Help with Balancing Equations?

Question

Choose the answer that shows a correctly balanced equation

1. 4Br2 2 KI -> I2 4KBr

2. Br2 2 KI -> I2 2 KBr

3. 2Br2 2 KI -> I2 4 KBr

Choose the answer that shows a correctly balanced equation

1. 3Mg Mn2O3->3MgO 2Mn

2. 2Mg Mn2O3->MgO 3Mn

3. Mg 2Mn2O3->MgO 2Mn

4. Mg 3Mn2O3->2MgO Mn

5. 3Mg Mn2O3->2MgO 3Mn

Choose the answer that shows a correctly balanced equation

1. 2 NaOH H2 SO4 -> Na2 SO4 2 H2 O

2. NaOH H2 SO4 -> Na2 SO4 2 H2 O

3. 2 NaOH H2 SO4 -> Na2 SO4 H2 O

Choose the answer that shows a correctly balanced equation

1. 2 C6 H14 21 O2 -> 12 CO2 14 H2 O

2. 2 C6 H14 19 O2 -> 12 CO2 14 H2 O

3. C6 H14 19 O2 -> 12 CO2 14 H2 O

I'm having so much trouble with this, if someone could help me out a bit and walk me through some of it too, that would be awsome!

Answer 1

2 C6 H14 + 21 O2 -> 12 CO2 + 14 H2 O