CBSE Class 10 Board Examination Practice Quiz

Question 1

Which of the following observations most clearly indicates that a chemical reaction has taken place when zinc granules are added to dilute hydrochloric acid?

Accepted Answer

The zinc granules become smaller and bubbles of a gas are produced

Question 2

What is the balanced equation for the reaction between magnesium and oxygen?

Accepted Answer

2Mg + O2 → 2MgO

Question 3

In the reaction MnO2 + 4HCl → MnCl2 + 2H2O + Cl2, which substance is oxidised?

Accepted Answer

HCl

Question 4

When lead nitrate solution is mixed with potassium iodide solution, a yellow precipitate is formed. Which equation correctly represents this reaction?

Accepted Answer

Pb(NO3)2 + 2KI → PbI2 + 2KNO3

Question 5

Which statement correctly explains why respiration is considered an exothermic reaction?

Accepted Answer

Glucose breaks down and releases energy along with carbon dioxide and water