The correct  sequence of increasing order of density is:

1. Li < K< Na < Rb < Cs

2. Li < Na < K < Rb < Cs

3. Cs < Rb < K < Na < Li

4. K < Li < Na < Rb < Cs

Highly soluble hydroxide in water is formed by -

1. Ni²⁺

2. K⁺

3. Zn²⁺

4. Al³⁺

The strongest reducing agent among the following is:

1. K

2. Na

3. Al

4. Mg

When crystal of caustic soda is exposed to air, a liquid layer is deposited because:

1. crystal melts

2. crystal loses water

3. crystal absorbs moisture and CO₂

4. crystal sublimes

Brine is chemically:

1. conc. solution of Na₂CO₃

2. conc. solution of Na₂SO₄

3. conc. solution of NaCl

4. conc. solution of alum