Plsss!! Which of the following equations is balanced?

Question 3 options:

1) 2H2 + O2 → 4H2O

2) 4Na + O2 → 2Na2O

3) Fe2O3 + H2 → 2Fe + 3H2O

4) CH4 + O2 → CO2 + H2O

Asap! how do you lengthen a pattern piece? (family and consumer science, sewing)

How many moles of lead are in 1.50 x 10^12 atoms of lead? could you explain the answer as well and not just give it to me i am refreshing for finals and i need to know how to do it

What is a number added in front of a formula in order to balance the equation