Science : Ch 01 – Chemical Reactions and Equations

Identify the reducing agent in the following reactions: 2H₂ + O₂ → 2H₂O

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.Name the type of reaction taking place.

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 physical or chemical changes : Heating of an iron rod to red hot

Mention whether it is physical or chemical changes :Curdling of milk

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

State the reactions are exothermic or endothermic in nature: Decomposition of ferrous sulphate

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

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

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

Strong heating of ferrous sulphate leads to the formation of a brown solid and two gases. This reaction can be designated as:

You are given the solution of lead nitrate. In order to obtain a yellow precipitate you should blend with it a solution of:

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

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 solutions contained in beakers A and B, whereas in the case of beaker C, the temperature of the solution fell. Which one of the following statement(s) is (are) correct?

1. In beakers A and B, exothermic process has occurred.
2. In beakers A and B, endothermic process has occurred
3. In beaker C, exothermic process has occurred
4. In beaker C, endothermic process has occurred.

Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of reaction involved?

1. Displacement reaction
2. Precipitation reaction
3. Combination reaction
4. Double displacement reaction