Please help me with my quiz?

1.) Which coefficients balance this equation?

_H2 + _N2 -> _NH3

A1, 2, 3

B2, 3, 2

C3, 1, 2

D4, 1, 3

2.) Which chemical equation is balanced?

AK2O + H2O -> KOH

BK2O + H2O -> 2KOH

CK2O + 2H2O -> 2KOH

D2K2O + 2H2O -> 2KOH

3.) Which chemical equation is balanced?

ACO2 + 4H2 -> CH4 + 2H2O

B4CO2 + H2 -> CH4 + 2H2O

CCO2 + 4H2 -> 2CH4 + 2H2O

D2CO2 + 2H2 -> 2CH4 + 2H2O

4.) Which coefficients balance this equation?

_CH4 + _O2 -> _CO2 + _H2O

A1, 1, 1, 1

B1, 1, 2, 1

C1, 2, 1, 2

D2, 1, 2, 1

5.) Which coefficients balance this equation?

_Al + _O2 -> _Al2O3

A2, 3, 1

B3, 2, 2

C4, 2, 2

D4, 3, 2