Hey there!
balanced chemical reaction:
2 H₂ (g) + 1 O₂ ( g ) ----------> 2 H₂O ( g )
Reagents :
H = 2 * 2 = 4
O = 1 * 2 = 2
----------------------
total = 4 + 2 => 6
Products:
H = 2 * 2 = 4
O = 2 * 1 = 2
___________
total = 4 + 2 => 6
Hope this helps