Available Answers

1. 1.

   Match the columns.

   Column A	Column B
   1. Nitrogen and hydrogen gas combining to form ammonia gas	a. Characteristic of a chemical reaction
   2. Water an passing electricity splits into hydrogen and oxygen	b. Heat producing reaction
   3. Exothermic reaction	c. Decomposition reaction
   4. Evolution of a gas	d. Condition of a chemical reaction
   5. Close contact	e. Combination reaction
   6. Rust	f. Product formed when iron is exposed to air and moisture

    

2. 2.

   Write the word equation for the formation of the following compounds.

   1. Iron(II) sulphide, by heating iron and sulphur.
   2. Magnesium oxide, by burning magnesium in air.
   3. Calcium oxide, by heating calcium in air
   4. Hydrogen chloride, by reacting hydrogen gas with chlorine gas
   5. Water, by reacting hydrogen and oxygen.
   6. Ammonia, by combining hydrogen and nitrogen.
3. 3.

   Write the word equation for the decomposition of the following compounds.

   1. Calcium carbonate
   2. Sodium chloride
   3. Water
   4. Lead bromide
   5. Potassium chlorate
   6. Magnesium carbonate
4. 4.

   Choose the correct option.

   1. Which one of the following is an example of decomposition reaction?
      1. Electricity passed through sodium chloride
      2. Reaction of hydrogen and oxygen in presence of electric current
      3. Burning magnesium in air
      4. Rusting of iron
   2. Which one of the following is an example of combination reaction?
      1. Formation of ammonia
      2. Electricity passed through water
      3. Mixing iron and sulphur
      4. Strongly heating calcium carbonate
   3. Which is a characteristic of a chemical reaction?
      1. Change in colour
      2. Change in state
      3. Evolution of smell
      4. All of these
   4. Which one of the following is not a condition for a chemical reaction to take place?
      1. No contact
      2. Catalyst
      3. Heat
      4. Light
   5. In a chemical reaction the reactant compound splits into its constituent elements or other compounds. Which type of reaction is this?
      1. Combination
      2. Decompositionn
      3. Combustion
      4. None of these.
5. 5.

   Complete the equations given below. Write a word equation for each.

   1. CaCO3 → ___________ + ___________	2. KClO3 → ___________+ __________
   3. NaCl → ____________ + ___________	4. PbBr2 → ___________ + __________
   5. H2 + Cl2 → ______________	6. H2 + O2 → __________
   7. Mg + O2 → ____________	8. Fe + S → _____________
   9. Fe + Cl2 → ______________	10. CO2 + H2O → ____________

    

6. 6.

   Match the columns.

   Column A	Column B
   1. Reactants	a. Exothermic reaction
   2. Products	b. Liberates ammonia on healing
   3. Conditions	c. Are written on the left-hand side
   4. Ammonium chloride with sodium hydroxide	d. Are written on the right-hand side
   5. Sodium hydroxide with hydrochloride acid	e. Are written on the top of or below the arrow