$\mathrm{Y}\stackrel{∆,205°\mathrm{C}}{\leftarrow }{\mathrm{CaSO}}_4.2{\mathrm{H}}_2\mathrm{O}\stackrel{∆,120°\mathrm{C}}{\to }\mathrm{X}$, X and Y

are respectively

1. Plaster of paris, dead burnt plaster

2. Dead burnt plaster, plaster of paris

3. CaO and plaster of paris

4. Plaster of paris, mixture of gases

Which of the following compounds are paramagnetic in nature ?

1. ${\mathrm{K}}_2\mathrm{O}$

2. ${\mathrm{K}}_2{\mathrm{O}}_2$

3. ${\mathrm{Na}}_2{\mathrm{O}}_2$

4. ${\mathrm{RbO}}_2$

The order of melting point of chlorides of alkali metals is

1. LiCl > NaCl > KCl > CsCl

2. LiCl > NaCl > KCl > CsCl

3. NaCl > KCl > CsCl > LiCl

4. LiCl > NaCl > CsCl > KCl

The aqueous solutions of lithium salts are poor conductor of electricity rather than other alkali metals because of 

1. High ionisation energy

2. High electronegativity

3. Lower ability of ${\mathrm{Li}}^{+}$ ions to 
   polarize water molecules

4. Higher degree of hydration of 
    ${\mathrm{Li}}^{+}$ ions

${\mathrm{Be}}_2\mathrm{C}+{\mathrm{H}}_2\mathrm{O}\to \mathrm{BeO}+\mathrm{X}$
${\mathrm{CaC}}_2+{\mathrm{H}}_2\mathrm{O}\to \mathrm{Ca}{\left(\mathrm{OH}\right)}_2+\mathrm{Y}$

then X and Y respectively

1. ${\mathrm{CH}}_4, {\mathrm{CH}}_4$

2. ${\mathrm{CH}}_4, {\mathrm{C}}_2{\mathrm{H}}_6$

3. ${\mathrm{CH}}_4, {\mathrm{C}}_2{\mathrm{H}}_2$

4. ${\mathrm{C}}_2{\mathrm{H}}_2,{\mathrm{CH}}_4$

Which of the following statements are false ?

1. ${\mathrm{BeCl}}_2$ is a linear molecule in the vapour state
    but it is polymeric form in the solid state

2. Calcium hydride is called hydrolith

3. Carbides of both Be and Ca react with water
    to form acetylene

4. Oxides of both Be and Al are amphoteric 

The compound (s) formed upon combustion of sodium metal in excess air is (are)

1. ${\mathrm{Na}}_2{\mathrm{O}}_2$

2. ${\mathrm{Na}}_3\mathrm{N}$

3. ${\mathrm{NaO}}_2$

4. NaOH

The suspension of slaked lime in water is known as

1. Lime water

2. Quick lime

3. Milk of lime

4. Washing of lime

In context with beryllium, which one of the following statements is incorrect?

1.  It is rendered passive by nitric acid

2.  It forms ${\mathrm{Be}}_2\mathrm{C}$

3. Its salts rarely hydrolyse

4.  Its hydride is electron-deficient and polymeric

Which of the following oxides is most acidic in nature?

1. MgO

2. BeO

3. BaO

3. CaO