Question

valency of Mn in Mno2?

Answer 1

Since O is 2- in valency and there are 2 O in MnO2, the O2 component represents a total valency of 4- (2 x 2 = 4). For MnO2 to be electrically neutral in this format, Mn must have a valency of 4+.

Answer 2

Valency indicates the bonding capacity of any element in the given compound. It can be easily check with the charges on respective ions.

In $\mathrm{MnO_2}$, each O carries -2 charge. Since, there are two O atoms, total negative charge will be present is -4. Now to balance the negative charge on O atom, there should be same positive charge on Mn atom to make a neutral compound.

Hence, the valency of Mn should be +4 in $\mathrm{MnO_2}$ molecule.