Final answer:
The mass of water formed during the combustion of the hydrocarbon is calculated by the subtraction of the mass of CO₂ produced from the total mass of reactants, which amounts to 22.5 g, making the correct answer A. 22.5 g.
Step-by-step explanation:
To determine the mass of water formed in the combustion of hydrocarbon, which requires 40 g of oxygen, resulting in products of CO₂ and water: We are given that after absorbing CO₂ the mass of lime water solution increases by 27.5 g, indicating the mass of CO₂ produced is 27.5 g.
According to the law of conservation of mass, the total mass of reactants equals the total mass of products. Given the initial mass of hydrocarbon (10 g) and oxygen (40 g), the total mass of reactants is 50 g.
If the mass of CO₂ produced is 27.5 g, the remaining mass must be of water since these are the only two products. Hence, the difference in mass gives us the mass of water produced: 50 g (total mass of reactants) - 27.5 g (CO₂) = 22.5 g of water. Therefore, the mass of the water formed is 22.5 g.
Thus, the answer to the multiple choice question is A. 22.5 g.