Which from following alkenes is highly stabilized ?

Which of the following alkanes is NOT obtained when a mixture of ethyl iodide and n-propyl iodide is subjected to Wurtz reaction?

A compound forms hcp structure. What is the number of tetrahedral voids formed in 0.8 mol of it.

Calculate the number of atoms present in 90 g of metal if it forms bcc structure.
[ $\rho \times a^3 = 1.8 \times 10^{-22}$ g ]