CBSE Class 10 Chapter 1 Chemical Reactions and Equations (Short answer type question & answer)

Q1: What is rust?

Answer: Rust is hydrated iron oxide called Ferric oxide (Fe2O3.xH2O). It is reddish brown in colour.

Q2: What is the chemical equation of Burning of magnesium in air?

Answer: Magnesium + oxygen -> Magnesium oxide
2Mg + O2 -> 2MgO

Q3: What is the nature of Magnesium oxide (MgO)?

Answer: Magnesium oxide is basic in nature.

Q4: What happens when Magnesium reacts with Oxygen?

Answer: When Magnesium reacts with Oxygen it forms Magnesium Oxide.
2Mg + O2 -> 2MgO

Q5: What is the colour of Magnesium Oxide?

Answer: White

Q6: What is the colour of magnesium?

Answer: Silvery white colour

Q7: What happens when Zinc (Zn) reacts with Dilute Sulphuric acid (H2SO4)?

Answer: When Zinc reacts with Dilute Sulphuric acid it forms Zinc Sulphate (ZnSO4) and release Hydrogen gas (H2).
Zn + H2SO4 -> ZnSO4 + H2

Q8: What happens when Zinc (Zn) reacts with Hydrochloric acid (HCl)?

Answer: When Zinc reacts with Dilute Hydrochloric acid it forms Zinc Chloride (ZnCl2) and release Hydrogen gas (H2).
Zn + HCl -> ZnCl2 + H2

Q9: What is the chemical formula of Lead Nitrate?

Answer: Pb(NO3)2

Q10: What is the chemical formula of Potassium Iodide?

Answer: KI

Q11: What happens when Lead Nitrate solution is mixed with Potassium Iodide solution?

Answer: Lead Nitrate solution reacts with Potassium Iodide solution and forms Lead Iodide and Potassium Nitrate. Lead Iodide is yellowish precipitation which is insoluble in water.
Pb(NO3)2 + KI -> PbI2 + KNO3

Q12: What is exothermic chemical reaction?

Answer: A chemical reaction in which heat is evolved is called exothermic chemical reaction.

Q13: What is endothermic chemical reaction?

Answer: A chemical reaction in which heat is required for reaction is called endothermic chemical reaction.

Q14: What is the nature of chemical reaction between Zinc and dilute hydrochloric acid?

Answer: Reaction between Zinc and dilute hydrochloric acid is exothermic in nature.

Q15: What is chemical equation?

Answer: Chemical equation is the representation of chemical reaction by the chemical formula of reactants and products.

Q16: On which side of chemical equation reactants are shown?

Answer: Left hand-side [LHS]

Q17: On which side of chemical equation products are shown?

Answer: Right hand-side [RHS]

Q18: What does meant by an arrowhead between reactants and products?

Answer: Arrowhead shows the direction of the reaction.

Q19: What are the types of chemical equation?

Answer: There are two types of chemical reaction:
- Balanced chemical reaction
- Unbalanced (Skeletal) chemical reaction

Q20: Which theory followed during a chemical reaction?

Answer: A chemical reaction follows the law of conservation of mass.