Calculate the volume of unit cell when metal having density $1 \mathrm{~g} \mathrm{~cm}^{-3}$ and molar mass $23 \mathrm{~g} \mathrm{~mol}^{-1}$ crystallises to form bec structure.

Which polymer is obtained from monomers using

Which from following elements belongs to the actinoids?

Which of the following rules states that it is impossible to determine simultaneously the exact position and exact momentum of an electron?