Crystals can be classified into how many basic crystal systems?

Write a short note on Bravais lattices.

Which of the following is true for $SnO_2$?

Identify the crystal system in which a primitive unit cell has edge lengths $a = b = 200 \text{ pm}$ and $c = 300 \text{ pm}$ and all axial angles are $90^{\circ}$.

If the distance between $Na^{+}$ and $Cl^{-}$ ions in sodium chloride crystal is '$Y$' $pm$, the length of the edge of the unit cell will be:

In a face-centred cubic $(FCC)$ unit cell,the edge length $(a)$ in terms of atomic radius $(r)$ is: