Chemical Reactions and Equations Class 10 MCQs

A student has been collecting Silver coins and Copper coins. One day she observed a black coating on Silver coins and a green coating on Copper coins. Which chemical phenomenon is responsible for these coatings?

• corrosion

• rancidity

• redox

• none

A_______ coloured layer of copper appears onto the the surface of the zinc ribbon when reacted with copper sulphate.

• blue

• red

• white

• black

A/an ________reaction is characterised by the evolution of heat energy

Precipitation and neutralization reaction are example of

• Displacement reaction

• Double displacement reaction

• decomposition reaction

• direct combination reaction

Assertion (A) : Decomposition of vegetable matter into compost is an example of exothermic reactions.

Reason (R) : Exothermic reaction are those reactions in which heat is evolved

• a) Both A and R are true and R is the correct explanation of A

• b) Both A and R are true but R is not the correct explanation of A.

• c) A is true but R is false.

• d) A is false but R is true.

During photosynthesis, the light energy is converted to chemical energy that is later used by the green plants for their activities. This is an example of ________________ reaction.

• endothermic

• exothermic

• precipitation

• combination

What will be the values of the coefficients x, y, and z if the given chemical equation is balanced?

xFeCl₃ + yMgO→ Fe₂O₃ + zMgCl₂

• x = 3, y = 2, z = 3

• x = 3, y = 2, z = 2

• x = 2, y = 4, z = 3

• x = 2, y = 3, z = 3

In electrolysis of water (acidified), the gases that are evolved at anode and cathode respectively are _________ and _______.

(DO NOT TYPE *AND* IN ANSWER)

Which of the following reaction can also be termed as a thermal decomposition reaction?

• (a) Combination reaction

• (b) Decomposition reaction

• (c) Displacement reaction

• (d) Double displacement reaction

Calcium carbonate decomposes into calcium oxide and carbon dioxide. The reactant is:

• Calcium Carbonate

• Calcium oxide

• carbon dioxide

• water