Which one of the following equations is properly balanced?
1) Sn+4HNO₃ → SnO₂+4NO₂+2H₂O
2) 2Na₂SO₄+3Bi(NO₃)3 → Bi2(SO₄)3+9NaNO₃
3) CH₃CHO+3O2 → 2CO₂⁺2H2