What is the atomic radius of polonium if it crystallises in a simple cubic structure with edge length of unit cell $$336 \mathrm{~pm}$$ ?

Which among the following halides has triagonal bipyramidal structure?

Which among following compounds is used as monomer in preparation of Teflon?

Which of the following is NOT obtained when a mixture of bomomethane and bromoethane is treated with sodium in dry ether?