Which equations are balanced? check all that apply.

mg3n2 + h2o → 3mgo + 2nh3

c3h8 + 5o2 → 4h2o + 3co2

zn + 2hcl → zncl2 + h2

3ca(oh)2 + 2h3po4 → ca3(po4)2 + 6h2o

3h2so4 + 2fe → fe2(so4)3 + h2

4al + 3o2 → 2al2o3

The balance equations are:

Explanation:

We know that,

In the balance equation, the number of different atoms of elements  in the reactants is equal to the number of different of atoms of elements in the products.

So. The balance equations will be

These equation are balanced because in these equations, the number of different atoms of element are equal in the reactants and  the products.

if you already have the answer to (a), then just work out how many periods there are in 1 minute, and that's the answer to (c).