Which oxide(s) of manganese have a mass percent of the metal that is greater than 50%? mno mno2 mn2o3all of these102

All of these

Explanation:

In MnO:

mass of Mn = 55 g (as 1 mole of Mn weighs 55 g)

mass of O = 16 g    (as 1 mole of O weighs 16 g)

The mass percent of metal Mn=

In MnO2:

mass of Mn = 55 g

mass of O = 2*16 = 32 g

The mass percent of metal Mn=

In Mn2O3:

mass of Mn = 2*55 = 110 g

mass of O = 3*16 = 48 g

The mass percent of metal Mn=

In all the cases the mass percent of metal is greater than 50.

d: the voltage of the secondary coil is less than that of the primary coil.

im not suree sorry if wrong