Which of the following is correct? a. One molecule of methane reacts with two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water.
b. One gram of methane reacts with two grams of oxygen to produce one gram of carbon dioxide and two grams of water.
c. One mole of methane reacts with two moles of oxygen to produce one mole of carbon dioxide and 2 moles of water.
d. a and c are correct.

The correct option is d. a and c are correct.

Explanation:

First, we will write a balanced equation for the reaction between methane (CH₄) and oxygen (O₂).

The reaction between methane (CH₄) and oxygen (O₂) gives carbon dioxide (CO₂) and water (H₂O). The balanced equation for the reaction is shown below

CH₄ + 2O₂ → CO₂ + 2H₂O

The number beside each molecule on the reactant side indicates the number of the individual molecules required for complete reaction and also the number beside each molecule on the product side indicates the number of the individual molecules produces in the reaction.

This means,

One molecule of methane will react with two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water. Hence, option a is correct.

From,

Number of molecules = Number of moles × Avogadro's number

Since Avogadro's number is constant, hence, the equation also means,

One mole of methane will react with two moles of oxygen to produce one mole of carbon dioxide and two moles of water. Hence, option c is correct.

For the mass relationship,

Mass = Number of moles × Molar mass

Molar mass of methane = 12 + 1(4) = 16 g/mol;

∴1g of methane = 0.0625 mole

Molar mass of oxygen = 16 g/mol;

∴2g of oxygen = 0.125 mole

Molar mass of carbon dioxide = 12 + 16(2) = 44 g/mol;

∴1g of CO₂ = 0.02272 mole

Molar mass of water = 1(2) + 16 = 18 g/mol;

∴2g of water = 0.11111 mole

From the equation 0.0625 mole of methane reacts with 0.125 mole of oxygen to produce 0.0625 mole of carbon dioxide and 0.125 moles of water.

Hence, option b is not correct.