What type of reaction are these?

1) 2 MgI₂ + Mn(SO₃)₂ → 2 MgSO₃ +MnI₄

2) P₄ + 3 O₂ → 2 P₂O₃

3) SeCl₆ + O₂ → SeO₂ + 3 Cl₂

4) C₃H₆O + 4 O₂ → 3 CO₂ + 3 H₂O

Ibelieve it's temperature! i'm not 100% sure.

Answer:             1.0  × 10⁻⁵ msolution:                     as we know ph is given as,                                    ph  = -log [h⁺]and,                                    [h⁺]  =  10^-ph    (1)putting value of ph in eq. 1,                                    [h⁺]  =  10⁻⁵                                    [h⁺]  =  1.0  × 10⁻⁵ m

The answer is d for this question

Where? we need more.