Question

what is the answer plz explain

Answer 1

firstly we have to find the valency of the metal,
M2O3 =>>>
write the valency of metal =x
valency of Oxygen =-2

as there are two atoms of metal =2X
2X+3(-)=0
2X -6=0
2X =6
X=3

valency of this metal is 3.

✳Then option third is correct here.
MX3,
because valency of halogen is -1.