$$Mg$$ burns in air and produces a mixture of nitride and oxide.
2.
All alkali halides are soluble in water except $$LiF.$$ The low solubility of $$LiF$$ in water is due to its $$\underline {\left( {\text{i}} \right)} $$ the low solubility of $$CsI$$ is due to $$\underline {\left( {{\text{ii}}} \right)} .$$ $$LiF$$ is soluble in $$\underline {\left( {{\text{iii}}} \right)} $$ solvents.
The low solubility of $$LiF$$ in water is due to its high lattice enthalpy whereas the low solubility of $$CsI$$ is due to smaller hydration enthalpy of two large size ions. $$LiF$$ is soluble in non - polar solvents like ethanol, acetone, etc.
3.
When alkaline earth metals dissolve in ammonia, they form coloured solution like alkali metals. Which of the following observations regarding the reaction are correct?
(i) Dilute solutions are bright blue in colour due to solvated electrons.
(ii) These solutions decompose to form amides and hydrogen.
(iii) From this solution the ammoniates $${\left[ {M{{\left( {N{H_3}} \right)}_6}} \right]^{2 + }}$$ can be recovered by evaporation.
Permanent hardness of water is due to chlorides and sulphates of calcium and magnesium i.e $$CaC{l_2},CaS{O_4},MgC{l_2}\,{\text{and}}\,MgS{O_4}$$
7.
The solubility of alkali metal salts in water is due to the fact that the cations get hydrated by water molecules. The degree of hydration depends upon the size of the cation. If the trend of relative ionic radii is $$C{s^ + } > R{b^ + } > {K^ + } > N{a^ + } > L{i^ + }.$$ What is the relative degree of hydration?
Beryllium salts are covalent in nature because of very small size of $$B{e^{2 + }}\,ion$$ and its high polarising power, so it is easily hydrolysed.
e.g. $$BeC{l_2} + 2{H_2}O \to Be{\left( {OH} \right)_2} + 2HCl$$
10.
Identify $$W, X, Y$$ and $$Z$$ respectively in the given reactions.
\[CaC{{O}_{3}}\xrightarrow{\Delta }W+X\]
$$\eqalign{
& W + {H_2}O \to Y \cr
& Y + Z \to NaOH + CaC{O_3} \cr} $$