Which of the following reactions is a synthesis reaction?

$\mathrm{Pb}({\mathrm{NO}}_3{)}_2+{\mathrm{Fe}}_2({\mathrm{SO}}_4{)}_3\to \mathrm{Fe}({\mathrm{NO}}_3{)}_3+ {\mathrm{PbSO}}_4$.

Coefficients of lead sulphate and ferric nitrate in the balanced equation of the above reaction are

Write the names of the salts formed by the reaction of the following:

(i) $\mathrm{Ca}$ and ${\mathrm{HNO}}_3$ and (ii) $\mathrm{Ca}$ and ${\mathrm{H}}_2{\mathrm{SO}}_3$. 

A, B and C are the elements such that A on reaction with air produces a dazzling white flame, B is used in rubber industry for hardening and C acts as a conductor with rise in temperature. Then A, B and C are: