Exercise: Chemical Reaction and Equations

Multiple Choice Questions

Which of the statements about the reaction below are incorrect?

2PbO(s) + C(s) → 2Pb(s) + CO₂(g)

  1. Lead is getting reduced
  2. Carbon dioxide is getting oxidised
  3. Carbon is getting oxidised
  4. Lead oxide is getting reduced

Fe₂O₃ + 2Al → Al₂O₃ + 2Fe

The above reaction is an example of a

What happens when dilute hydrochloric acid is added to iron fillings?

In the reaction 2FeCl₂ + Cl₂ → 2FeCl₃, chlorine is a

Rancidity can be prevented in food items by

Which among the following is not an oxidizing agent?

Which among the following gases are used to keep the oily food items fresh?

Chemically rust is

An exothermic reaction in which glucose combines with oxygen in the cells of our body and provides energy

Formula of lead sulphate is

What type of reaction is the reaction of calcium oxide with water?

KOH + H₂SO₄ → K₂SO₄ + H₂O

The above reaction is an example of

Fill in the Blanks

  1. ________ coloured powder is formed on burning magnesium ribbon in air.
  2. The formation of water by the reaction of H2(g) and O2(g) is a ________ reaction.
  3. Silver articles turn black on keeping in open due to the formation of ________.
  4. Silver chloride is stored in dark coloured bottles to prevent from ________.
  5. Oily and fatty food items become rancid due to ________.
  6. Those reactions in which heat is released along with the formation of products are called ________ reactions.
Answers

(1). White, (2). Combination, (3). Silver sulphide, (4). Sunlight, (5). Oxidation, (6). Exothermic

True/ False

  1. Dissociation reaction is opposite of combination reaction. (T/ F)
  2. The reaction of zinc oxide and copper is a redox reaction. (T/ F)
  3. Copper is a more reactive element as compared to zinc. (T/ F)
  4. Decomposition of vegetable matter to form compost is an endothermic reaction. (T/ F)
  5. On putting copper coins in silver nitrate solution, copper displaces silver. (T/ F)
  6. Corrosion and rancidity are redox reactions. (T/ F)
  7. Energy is absorbed is exothermic chemical reaction. (T/ F)
Answers

(1). True, (2). True, (3). False, (4). False, (5). True, (6). True, (7). False

One-Word Answer

  1. Name the chemical reaction in which heat is released
  2. What is the loss of electrons by an element, in a reaction called?
  3. Name the chemical reaction in which one reactant is oxidised and the other is reduced.
  4. In a double displacement reaction, what is exchanged between the reactants?
  5. In a chemical reaction, what does the symbol represent?
  6. What is the cause of change in taste and smell of oily and fatty food items?
  7. Why silver and gold items do not corrode?
  8. Write the name of equation in which there is an exchange of ions between the reactants.
  9. Who was proclaimed the emperor of unified Italy in 1861 ?
  10. Where were the statues of Marianne placed?
Answers

(1). Exothermic reaction, (2). Oxidation, (3). Redox reaction, (4). lons, (5). Formation of precipitate, (6). Becoming rancid due to oxidation, (7). Silver and gold are less reactive, (8). Double displacement reaction/Precipitation reaction

Match the column

Section ASection B
1). Respiration a). Calcium carbonate
2). Calcium oxide b). White powder
3). Magnesium oxide c). Quick lime
4). Decomposition of heat d). Absorption of heat
5). Endothermic reactione). Exothermic reaction
Answers

(1). > (e), (2). > (c), (3). > (b), (4). > (a), (5). > (d)