Answer:
C. 2NaOH + H₂SO₄ -> Na₂SO₄ + 2H₂O
Explanation:
Simply count up the elements in the reactants and the products, then compare.
Reactants:
2 Na = 2 Na
2 O + 4 O = 6 O
2 H + 2 H = 4 H
Products:
2 Na = 2 Na
4 O + 2 O = 6 O
2 x H₂ = 4 H
Because the constituent elements in the reactants = products, the law of conservation of mass is preserved. You can check the other 3 options to see that they will not equal each other.
Don't forget to distribute the coefficients to every part of the formula; on the other hand, subscripts only apply to the element they are under. If a coefficient needs to be multiplied to an element with a subscript, use the subscript instead of 1 (1 is when there are no subscripts).
