Science : Ch 01 – Chemical Reactions and Equations

Give an example of decomposition reaction taking place in our body.

What happens when sodium sulphate solution is added to barium chloride solution?

What type of reaction is represented by: A + BC → AC + B ?

Why are anti-oxidants added to fat and oil containing food items?

Why are oil and fat containing food items fushed with nitrogen while packing?

When hydrogen sulphide gas is passed through a blue solution of copper sulphate, the colour of the solution fades and a black precipitate is obtained.Why does the colour of the solution fades?

When hydrogen sulphide gas is passed through a blue solution of copper sulphate, the colour of the solution fades and a black precipitate is obtained.Write the chemical name of the black precipitate formed.

Mention whether it is a physical or chemical changes: -Evaporation of petrol

Mention whether it is physical or chemical changes: Sublimation of solid ammonium chloride

Sate the reactions exothermic or endothermic in nature: Dissolution of sodium hydroxide in water

In the electrolysis of water, name the gases liberated at cathode

Solid calcium oxide reacts vigorously with water to form calcium hydroxide, accompanied by liberation of heat. This process is called slaking of lime. Calcium hydroxide dissolves in water to form a solution called lime water. Which among the following is (are) true about slaking of lime and the solution formed?

1. It is an endothermic reaction
2. It is an exothermic reaction.
3. The pH of the resulting solution will be more than seven.
4. The pH of the resulting solution will be less than seven

Which of the subsequent is (are) an endothermic process(es)?

1. Dilution of sulphuric acid
2. Sublimation of dry ice
3. Condensation of water vapours
4. Evaporation of water

Calcium oxide reacts vigorously with water to produce slaked lime. CaO(s) + H₂O(l) → Ca(OH)₂(aq) This reaction can be classified as:

1. Combination reaction
2. Exothermic reaction
3. Endothermic reaction
4. Oxidation reaction

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

1. Displacement reaction
2. Combination reaction
3. Redox reaction
4. Neutralisation reaction