General Science
8th Class
Chapter 6
Chemical Reactions
Questions
1. Encircle the correct option.
(i) Carbon burns in air to release energy along with the formation of:
a. carbon dioxide b. carbon dioxide and water
c. carbon dioxide and hydrogen d. carbon monoxide and hydrogen
(ii) The products of the reaction between zinc and dilute sulphuric acid are:
a. zinc oxide and water b. zinc sulphide and water
c. zinc sulphate and hydrogen d. zinc sulphide and hydrogen
(iii) Which of the following is an unbalanced chemical equation?
a. CH4 (g) + 2O2 (g) → 2H2O (g) + CO2 (g)
b. Na (s) + Cl2 (g) → NaCl (s)
c. C (s) + Cu2O (s) → CO (g) + 2Cu (s)
d. C (s) + O2 (g) → CO (g)
iv. Heating of solid potassium chlorate produces a gas:
a. chlorine b. carbon dioxide c. carbon monoxide d. oxygen
v. Which of the following is an exothermic reaction?
a. Formation of iron sulphide by heating the mixture of iron and sulphur
b. Formation of nitric oxide by heating the mixture of nitrogen and oxygen
c. Formation of hydrogen iodide by heating the mixture of hydrogen and iodine
d. Formation of calcium oxide and carbon dioxide by heating calcium carbonate
vi. Which of the following is a balanced chemical equation?
a. Fe + 3Cl2 → 2FeCl3 b. Fe + 3Cl2 → FeCl3
c. 2Fe + 3Cl2 → 2FeCl3 d. Fe + Cl2 → FeCl3
vii. The following equation is properly balanced when.
x CO (g) + y O2 (g) → z CO2 (g)
a. x = 1, y = 2 and z =3 b. x = 2, y = 1 and z =1
c. x = 2, y = 2 and z =2 d. x = 2, y = 1 and z =2
viii. How many oxygen atoms are present in one molecule of Mg(HCO3)2?
a. 2 b. 4 c. 6 d. 8
ix. The reaction between calcium oxide and carbon dioxide to form calcium carbonate is an example of:
a. addition reaction b. decomposition reaction
c. acid-base reaction d. neutralization reaction
x. Thermal decomposition of calcium carbonate produces a gas:
a. oxygen b. carbon dioxide
c. nitrogen d. carbon monoxide
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