Analysis of Statement-I: Both
BeSO4 and
MgSO4 are readily soluble in water.
The solubility of sulfates of alkaline earth metals generally decreases down the group.
BeSO4 (Beryllium sulfate) is readily soluble in water. This is due to the very small size of the
Be2+ ion, which leads to very high hydration energy. This high hydration energy more than compensates for the relatively high lattice energy, making it highly soluble.
MgSO4 (Magnesium sulfate, commonly known as Epsom salt) is also readily soluble in water. Similar to beryllium, the
Mg2+ ion is relatively small, leading to significant hydration energy.
In contrast,
CaSO4 (Calcium sulfate) is sparingly soluble, and
SrSO4 (Strontium sulfate) and
BaSO4 (Barium sulfate) are practically insoluble.
Therefore, Statement - I is correct.
Analysis of Statement - II: Among the nitrates of alkaline earth metals, only
Be(NO3)2 on strong heating gives its oxide,
NO2 and
O2.
Alkaline earth metal nitrates decompose on strong heating to give the metal oxide, nitrogen dioxide (
NO2 ), and oxygen
(O2). The general reaction is:
2M(NO3)2(s)| ‌ heat ‌ |
| ‌───────▶‌ |
2MO(s)+4NO2(g)+O2(g)This decomposition pattern is observed for all alkaline earth metal nitrates.
‌Be(NO3)2| ‌ heat ‌ |
| ‌───────▶‌ |
BeO+2NO2+‌O2‌Mg(NO3)2| ‌ heat ‌ |
| ‌───────▶‌ |
MgO+2NO2+‌O2‌Ca(NO3)2| ‌ heat ‌ |
| ‌───────▶‌ |
CaO+2NO2+‌O2And similarly for
Sr(NO3)2 and
Ba(NO3)2.
The thermal stability of these nitrates generally increases down the group
(Be(NO3)2. is the least stable, and
Ba(NO3)2 is the most stable), meaning they decompose at different temperatures, but the decomposition products are the same for all of them.
The statement claims that "only
Be(NO3)2 " decomposes in this manner, which is incorrect as all alkaline earth metal nitrates follow this decomposition pathway.
Therefore, Statement - II is not correct.
Conclusion:
Statement - I is correct.
Statement - II is not correct.
This matches option B.