An alkali metals that forms only the normal oxide M₂O on heating in air is-

1. Rb

2. K

3. Li

4. Na

The correct order of  thermal stability of carbonates of Group 2 elements is-

1. ${\mathrm{BeCO}}_3<{\mathrm{MgCO}}_3<{\mathrm{CaCO}}_3<Sr{\mathrm{CO}}_3<{\mathrm{BaCO}}_3$

2. ${\mathrm{BeCO}}_3<{\mathrm{MgCO}}_3<{\mathrm{BaCO}}_3<{\mathrm{SrCO}}_3<{\mathrm{CaCO}}_3$

3. ${\mathrm{BaCO}}_3<{\mathrm{MgCO}}_3<{\mathrm{CaCO}}_3<Sr{\mathrm{CO}}_3<{\mathrm{BeCO}}_3$

4. ${\mathrm{BaCO}}_3<{\mathrm{CaCO}}_3<{\mathrm{MgCO}}_3<{\mathrm{SrCO}}_3<{\mathrm{BeCO}}_3$

 Superoxide is formed on heating with an excess of air by:-

1. Li, Na

2. Mg, Be

3. Na, K

4. K, Rb

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.

Solubility of alkaline earth metal sulphates in water decreases in the sequence:

1. Mg > Ca > Sr >Ba
2. Ca > Sr > Ba > Mg
3. Sr > Ca > Mg > Ba
4. Ba > Mg > Sr > Ca

Lithium salts are generally hydrated because they have :

1. High polarizing power.

2. High ionization enthalpy.

3. High electronegativity.

4. Low polarizing power.

The correct statement(s) about the structure of BeCl₂ is -
a. BeCl₂ (solid)- exists as polymer.
b. BeCl₂ (vapour)- exists as chlorobridged dimer.
c. BeCl2 has bent structure in the vapour phase.
1. a
2. a & b
3. b
4. b & c

The correct order of increasing thermal stability of K₂CO₃, MgCO₃, CaCO₃ and BeCO₃ is :

1. ${\mathrm{BeCO}}_3<{\mathrm{MgCO}}_3<{\mathrm{K}}_2{\mathrm{CO}}_3<{\mathrm{CaCO}}_3$

2. ${\mathrm{BeCO}}_3<{\mathrm{MgCO}}_3<{\mathrm{CaCO}}_3<{\mathrm{K}}_2{\mathrm{CO}}_3$

3. ${\mathrm{MgCO}}_3<{\mathrm{BeCO}}_3<{\mathrm{CaCO}}_3<{\mathrm{K}}_2{\mathrm{CO}}_3$

4. ${\mathrm{K}}_2{\mathrm{CO}}_3<{\mathrm{MgCO}}_3<{\mathrm{CaCO}}_3<{\mathrm{BeCO}}_3$

$\left(\mathrm{Yellow} \mathrm{ppt}\right)\stackrel{{\mathrm{K}}_2{\mathrm{CrO}}_4}{\leftarrow }\mathrm{X}\stackrel{\mathrm{dil}. \mathrm{HCl}}{\to }$
$\left(\mathrm{Yellow} \mathrm{ppt}\right) +\mathrm{Z}\uparrow (\mathrm{pungent} \mathrm{smelling} \mathrm{gas})$

If X gives a green flame test, then X is:

1. ${\mathrm{MgSO}}_4$

2. ${\mathrm{BaS}}_2{\mathrm{O}}_3$

3. ${\mathrm{CuSO}}_4$

4. ${\mathrm{PbS}}_2{\mathrm{O}}_3$

The correct statement(s) among the following options is/are: