Answer:
(a) A = 
(b) 
(c) 
(d) 
Solution:
As per the question:
Radius of atom, r = 1.95
Now,
(a) For a simple cubic lattice, lattice constant A:
A = 2r
A = 
(b) For body centered cubic lattice:


(c) For face centered cubic lattice:


(d) For diamond lattice:


The answer is A. Reactivity
hope this helps
Acceleration = (change in speed) / (time for the change.
change in speed = (ending speed) - (starting speed) = 9 m/s.
Acceleration = (9 m/s) / (period of 1) .
We don't know the units of the 'period of 1'.
If it means '1 second', then the acceleration is 9 m/s² .