What is the correct order with respect to metallic property of Zr, Cd, Sn, Sr?

Identify the number of molecules in which the central atom has one lone pair of electrons from the following list.

$$ \mathrm{PbCl}_2, \mathrm{PH}_3, \mathrm{ClF}_3, \mathrm{SF}_4, \mathrm{BF}_3, \mathrm{SnCl}_2 $$

In which of the following molecules, the number of lone pairs of electrons on central atom and the number of $d$-orbitals involved in the hybridisation of central atom, is same?

4 g of an ideal gas $A$ (molar mass $=M_A$ ) present in a vessel of volume $V$ litre exerted a pressure of 5 atm at 300 K . When 16 g of another ideal gas $B$(molar mass $=M_B$ ) was introduced into this vessel at the same temperature, its pressure increased to 10 atm . What is the correct relationship between $M_A$ and $M_B$ ?