MCQ Questions for Class 10 Science Chemical Reactions and Equations with Answers
Class 10 science chapter 1 chemical reactions and equation is very important chapter of class 10 science here you can easily read MCQs of chapter 1 chemical reactions and equations as well as you can also download PDF of these MCQs.

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Question 1.
What happens when dilute hydrochloric acid is added to iron filling? 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 2.
Which of the following is a thermal decomposition reaction?
(a) 2H2O → 2H2 + O2
(b) 2AgCl → 2Ag + Cl2
(c) H2(g) + Cl2(g) → 2HCl(g)
(d) ZnCO3 → ZnO + CO2
Answer
(d) ZnCO3 → ZnO + CO2

Question 3.
The reaction between lead nitrate and potassium iodide present in aqueous solutions
is an example of
(a) Decomposition Reaction
(b) Displacement Reaction
(c) Double Displacement Reaction
(d) Neutralization Reaction
Answer
(c) Double Displacement Reaction

Question 4.
The condition produced by aerial oxidation of fats and oils in foods marked by
unpleasant smell and taste is called:
(a) Antioxidation
(b) Reduction
(c) Rancidity
(d) Corrosion
Answer
(c) Rancidity

Question 5.
The reaction between lead nitrate and potassium iodide present in aqueous solutions
is an example of
(a) Decomposition Reaction
(b) Displacement Reaction
(c) Double Displacement Reaction
(d) Neutralization Reaction
Answer
(c) Double Displacement Reaction

Question 6.
Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and
oxygen gases liberated during electrolysis of water is:
(a) 1:1
(b) 2:1
(c) 4:1
(d) 1:2
Answer
(b) 2:1

Question 7.
What type of chemical reactions take place when electricity is passed through water?
(a) Displacement
(b) Combination
(c) Decomposition
(d) Double displacement
Answer
(c) Decomposition

Question 8.
Which of the following is an endothermic process?
(a) Dilution of sulphuric acid
(b) Sublimation of dry ice
(c) Condensation of water vapours
(d) Respiration in human beings
Answer
(b) Sublimation of dry ice

Question 9.
Oxidation is a process which involves
(a) addition of oxygen
(b) addition of hydrogen
(c) removal of oxygen
(d) removal of hydrogen
Answer
(a) addition of oxygen

Question 10.
Give the ratio in which hydrogen and oxygen are present in water by volume.
(a) 1:2
(b) 1:1
(c) 2:1
(d) 1:8
Answer
(a) 1:2

Question 11.
A substance which oxidizes itself and reduces other is known as
(a) Oxidizing agent
(b) reducing agent
(c) Both (a) and (b)
(d) None of these.
Answer
(b) reducing agent

Question 12.
In an electrolytic cell where electrolysis is carried, anode has:
(a) Positive change
(b) Negative charge
(c) Connected to negative terminal of the battery
(d) None of these is correct
Answer
(a) Positive change

Question 13.
Which of the following reactions is not correct:
(a) Zn+ CuSO4 → ZnSO4 + Cu
(b) 2Ag + Cu(NO3)2 → 2AgNO3 + Cu
(c) Fe+CuSO4 → FeSO4 + Cu
(d) Mg + 2HCl → MgCl2 + H2
Answer
(b) 2Ag + Cu(NO3)2 → 2AgNO3 + Cu

Question 14.
Copper displaces which of the following metals from its salt solution:
(a) ZnSO4
(b) FeSO4
(c) AgNO3
(d) NiSO4
Answer
(c) AgNO3

Question 15.
Which of the following involves combination of two elements?
(a) N2(g) + 3H2(g) + 2NH3(g)
(b) Cao(s) + CO2(g) → CaCO3(g)
(c) 2SO2(g) + O2(g) → 2SO3f(g)
(d) NH3(g) + HCl(g) – NH4CI(S)
Answer
(a) N2(g) + 3H2(g) + 2NH3(g)

Question 16.
Some crystals of copper sulphate were dissolved in water. The colour of the solution
obtained would be:
(a) green
(b) red
(c) blue
(d) brown
Answer
(c) blue

Question 17.
When dilute HCl is added to zinc pieces taken in a test tube
(a) No change takes place
(b) the colour of the solution becomes yellow.
(c) A pungent smelling gas gets liberated.
(d) small bubbles of H2 gas appear on the surface of zinc pieces
Answer
(d) small bubbles of H2 gas appear on the surface of zinc pieces.

Question 18.
Magnesium ribbon is rubbed before burning because it has a coating of:
(a) basic magnesium oxide
(b) basic magnesium carbonate
(c) basic magnesium sulphide
(d) basic magnesium chloride
Answer
(b) basic magnesium carbonate

Question 19.
Which one of the following processes involve chemical reactions?
(a) Storing of oxygen gas under pressure in a gas cylinder
(b) Liquefaction of air
(c) Keeping petrol in a China dish in the open
(d) Heating copper wire in presence of air at high temperature
Answer
(d) Heating copper wire in presence of air at high temperature

Question 20.
Which of the following reactions will not take place?
(a) Zn + CuSO4 → ZnSO3 + Cu
(b) 2KBr + Cl2 →KCI+ Br2
(c) Zn + MgSO4 → ZnSO4 + Mg
(d) Mg + FeSO4 – MgSO4 + Fe
Answer
(c) Zn + MgSO4 → ZnSO4 + Mg

Question 21.
PbS reacts with ozone (O3) and forms pbso4. As per the balanced equation, molecules
of ozone required for every one molecule of PbS is/are
(a) 4
(b) 3
(c) 2
(d) 1
Answer
(a) 4

Question 22.
Chemically rust is
(a) Hydrated ferrous oxide
(b) hydrated ferric oxide
(c) only ferric oxide
(d) none of these
Answer
(b) hydrated ferric oxide

Question 23.
Heat is evolved during:
(a) Endothermic Reaction
(b) Displacement Reaction
(c) Combustion Reaction
(d) Combination Reaction
Answer
(c) Combustion Reaction

Question 24.
Dissolving sugar is an example of
(a) Physical change
(b) Chemical change
(c) Redox Reaction
(d) None of these.
Answer
(a) Physical change

Question 25.
A substance added to food containing fats and oils is called:
(a) Oxidant
(b) Rancid
(c) Coolant
(d) Antioxidant
Answer
(d) Antioxidant

Question 26.
Select the oxidizing agent for the following reaction:
H2S + I2 > 2HI + S
(a) I2
(b) H2S
(C) HI
(d) S
Answer
(a) I2

Question 27.
A substance ‘X’ is used in white-washing and is obtained by heating limestone in the
absence of air. Identify ‘X’.
(a) CaOCl2
(b) Ca(OH)2
(c) CaO
(d) CaCO3
Answer
(b) Ca(OH)2

Question 28.
Which of the following gases can be used for storage
(a) Carbon dioxide or Oxygen
(b) Nitrogen or Oxygen
(c) Carbon dioxide or Helium
(d) Helium or Nitrogen
Answer
(d) Helium or Nitrogen

Question 29.
When green coloured ferrous sulphate crystals are heated, the colour of the crystal
changes because:
(a) it is decomposed to ferric oxide
(b) it loses water of crystallization
(c) it forms SO2
(d) it forms SO3
Answer
(b) it loses water of crystallization

Question 30.
What is observed when a solution of potassium iodide is added to silver nitrate
solution?
(a) No reaction takes place
(b) White precipitate of silver iodide is formed
(c) yellow precipitate of Agl is formed
(d) Agl is soluble in water.
Answer
(c) yellow precipitate of Agl is formed

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