A compound which can be used in space vehicles both to absorb CO₂ and liberate O₂ is

1. NaOH

2. Na₂O

3. Na₂O₂  

4. CaO + NaOH

$\left(\mathrm{Yellow} \mathrm{ppt}\right)\stackrel{K_{2}Cr{O}_4}{\leftarrow }X\stackrel{dil. HCl}{\to }\left(\mathrm{Yellow} ppt\right)$
$\mathit{+}Z\mathit{\uparrow }\mathit{(}\mathit{p}\mathit{u}\mathit{n}\mathit{g}\mathit{e}\mathit{n}\mathit{t}\mathit{ }\mathit{s}\mathit{m}\mathit{e}\mathit{l}\mathit{l}\mathit{i}\mathit{n}\mathit{g}\mathit{ }\mathit{g}\mathit{a}\mathit{s}\mathit{)}$

If X gives 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 pair of compounds, which cannot exist together in a solution is 

1. ${\mathrm{NaHCO}}_3 \mathrm{and} \mathrm{NaOH}$

2. ${\mathrm{Na}}_2{\mathrm{CO}}_3 \mathrm{and} \mathrm{NaOH}$

3. ${\mathrm{NaHCO}}_3 \mathrm{and} {\mathrm{Na}}_2{\mathrm{CO}}_3$

4. ${\mathrm{NaHCO}}_3 \mathrm{and} {\mathrm{H}}_2\mathrm{O}$

${\mathrm{Mg}}_2{\mathrm{C}}_3+{\mathrm{H}}_2\mathrm{O}\to \mathrm{X} \left(\mathrm{organic} \mathrm{compound}\right)$ compound X is 

1. ${\mathrm{C}}_2{\mathrm{H}}_2$

2. ${\mathrm{CH}}_4$

3. Propyne

4. Ethene

Solution of sodium metal in liquid ammonia 

is a strong reducing agent due to presence of

1. Solvated sodium ions

2. Solvated hydrogen ions

3. Sodium atoms or sodium hydroxide

4. Solvated electrons

The order of solubility of lithium halides in non-polar solvents follows the order

1. LiI > LiBr > LiCl > LiF

2. LiF > LiI > LiBr > LiCl

3. LiCl > LiF > LiI > LiBr

4. LiBr > LiCI > LiF > LiI

Highly pure dilute solution of sodium in ammonia

1. Shows blue colouration due to solvated electrons

2. Shows electrical conductivity due to solvated sodium ions only

3. Shows red colouration due to solvated electrons but a bad 
    conductor of electricity

4. Produces hydrogen gas or carbonate

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