s-Block Elements · Question 33

The alkali metals form salt-like hydrides by the direct synthesis at elevated temperature. The thermal stability of these hydrides decreases in which of the following orders?

1. NaH > LiH > KH > RbH > CsH
2. LiH > NaH > KH > RbH > CsH
3. CsH > RbH > KH > NaH > LiH
4. KH > NaH > LiH > CsH > RbH

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

1. BeCO3 < MgCO3 < CaCO3 < K2CO3
2. MgCO3 < BeCO3 < CaCO3 < K2CO3
3. K2CO3 < MgCO3 < CaCO3 < BeCO3
4. BeCO3 < MgCO3 < K2CO3 < CaCO3

In which of the following the hydration energy is higher than the lattice energy?

1. MgSO4
2. RaSO4
3. SrSO4
4. BaSO4

The correct order of the mobility of the alkali metal ions in aqueous solution is

1. Rb+ > K+ > Na+ > Li+
2. Li+ > Na+ > K+ > Rb+
3. Na+ > K+ > Rb+ > Li+
4. K+ > Rb+ > Na+ > Li+

A solid compound X on heating gives CO2 gas and a residue. The residue mixed with water forms Y. On passing an excess of CO2 through Y in water, a clear solution Z is obtained. On boiling Z, compound X is reformed. The compound X is

1. Ca(HCO3)2
2. CaCO3
3. Na2CO3
4. K2CO3

In which of the following processes, fused sodium hydroxide is electrolysed at a temperature of 330 C for extraction of sodium?

1. Castner's process
2. Downs process
3. Cyanide process
4. Both (2) and (3)

Mg is present in

1. chlorophyll
2. haemoglobin
3. vitamin-D
4. vitamin-B