Chemical Reactions and Equations

Chemical Reactions and Equations

by Sudhanshu Randad

Multiple Choice

Which of the following are exothermic processes?

(i) Reaction of water with quick lime

(ii) Dilution of an acid

(iii) Evaporation of water

(iv) Sublimation of camphor (crystals)

• (i) and (ii)

• (ii) and (iii)

• (i) and (iv)

• (iii) and (iv)

Multiple Choice

A teacher gave two test tubes to the students, one containing water and the other containing sodium hydroxide. She asked them to identify the test tube containing sodium hydroxide solution. Which one of the following can be used for the identification?

• Blue litmus

• Red litmus

• Sodium carbonate solution

• Dilute hydrochloric acid

Multiple Choice

Which of the following is NOT physical change?

• Boiling of water to give water vapour

• Melting of ice to give water

• Dissolution of salt in water

• Combustion of Liquefied Petroleum Gas (LPG)

Multiple Choice

The following reaction is an example of a 4NH₃(g) + 5O₂(g) → 4NO(g) + 6H₂O(g)

(i) displacement reaction

(ii) combination reaction

(iii) redox reaction

(iv) neutralization reaction

• (i) and (iv)

• (ii) and (iii)

• (i) and (iii)

• (iii) and (iv)

Multiple Choice

Which among the following is (are) double displacement reaction(s)?

• Pb + CuCl2 → PbCl₂ + Cu

• Na₂SO₄ + BaCl₂ → BaSO₄ + 2NaCl

• C + O₂ → CO₂

• CH₄ + 2O₂ → CO₂ + 2H₂O

Multiple Choice

Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is

• 1 : 1

• 2 : 1

• 4 : 1

• 1 : 2

Multiple Choice

In the double displacement reaction between aqueous potassium iodide and aqueous lead nitrate, a yellow precipitate of lead iodide is formed. While performing the activity if lead nitrate is not available, which of the following can be used in place of lead nitrate?

• Lead sulphate (insoluble)

• Lead acetate

• Ammonium nitrate

• Potassium sulphate

Multiple Choice

In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?

• 2H₂(l) + O₂(l) → 2H₂O(g)

• 2H₂(g) + O₂(l) → 2H₂O(l)

• 2H₂(g) + O₂(g) → 2H₂O(l)

• 2H₂(g) + O₂(g) → 2H₂O(g)

Fill in the Blank

Any reaction that produces a ………….. is called a precipitation reaction.

Fill in the Blank

The oxidation and reduction reaction are also called ………….. reactions.

Multiple Select

Which of the following statements about the given reaction are correct?

3Fe (s) + 4H₂O (g) → Fe₃O₄ (s) + 4 H₂ (g)

• Iron metal is getting oxidised

• Water is getting reduced

• Water is acting as reducing agent

• Water is acting as oxidising agent

Multiple Select

Which of the following are exothermic processes?

• Reaction of water with quick lime

• Dilution of an acid

• Evaporation of water

• Sublimation of camphor (crystals)

Multiple Select

Three beakers labelled as A, B and C each containing 25 ml of water were taken. A small amount of NaOH, anhydrous CuSO₄ and NaCl were added to the beakers A, B and C respectively. It was observed that there was an increase in the temperature of the solution contained in beakers A and B, whereas in case of beaker C, the temperature of the solution falls. Which one of the following statement(s) is (are) incorrect?

• In beakers A and B, exothermic process has occurred.

• In beakers A and B, endothermic process has occured.

• In beaker C exothermic process has occurred.

• In beaker C endothermic process has occurred.

Multiple Choice

MnO₂ + 4HCl → MnC₂ + 2H₂O + Cl₂

Identify the substance oxidized in the above equation.

• MnCl₂

• HCl

• H₂O

• MnO₂

Multiple Choice

A substance ‘X’ is used in white-washing and is obtained by heating limestone in the absence of air. Identify ‘X’.

• CaOCl₂

• Ca (OH)₂

• CaO

• CaCO₃