CLASS 10TH CHAPTER-1 SCIENCE MOST IMPORTANT MCQ'S

 CLASS 10TH CHAPTER-1 SCIENCE MOST IMPORTANT MCQ'S

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 on 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.    When ferrous sulphate is heated strongly it undergoes decomposition to form ferric oxide as a main product accompanied by a change in colour from:
 a. Blue to green.
 b. Green to blue.
 c. Green to brown.
 d. Green to yellow.

10.   Which of the following gases is used in the storage of fat and oil containing foods for a long time?
 a. Carbondioxide gas
 b. Nitrogen gas
 c. Oxygen gas
 d. Neon gas  

11.  Consider reaction: Na(s) + O₂(g) → Na₂O(s). Moles of sodium needed to balance equation would be
A) 1
B) 2
C) 3
D) 4

12.  Consider reaction: Na(s) + O₂(g) → Na₂O. Moles of oxygen needed to balance equation are
A) 1
B) 2
C) 3
D) 4

13.  In which of the given chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?
A) 2H₂ (l) + O₂ (l) → 2H₂O (g)
B) 2H₂ (g) + O₂ (l) → 2H₂O (g)
C) 2H₂ (g) + O₂ (g) → 2H₂O (l)
D) 2H₂ (g) + O₂ (g) → 2H₂O (g)

14.  An element X on exposure to moist air turns reddish-brown and a new compound Y is formed. The substances X and Y are
A) X = Fe, Y = Fe₂O₃
B) X = Ag, Y = Ag₂S
C) X = Cu, Y = CuO
D) X = Al, Y = Al₂O₃

15.  In which of the given, heat energy will be evolved?
A) Electrolysis of water
B) Dissolution of NH₄Cl in water
C) Burning of L.P.G.
D) Decomposition of AgBr in the presence of sunlight

16.  In which of the given, heat energy will be evolved?
A) Electrolysis of water
B) Dissolution of NH₄Cl in water
C) Burning of L.P.G.
D) Decomposition of AgBr in the presence of sunlight

17.  Which of the following are exothermic processes?
(a) Reaction of water with quick lime
(b) Dilution of an acid
(c) Evaporation of water
(d) Sublimation of camphor (crystals)
A) (A) & (B)
B) (B) & (C)
C) (A) & (D)
D) (C) & (D)

18.   A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple color of the solution fades and finally disappears. Which of the given equation is the correct explanation for the observation?
A) KMnO₄ is an oxidizing agent, it oxidizes FeSO₄
B) FeSO₄ acts as an oxidizing agent and oxidizes KMnO₄
C) The color disappears due to dilution, no reaction is involved
D) KMnO₄ is an unstable compound and decomposes in the presence of FeSO₄ to a colourless compound

19.   Solid calcium Oxide reacts vigorously with water to form calcium hydroxide accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form its solution called lime water. Which among the following is are true about slaking of lime and the solution formed?
(a) It is an endothermic reaction.
(b) It is exothermic reaction.
(c) The pH of the resulting solution will be more than seven.
(d) The pH of the resulting solution will be less than seven.
A) (A) & (B)
B) (B) & (C)
C) (A) & (D)
D) (C) & (D)

20.  The chemical formula of lead sulphate is
A) Pb₂SO₄
B) Pb(SO₄)₂
C) PbSO₄
D) Pb₂(SO₄)₃