a) CH4+O2=CO2+H2O

Here, on reactant side,

C=1. H=4. and O=2

On product side,

C=1. O=2+1. and H=2

Therefore, multiply (H2O) by 2

Now, CH4+O2=CO2+2(H2O)=BALANCED EQUATION

b) PbO2=PbO+O2

Here, reactants,

Pb=1. O=2

And products,

Pb=1. O=1+2

Therefore, multiply (PbO) on product side by 2

PbO2=2(PbO)+O2

Now multiply (PbO2) on reactant side by 2

Therefore the balanced chemical equation is

2(PbO2)=2(PbO)+KE

c)Ca+N2=Ca3N2

Reactant,

Ca=1. N=2

Product,

Ca=3 N=2

Therefore multiply (Ca) on reactant side by 3

Hence the balanced chemical equation is

3(Ca)+N2=Ca3N2

d)N2+H2=NH3

Reactant,

N=2. H=2

Product,

N=1. H=3

Therefore multiply N on product side by 2

N2+H2=2(NH3)

Now multiply (H2) on reactant side by 3

Therefore the balanced chemical equation is

N2+3(H2)=2(NH3)

e) NaNO3=NaNO2+O2

Reactant,

Na=1. N=1. O=3

Product,

Na=1. N=1. O=2+2

Therefore multiply (NaNO3) on reactant side by 2

2(NaNO3)=NaNO2+O2

Now multiply (NaNO2) on product side by 2

Therefore the balanced chemical equation is

2(NaNO3)=2(NaNO2)+O2

Hope it HELPS u...!!!!....