.

4. Define the following terms: (a) Reactants, (b) Products, (c) Catalyst.

5. Write the balanced chemical equation for the reaction between sodium hydroxide and hydrochloric acid.

6. What is the law of conservation of mass? Explain with an example.

7. What is an exothermic reaction? Give an example.

8. What is the difference between a physical change and a chemical change? Give examples.

9. Write the balanced chemical equation for the reaction between calcium carbonate and hydrochloric acid.

10. What is the difference between an acid and a base? Give examples.

Explanation:

1. The chemical equation for the reaction between magnesium and hydrochloric acid is:

Mg + 2HCl → MgCl2 + H2

2. Complete combustion is when a substance burns completely in the presence of oxygen to produce carbon dioxide and water. Examples: Burning of methane gas. Incomplete combustion is when a substance burns in the presence of limited oxygen to produce carbon monoxide and water. Examples: Burning of wood.

3. Redox reaction is a type of chemical reaction in which one substance is oxidized (loses electrons) and another substance is reduced (gains electrons). Example: Zn + CuSO4 → ZnSO4 + Cu

4. (a) Reactants: The substances that undergo a chemical reaction. (b) Products: The substances that are formed as a result of a chemical reaction. (c) Catalyst: A substance that speeds up a chemical reaction without being used up in the process.

5. The balanced chemical equation for the reaction between sodium hydroxide and hydrochloric acid is:

NaOH + HCl → NaCl + H2O

6. The law of conservation of mass states that in a chemical reaction, the total mass of the reactants is equal to the total mass of the products. For example, when burning a candle, the wax and oxygen react to produce carbon dioxide and water. The total mass of the reactants (wax and oxygen) is equal to the total mass of the products (carbon dioxide and water).

7. An exothermic reaction is a chemical reaction that releases heat. Example: Burning of wood.

8. A physical change is a change in which the substance retains its original properties. Examples: Melting of ice, boiling of water. A chemical change is a change in which the substance undergoes a chemical reaction and forms new substances. Examples: Burning of wood, rusting of iron.

9. The balanced chemical equation for the reaction between calcium carbonate and hydrochloric acid is:

CaCO3 + 2HCl → CaCl2 + CO2 + H2O

10. An acid is a substance that donates hydrogen ions (H+) in a solution. Examples: Hydrochloric acid, sulfuric acid. A base is a substance that accepts hydrogen ions (H+) in a solution. Examples: Sodium hydroxide, ammonia.

Divine