Question

Please answer urgently!

Answer 1

I think it is c hope it helps

Answer 2

For question (7) here is the answer

# suppose A is the atom present at the corner of f.c.c. cube unit cell

As atom at corner of unit cell is shared by 8 different unit cell
hence only 1/8 th part of each corner atom present in one unit cell

in f. c. c. total 8 atoms are present at corners
ND 1 corner consist of 1/8 part of atom
But 1 atom is missing at corner hence only 7. R at corner.
hence total 7 corners consist of
➡ A= 1 / 8 ✖ 7 = 7 / 8 atoms

In the f. c. c. unit cell there are total six faces.
and B atoms are present at center of these faces

atom at center of each face of f. c. c. is shared by two unit cells and contribute 1/2 part to each unit cell .
hence total atoms at 6 facec in f. c. c.
➡ B = 1 / 2 ✖ 6 = 3

# therefore A = 7/ 8 ND B = 3
hence A : B = 7/8 : 3 = 7 : 24
hence A7 B24 is the answer

for 8 th question I have already given answer in another your question.