Question

Which of the following are soluble in water?
A. ${\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$
B. ${\text{Ba}}{{\text{C}}_{\text{2}}}{{\text{O}}_4}$
C. ${\text{MgC}}{{\text{O}}_{\text{3}}}$
D. ${\text{Ca(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}$

Answer 1

To answer this question we should know about solubility rules. Solubility rules tell which salts are soluble in water and which are not. The salts which are not soluble in water form solid and are known as a precipitate. The compound or salt which are soluble in water remains in ionized form.

Complete solution:
The solubility rules are as follows:
Ammonium${\text{NH}}_{\text{4}}^{\text{ + }}$, nitrate ${\text{NO}}_3^ -$ , chlorate ${\text{ClO}}_3^ -$ , and acetate${\text{C}}{{\text{H}}_{\text{3}}}{\text{CO}}{{\text{O}}^ - }$ are soluble.
Halides ${{\text{X}}^ - }$ are soluble.
Alkali metal and ammonia salts are soluble.
Oxalates ${{\text{C}}_{\text{2}}}{\text{O}}_4^{2 - }$ are insoluble.
Phosphate${\text{PO}}_4^{3 - }$, chromate ${\text{CrO}}_4^{2 - }$ and sulphide ${{\text{S}}^{2 - }}$ are insoluble.
Carbonates ${\text{CO}}_3^ -$ are insoluble except carbonates of alkali metal and ammonia.
Now let’s check the solubility of the given salts as follows:
According to the solubility rules, carbonates are insoluble but sodium is an alkali metal and the carbonate of alkali metal is soluble so, sodium carbonate ${\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$is soluble in water.
According to the solubility rules, oxalates are insoluble so, barium oxalate${\text{Ba}}{{\text{C}}_{\text{2}}}{{\text{O}}_4}$is insoluble in water.
According to the solubility rules, carbonates are insoluble so magnesium carbonate ${\text{MgC}}{{\text{O}}_{\text{3}}}$is insoluble in water.
According to the solubility rules, nitrates are soluble so, calcium nitrate ${\text{Ca(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}$is soluble in water.
So, sodium carbonate ${\text{N}}{{\text{a}}_{\text{2}}}{\text{C}}{{\text{O}}_{\text{3}}}$ and calcium nitrate ${\text{Ca(N}}{{\text{O}}_{\text{3}}}{{\text{)}}_{\text{2}}}$are soluble in water.

Thus, the correct option is (A).

Note: Solubility rules are given for the solubility of salt in water. It is necessary to remember the exceptions of general solubility rules. Halides are soluble except halides of silver, lead or mercury. Sulphates are soluble except the sulphates of strontium, barium, calcium, lead and mercury. Silver sulphates are slightly soluble.