Question

Which of the following is the best example of the law of conservation of mass?

• A. 12 g of carbon combines with 32 g of oxygen to form 44 g of carbon dioxide.
• B. When 12 g of carbon is heated in a vacuum, there is no change
  in mass.
• C. A sample of air increases in volume when heated at constant pressure but its mass remains unaltered.
• D. The weight of a piece of platinum is the same before and after heating in air.

Answer 1

The correct option is A 12 g of carbon combines with 32 g of oxygen to form 44 g of carbon dioxide.

$12\text{g}+32\text{g}=44\text{g}$
Mass of reactants and products should be equal to each other, in accordance with the law of conservation of mass.