Choose the correct option:
1. Before burning in air, the magnesium ribbon is cleaned by rubbing with a sand paper to:
(a) Make the ribbon surface shinier.
(b) Remove the layer of magnesium oxide from the ribbon surface.
(c) Remove the layer of magnesium carbonate from the ribbon surface.
(d) Remove the moisture from the ribbon surface.
2. In a chemical reaction between sulphuric acid and barium chloride solution the white precipitates
formed are of:
(a) Hydrochloric acid (b) Barium sulphate (c) Chlorine (d) Sulphur
3. The respiration process during which glucose undergoes slow combustion by combining with oxygen
in the cells of our body to produce energy, is a kind of:
(a) Exothermic process (b) Endothermic process
(c) Reversible process (d) Physical process
4. A chemical reaction does not involve:
(a) Formation of new substances having entirely different properties than that of the reactants
(b) Breaking of old chemical bonds and formation of new chemical bonds
(c) Rearrangement of the atoms of reactants to form new products
(d) Changing of the atoms of element into those of another element to form new products
5. One of the following processes does not involve a chemical reaction. That is:
(a) Melting of candle wax when heated (b) Burning of candle wax when heated
(c) Digestion of food in our stomach (d) Ripening of banana
6. It is necessary to balance a chemical equation in order to satisfy the law of:
(a) Conservation of motion (b) Conservation of momentum
(c) Conservation of energy (d) Conservation of mass
7. All the methods mentioned below can be used to prevent the food from getting rancid except:
(i) Storing the food in the air-tight containers
(ii) Storing the food in refrigerator
(iii) Keeping the food in clean and covered containers
(iv) Always touching the food with clean hands
(a) (i) and (ii) (b) (i) and (iii) (c) (i), (iii) and (iv) (d) (iii) and (iv)
8. Rusting of iron involves a chemical reaction which is a combination of:
(a) Reduction as well as combination reactions (b) Oxidation as well as combination reactions
(c) Reduction as well as displacement reactions (d) Oxidation as well as displacement reactions
9. Which of the following gas is used in the storage of fat and oil containing food for long time?
(a) CO2 (b) N2 (c) O2 (d) Neon
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Answer:
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7. σptíσn α
8. σptíσn c
9. σptíσn. d
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Answer:
HI FRIEND......
1. (c) Remove the layer of magnesium carbonate from the ribbon surface
2. (b) Barium Sulfate
3. (a) Exothermic process
4. (d) Changing of the atoms of on element into those of another element to form new products
5. (a) Melting of candle wax when heated
6. (d) Conservation of mass
7. (d) (iii) and (iv)
8. (b) Oxidation as well as combining reaction
9. (b) N2
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