An element with molar mass 2.7 × 10?² kg mol?¹ forms a cubic unit cell with edge length 405pm. If its density is 2.7 × 10³ kg m?³, the radius of the element is approximately × 10?¹² m (to the nearest integer).

At 25°C the standard emf of cell having reactions involving two electrons change is found to be 0.295 V. The equilibrium constant of the reaction is :

Kindly consider the following 

Packing fraction of body centred cubic structure is      

Packing efficiency of fcc lattice is

The first co-ordination number of Cs⁺ in CsCl lattice is