2. In a solid 'AB' having NaCl structure atoms occupy the corners of the cubic unit cell. If all the face centered atoms along one of the axis are removed then the resultant stoichiometry of the solid is ___________?

it is given that, A occupies  corners and face center of unit cell and it's like NaCl structure.. When no atoms is removed then , 

 number of atoms of A in the unit cell = (1/8 * 8) + (1/2* 6) = 4

 Number of atoms of B which occupies octahedral voids =  1+ ( 1/4 * 12) = 4 

Therefore formula  = A₄B₄ = AB ( Like NaCl)