Which alkali metal has the lowest melting point and exists as a liquid  at 30 degree temp–

(1) Na                                                             

(2) K 

(3) Rb                                                             

(4) Cs

Two metals X and Y form covalent halides. Both halides can act as Lewis acids and a catalyst in Friedel Crafts reaction. Halide of X is polymer in the solid state and a dimer in the vapour state which decomposes to monomer at 1200 K. However, halide of Y is a dimer in vapour state and becomes ionic in polar solvent. X and Y are respectively.

(1) Be, Al                                             

(2) Al, Be

(3) Be, Ca                                             

(4) Mg, Ca

Solubility of sulphates in water decreases from $MgS{O}_4$ to $BaS{O}_4$. It is due to the fact that –

(1) Ionic nature increases

(2) Size of $M^{2+}$ ion increases

(3) Lattice energy decrease

(4) Hydration enthalpy of $M^{2+}$ ions decreases

In the Solvay process of manufacture of sodium carbonate, the raw materials used are :

1. Aqueous NaOH, $N{H}_3$ and $C{O}_2$

2. Molten NaOH, $N{H}_3$ and CO

3. Brine NaCl, $N{H}_3$ and CO

4. Brine NaCl, $N{H}_3$ and $C{O}_2$

A blue coluored solution of an alkali metal in liq NH₃ is due to the presence of -

1. ${\mathrm{M}}^{-}$atoms.                                         

2. ${\mathrm{M}}^{+}$ ions .

3. Solvated anions  .                           

4. Solvated electrons.

Alkali metal ions are- 

1. Diamagnetic and coloured.

2. Diamagnetic and colourless.

3. Paramagnetic and coloured.

4. Paramagnetic and colourless.

A compound X on heating gives a colourless gas. The residue is dissolved in water to obtain Y. Excess $C{O}_2$ is bubbled through an aqueous solution of Y, and Z is formed. Z on gentle heating gives back X. The compound X is-

1. ${\mathrm{CaCO}}_3$                                           

2. ${\mathrm{Na}}_2{\mathrm{CO}}_3$

3. ${\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}$                                 

4. ${\mathrm{K}}_2{\mathrm{CO}}_3$

A compound insoluble in acetic acid is  -

1. Calcium oxide.                    

2. Calcium carbonate.

3. Calcium oxalate.                      

4. Calcium hydroxide.

Assertion : s-block elements do not occur free in nature

Reason:  s-block elements are highly electropositive in nature.

1. Both A and R are true and R is the correct explanation of A.

2. Both A and R are true, but R is not the correct explanation of A.

3. A is true, but R is false.

4. Both A and R are false.

Which of the following is a false statement-

(1) Sodium oxide is more basic then magnesium oxide.

(2) Beryllium oxide is amphoteric

(3) The thermal stability of beryllium carbonate is more than that of calcium carbonate

(4) Beryllium is amphoteric