I would say its option number 2 and since its an ''ion'' it would be written as H3O+ :)
PH=-log[H⁺]
pH=-log(1.87×10⁻¹³)
pH=12.72
I hope this helps. Let me know if anything is unclear.
Answer:
Given the balanced equation
CH4 (g) + 2O2 (g) → CO2 (g) + 2H2O (g)
we know that we'll get one mole CO2 for every 1 mole CH4. So let's calculate how many moles are in 50 g of CH4 by dividing it's mass by it's molar mass (16 g/mole). I get 3.125 moles. The equation says we should get the same number of moles of CO2, so set moles CO2 = 3.125 moles. Then we can find the mass of CO2 by multipying by the molar mass of CO2 (44 g/mole). We should expect 138 grams of CO2.
Explanation: