Johannes Kepler- he did it by observing the ‘Tycho Brahe’. His 3rd law was published 10 years later to his first two laws.
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:


YES, ELECTRICITY CONCERNS ENERGY WHICH IS USED AS A FUEL . IN MODERN DAY TECH, MOST MACHINES USE ELECTRICITY AS A FUEL SUCH AS THE ELECTRONIC TRAIN IN TOKYO, JAPAN.