Which of the following crystals has the unit cell such that $a=b \neq c$ and $\alpha=\beta=90^{\circ}$, $\gamma=120^{\circ}$ ?

The number of atoms in 4.5 g of a face-centred cubic crystal with edge length 300 pm is (Given : Density $=10 \mathrm{~g} \mathrm{~cm}^{-3}$ and $N_A=6.022 \times 10^{23}$)

If '$$a$$' stands for the edge length of the cubic systems. The ratio of radii in simple cubic, body centred cubic and face centred cubic unit cells is

Match the column A (type of crystalline solid) with the column B (example for each type)