CBSE Class 10 Science Chemical reactions and equations Sure Shot Questions Set 03

Question. Which of the following are chemical changes ?
(i) Digestion of food
(ii) Liquefaction of air
(iii) Ripening of fruit
(iv) Dissolution of sulphur in carbon disulphide
(v) Freezing of water
(vi) Electrolysis of water
(a) (i) to (iv) all
(b) (i), (iii) & (vi)
(c) (i), (iii) & (iv)
(d) (iii), (iv) & (vi)
Answer: (b) (i), (iii) & (vi)

Question. Which among the following is not a physical change?
(a) Melting of solid to liquid.
(b) Vaporisation of liquids to gas.
(c) Liquefaction of gases to liquid.
(d) Decay of matter.
Answer: (d) Decay of matter.

Question. Which among the following is not a chemical change?
(a) Melting of ice.
(b) Carbon cycle.
(c) Dehydration of substances.
(d) Fermentation of substances.
Answer: (a) Melting of ice.

Question. Physical changes are usually ________ in nature.
(a) temporary
(b) permanent
(c) irreversible
(d) endothermic
Answer: (a) temporary

Question. An example of a chemical change is ________.
(a) formation of clouds.
(b) glowing of an electric light.
(c) dropping sodium into water.
(d) dissolving of salt in water.
Answer: (c) dropping sodium into water.

Question. Which of these will cause a chemical change to occur ?
(a) Grinding of wheat into flour.
(b) Lighting of a gas stove.
(c) Evaporation of water from a lake.
(d) Ringing of an electric bell.
Answer: (b) Lighting of a gas stove.

Question. Chemical changes are ________.
(a) temporary, reversible and a new substance is produced.
(b) always accompanied by exchange of light.
(c) permanent, irreversible and a new substance is produced.
(d) never accompanied by exchange of light and heat energy.
Answer: (c) permanent, irreversible and a new substance is produced.

Question. Which of the following is a physical change?
(a) Solubility in water
(b) Combustibility
(c) Aerial oxidation
(d) Reaction with water
Answer: (a) Solubility in water

Question. Formation of carbon disulphide from carbon and sulphur takes place by
(a) absorption of heat
(b) evolution of heat
(c) no change in heat content
(d) None of the options
Answer: (a) absorption of heat

Question. In the equation \( Cu + xHNO_{3} \to Cu(NO_{3})_{2} + yNO_{2} + 2H_{2}O \), the values of x and y are
(a) 3 and 5
(b) 8 and 6
(c) 4 and 2
(d) 7 and 1
Answer: (c) 4 and 2

Question. Which of the following chemical equations is an unbalanced one ?
(a) \( 2NaHCO_{3} \to Na_{2}CO_{3} + H_{2}O + CO_{2} \)
(b) \( 2C_{4}H_{10} + 12O_{2} \to 8CO_{2} + 10H_{2}O \)
(c) \( 2Al + 6H_{2}O \to 2Al(OH)_{3} + 3H_{2} \)
(d) \( 4NH_{3} + 5O_{2} \to 4NO + 6H_{2}O \)
Answer: (b) \( 2C_{4}H_{10} + 12O_{2} \to 8CO_{2} + 10H_{2}O \)

Question. In the reaction given below, a, b, c and d respectively are
\( aFe_{2}O_{3} + bH_{2} \to cFe + dH_{2}O \)
(a) 1, 1, 2, 3
(b) 1, 1, 1, 1
(c) 1, 3, 2, 3
(d) 1, 2, 2, 3
Answer: (c) 1, 3, 2, 3

Question. When ferrous hydroxide reacts with hydrochloric acid, ________ and \( H_{2}O \) are produced.
(a) \( FeCl_{3} \)
(b) \( FeCl_{2} \)
(c) \( FeCl_{4} \)
(d) \( FeCl \)
Answer: (b) \( FeCl_{2} \)

Question. Which of the following is a combustion reaction ?
(a) Boiling of water
(b) Melting of wax
(c) Burning of petrol
(d) None of the options
Answer: (c) Burning of petrol

Question. The reaction, \( H_{2} + Cl_{2} \to 2HCl \) is
(a) an oxidation reaction
(b) a reduction reaction
(c) a combination reaction
(d) an isomerisation reaction
Answer: (c) a combination reaction

Question. Decomposition of water is
(a) electrolytic
(b) thermal
(c) photolytic
(d) All of the options
Answer: (a) electrolytic

Question. Which of the following is a decomposition reaction ?
(a) \( NaOH + HCl \to NaCl + H_{2}O \)
(b) \( NH_{4}CNO \to H_{2}NCONH_{2} \)
(c) \( 2KClO_{3} \to 2KCl + 3O_{2} \)
(d) \( H_{2} + I_{2} \to 2HI \)
Answer: (c) \( 2KClO_{3} \to 2KCl + 3O_{2} \)

Question. Which of the following is not a decomposition reaction ?
(a) \( CaCO_{3} \to CaO + CO_{2} \)
(b) \( 2KClO_{3} \to 2KCl + 3O_{2} \)
(c) Digestion of food in body
(d) \( H_{2} + Cl_{2} \to 2HCl \)
Answer: (d) \( H_{2} + Cl_{2} \to 2HCl \)

Question. Lead nitrate on heating gives
(a) Lead oxide
(b) Nitrogen dioxide
(c) Oxygen
(d) All of the options
Answer: (d) All of the options

Question. Heating limestone produces
(a) Quick lime
(b) Carbon dioxide
(c) Both (a) and (b)
(d) None of the options
Answer: (c) Both (a) and (b)

Question. When copper powder is heated, it gets coated with
(a) Black copper oxide
(b) Yellow copper oxide
(c) Red copper oxide
(d) None of the options
Answer: (a) Black copper oxide

Question. Which of the following equations is representing combination of two compounds ?
(a) \( CaO + CO_{2} \to CaCO_{3} \)
(b) \( CO + \frac{1}{2}O_{2} \to CO_{2} \)
(c) \( SO_{2} + \frac{1}{2}O_{2} \to SO_{3} \)
(d) \( 2Na + 2H_{2}O \to 2NaOH + H_{2} \)
Answer: (a) \( CaO + CO_{2} \to CaCO_{3} \)

Question. Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved ?
(i) Displacement reaction
(ii) Precipitation reaction
(iii) Combination reaction.
(iv) Double displacement reaction
(a) (i) only
(b) (ii) only
(c) (iv) only
(d) (ii) and (iv)
Answer: (d) (ii) and (iv)

Question. Which of the following is not a thermal decomposition reaction ?
(a) \( 2H_{2}O \to 2H_{2} + O_{2} \)
(b) \( 2FeSO_{4} \to Fe_{2}O_{3} + SO_{2} + SO_{3} \)
(c) \( ZnCO_{3} \to ZnO + CO_{2} \)
(d) \( 2KClO_{3} \to 2KCl + 3O_{2} \)
Answer: (a) \( 2H_{2}O \to 2H_{2} + O_{2} \)

Question. Which of the statements about the reaction below are incorrect ?
\( 2PbO(s) + C(s) \to 2Pb(s) + CO_{2}(g) \)
(i) Lead is getting reduced.
(ii) Carbon dioxide is getting oxidised.
(iii) Carbon is getting oxidised.
(iv) Lead oxide is getting reduced.
(a) (i) and (ii)
(b) (i) and (iii)
(c) (i), (ii) and (iii)
(d) All of the options
Answer: (a) (i) and (ii)

Question. What happens when dilute hydrochloric acid is added to iron filings ? Tick the correct answer.
(a) Hydrogen gas and iron chloride are produced.
(b) Chlorine gas and iron hydroxide are produced.
(c) No reaction takes place.
(d) Iron salt and water are produced.
Answer: (a) Hydrogen gas and iron chloride are produced.

Question. The reaction, \( Fe_{2}O_{3}(s) + 2Al(s) \to Al_{2}O_{3} + 2Fe(l) \) is an example of
(a) combination reaction
(b) double displacement
(c) decomposition reaction
(d) single displacement reaction
Answer: (d) single displacement reaction

Question. Which of the following is a displacement reaction?
(a) \( CaCO_{3} \to CaO + CO_{2} \)
(b) \( CaO + 2HCl \to CaCl_{2} + H_{2}O \)
(c) \( Fe + CuSO_{4} \to FeSO_{4} + Cu \)
(d) \( NaOH + HCl \to NaCl + H_{2}O \)
Answer: (c) \( Fe + CuSO_{4} \to FeSO_{4} + Cu \)

Question. Which of the following stands for a double displacement reaction ?
(a) \( 2H_{2} + O_{2} \to 2H_{2}O \)
(b) \( 2Mg + O_{2} \to 2MgO \)
(c) \( AgNO_{3} + NaCl \to AgCl + NaNO_{3} \)
(d) \( H_{2} + Cl_{2} \to 2HCl \)
Answer: (c) \( AgNO_{3} + NaCl \to AgCl + NaNO_{3} \)

Question. What amount of \( CO_{2} \) is evolved when 50g of \( CaCO_{3} \) is strongly heated ?
(a) 0.25 mol
(b) 0.35 mol
(c) 0.45 mol
(d) 0.5 mol
Answer: (d) 0.5 mol

Question. What happens when copper rod is dipped in iron sulphate solution ?
(a) Copper displaces iron.
(b) Blue colour of copper sulphate solution is obtained.
(c) No reaction takes place.
(d) Reaction is exothermic.
Answer: (c) No reaction takes place.

Question. A student added dilute HCl to a test tube containing zinc granules and made following observations :
I. The zinc surface became dull and black.
II. A gas evolved which burnt with a pop sound.
III. The solution remained colourless.
Correct observations are
(a) I and II
(b) I and III
(c) II and III
(d) I, II and III
Answer: (d) I, II and III

Question. A dilute solution of sodium carbonate was added to two test tubes—one containing dil \( HCl \) (A) and the other containing dilute \( NaOH \) (B). The correct observation was
(a) A brown coloured gas liberated in test tube A.
(b) A brown coloured gas liberated in test tube B.
(c) A colourless gas liberated in test tube A.
(d) A colourless gas liberated in test tube B.
Answer: (c) A colourless gas liberated in test tube A.

Question. \( AgNO_{3}(aq) + NaCl(aq) \to AgCl(s) + NaNO_{3}(aq) \) Above reaction is
(a) precipitation reaction
(b) double displacement reaction
(c) combination reaction
(d) Both (a) and (b)
Answer: (b) double displacement reaction

Question. \( Zn + (dil.) H_{2}SO_{4} \to ZnSO_{4} + H_{2} \) Above reaction is
(a) decomposition reaction.
(b) single displacement reaction.
(c) oxidation reaction.
(d) neutralisation reaction.
Answer: (b) single displacement reaction.

Question. When the gases sulphur dioxide and hydrogen sulphide mix in the presence of water, the reaction is \( SO_{2} + 2H_{2}S \to 2H_{2}O + 3S \). Here hydrogen sulphide is acting as
(a) an oxidising agent
(b) a reducing agent
(c) a dehydrating agent
(d) a catalyst
Answer: (b) a reducing agent

Question. \( CuO + H_{2} \to H_{2}O + Cu \), reaction is an example of
(a) Redox reaction
(b) Decomposition reaction
(c) Neutralisation
(d) Analysis reaction
Answer: (a) Redox reaction

Question. When a chemical species loses one or more electrons, it is said to have been
(a) oxidised
(b) reduced
(c) remain unchanged
(d) hydrolysed
Answer: (a) oxidised

Question. Combustion can be considered as
(a) oxidation
(b) reduction
(c) decomposition
(d) All of the options
Answer: (a) oxidation

Question. Which of the following is a redox reaction ?
(a) \( CaCO_{3} \to CaO + CO_{2} \)
(b) \( H_{2} + Cl_{2} \to 2HCl \)
(c) \( CaO + 2HCl \to CaCl_{2} + H_{2}O \)
(d) \( NaOH + HCl \to NaCl + H_{2}O \)
Answer: (b) \( H_{2} + Cl_{2} \to 2HCl \)