Which from following elements belongs to group 17 of periodic table?

What is the number of moles of donor atoms in n mole of NO$$^-_2$$ ?

Calculate the density of an element having molar mass $$27 \mathrm{~g} \mathrm{~mol}^{-1}$$ that forms fcc unit cell. $$\left[\mathrm{a}^3 \cdot \mathrm{N}_{\mathrm{A}}=38.5 \mathrm{~cm}^3 \mathrm{~mol}^{-1}\right]$$

Which of the following is not a globular protein?