1
MCQ (Single Correct Answer)

AIPMT 2007

The correct order of increasing thermal stability of K2CO3, MgCO3, CaCO3 and BeCO3 is
A
BeCO3 < MgCO3 < CaCO3 < K2CO3
B
MgCO3 < BeCO3 < CaCO3 < K2CO3
C
K2CO3 < MgCO3 < CaCO3 < BeCO3
D
BeCO3 < MgCO3 < K2CO3 < CaCO3

Explanation

As the basicity of metal hydroxides increases down the group from Be to Ba, the thermal stability of their carbonates also increases in the same order. Further group 1 compounds are more thermally stable than group 2 because their hydroxide are much basic than group 2 hydroxides therefore, the order of thermal stability is

BeCO3 < MgCO3 < CaCO3 < K2CO3
2
MCQ (Single Correct Answer)

AIPMT 2006

The correct order of the mobility of the alkali metal ions in aqueous solution is
A
Rb+ > K+ > Na+ > Li+
B
Li+ > Na+ > K+ > Rb+
C
Na+ > K+ > Rb+ > Li+
D
K+ > Rb+ > Na+ > Li+

Explanation

Ionic radii of alkali metals in water follows the order
Li+ > Na+ > K+ > Rb+ > Cs+

Thus in aqueous solution due to larger ionic radius Li+ has lowest mobility and hence the correct order of ionic mobility is

Rb+ > K+ > Na+ > Li+
3
MCQ (Single Correct Answer)

AIPMT 2004

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
A
Ca(HCO3)2
B
CaCO3
C
Na2CO3
D
K2CO3

Explanation

The given compound X must be CaCO3.

4
MCQ (Single Correct Answer)

AIPMT 2002

In which of the following processes, fused sodium hydroxide is electrolysed at a 330oC temperature for extraction of sodium?
A
Castner's process
B
Down's process
C
Cyanide process
D
Both 'b' and 'c'

Explanation

In Castner’s process, for production of sodium metal, sodium hydroxide (NaOH) is electrolysed at temperature 330ºC.

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