A compound contains atoms of three elements in A, B and C. If the oxidation number of A is +2, B is +5 and that of C is -2 , the possible formula of the compound is :

.The formula of a compound with elements A, B,C  will be of the form A_x B_yC_z  where x,y,z  are the atomicities of individual atoms respectively.
The oxidation numbers of the elements A,B,C  are  +2, +5and -2 respectively.
A compound is always neutral, so the oxidation number of the compound is zero. Hence, the net oxidation number of the individual atoms is zero. 
2x + 5y -2z= 0

Restricting it to conditions that maximum oxidation state could be +8 or -3 , by Hit and Trial method, the possible solutions of (x,y,z) could be (1,2,6) or (3,2,8). 

Both the sets are possible as the elements are unknown. Hence the compounds are A(BC3)₂ or  A3B2C8

Dear student,

Please find the attached solution to your problem.

 

Let us assume the molecular formula of compound is A_x B_yC_z  where x,y,z  are the atomicities of individual atoms respectively.

Since, it is a neutral compound, hence net charge on it should be zero.

Hence, 2x + 5y – 2z = 0

Applying hit and trial method, we get two sets of positive integral solutions (1,2,6) and (3,2,8)

Hence, The compound could be either of A(BC₃)₂ or A₃B₂C₈

 

Hope it helps.

Thanks and regards,

Kushagra