A cubic solid is made of two elements P and Q. Atoms of Q are at the corners of the cube and P at the body-centre.

Given. Atoms of Q are the corners of the cube and P at the body- centre 

Therefore, Number of atoms of Q in one unit cell =8×1/8=1

Number of atoms of P in one unit cell =1

Therefore, Ratio of P and Q atoms = P:Q = 1:1

Therefore, formula of the given compound = PQ

Since it is bcc 

Therefore, coordinate number of P and Q = 8