1) Ca + H₂ →
Ca + H₂ = CaH₂
2) PbO + H₂→
PbO + H₂ = Pb + H₂O
3) P+ O₂ →
4P + 5O₂ = 2P₂O₅
4) C + O₂→
C + O₂ = CO₂
Ответ: Ca + H₂ = CaH₂; PbO + H₂ = Pb + H₂O; 4P + 5O₂ = 2P₂O₅; C + O₂ = CO₂