`A_(AgCl)^(oo)` can be obtained:

The number of ways in which ten candidates A_(1),A_(2),A_(3),A_(4),……,A_(10) can be arranged in a row if A_(1) is just above A_(2) then the number of ways are

The number of ways in which ten candidates A_(1),A_(2),A_(3),A_(4),……,A_(10) can be arranged in a row if A_(1) and A_(2) are next to each other is

Metallic silver can be obtained from AgCl by

AgCl is crystallized from molten AgCl containing a little CdCl_(2) . The solid obtained will have

The number of ways in which 10 condidates A_(1),A_(2),......,A_(10) can be ranked so that A_(1) is always above A_(2) , is