Common table salt becomes moist and does not pour easily in rainy season because:

1. It contains magnesium chloride.

2. It contains magnesium carbonate.

3. It melts slightly in rainy season.

4. Sodium chloride is hygroscopic.

Excess of dilute sodium hydroxide solution is gradually added with shaking to an aqueous solution of zinc sulphate. What would you observe?

1. A light blue precipitate is first formed which finally dissolves to give a deep blue solution

2. A white precipitate appears which dissolves to give a colourless solution.

3. A white precipitation is formed which does not dissolve 

4. No change takes place and the solution remains clear

The products of the electrolysis of aqueous solution of common salt are:

1. Na + Cl₂

2. H₂ + O₂

3. NaOH + H₂ + Cl₂

4. NaOH + Cl₂ + O₂

KO₂ is used in oxygen cylinder in space air craft and submarines because it:

1. absorbs CO₂ and increase O₂ content

2. eliminate moisture

3. absorbs CO₂

4. produces O₂

Potash alum is used in purification of water because:

1. it kills the micro-organisms

2. it precipitates the colloidal matter

3. it removes the hardness of water

4. it catalyses the removal of impurities

Manufacture of NaOH is done by:

1. Castner - Kellner process

2. Solvay process

3. Brine process

4. Mond's process

Lithium is the only alkali metal which is not placed in kerosene but is wrapped in paraffin wax, because:

1. it reacts with kerosene

2. it floats to the surface of kerosene because of low density

3. it does not react with air and H₂O

4. none of the above

When CO₂ is bubbled into an aqueous solution of Na₂CO₃, the following is formed:

1. H₂O

2. OH-

3. NaHCO₃

4. NaOH

The principal products obtained on heating iodine with concentrated caustic soda solution are:

1. NaOI + NaI

2. NaIO₃ + Nal

3. NaOI + NaIO₃ + NaI

4. NaIO₄ + NaI

Which of the following acts as reducing agent as well as oxidising agent?

1. Na₂O

2. Na₂O₂

3. NaNO₃

4. KNO₃