The Total solution for NCERT class 6-12
Whichone of the following alkali metals gives hydrated salts?
(a)Li (b) Na (c) K (d) Cs
Answer - 31 : -
Smallerthe size of an ion, the more highly is it hydrated. Among the given alkalimetals, Li is the smallest in size. Also, it has the highest charge density andhighest polarising power. Hence, it attracts water molecules more strongly thanthe other alkali metals. As a result, it forms hydrated salts such as LiCl.2 H2O. The other alkali metalsare larger than Li and have weaker charge densities. Hence, they usually do notform hydrated salts.
Whichone of the alkaline earth metal carbonates is thermally the most stable?
(a) MgCO3 (b) CaCO3 (c) SrCO3 (d) BaCO3
Answer - 32 : -
Thermalstability increases with the increase in the size of the cation present in thecarbonate. The increasing order of the cationic size of the given alkalineearth metals is
Mg< Ca < Sr < Ba
Hence,the increasing order of the thermal stability of the given alkaline earth metalcarbonates is
MgCO3 < CaCO3 < SrCO3 < BaCO3