PH=-log[H⁺]
pH=-log(1.87×10⁻¹³)
pH=12.72
I hope this helps. Let me know if anything is unclear.
The answer is 5.8x10^-10. I did the math and checked other sources as well.
Answer : The balanced equation for the complete combustion of cyclopentane will be :

Explanation :
As we know that the hydrocarbons can undergo complete or incomplete combustion that depends on the amount of oxygen available.
Complete combustion : It takes place when there is a good supply of oxygen. In this, hydrocarbon react with the oxygen to give carbon dioxide and water as a product.
The general reaction will be :

Incomplete combustion : It takes place when there is a poor supply of oxygen. In this, hydrocarbon react with the oxygen to give carbon monoxide, carbon dioxide and water as a product.
The general reaction will be :

As per question, the complete combustion of cyclopentane react with oxygen to gives carbon dioxide and water as a product.
Therefore, the balanced chemical reaction will be :

Answer:
C. Mole
Explanation:
Chemical formula deals with mole number
Hydrochloric acid is a mixture. Although we use HCl as the formula for hydrochloric acid, HCl is, in fact, the formula of hydrogen chloride, which is a compound. Hydrogen chloride is a gas which readily reacts with water.
HCl + H2O ———-> H3O^+(aq) and Cl^-(aq)
Hydrochloric acid is a mixture of these ions
H2O and H3O^+(aq) and Cl^-(aq)
There are many different concentrations of hydrochloric acid - it must be a mixture.