Question

plz tell me whether my answer is correct or wrong...its important
plz answer who know this numerical only,don't answer if u don't know....

Answer 1

First, it is bcc structure although you have written the value of Z correct.

Then, the value of value is given 288pm. You need to convert it into 'cm' which gives a= 288 * 10^(-10) = 2.88 * 10^(-8)cm

Next mistake is that on the formula you have written a^3 but will calculating you have multiplied just by a

And you need to find the number of atoms present in 100g.

M = mass and not number of atoms

So, you will get 
x g = Na atoms
1g =Na/x
100g = Na * 100/x
And then you will get the answer.

Thankyou, Hope it helps :)