a friend notices that a nail that was left outside for a few months seems larger and heavier than it was before. he says it disproves the law of conservation of mass. explain why he is wrong

For the reaction c6h14(g) & longrightarrow; c6h6(g) + 4h2(g), δp(h2)/δt was found to be 2.5 x 10-2 atm/s, where δp(h2) is the change in pressure of hydrogen. determine δp(c6h14)/δt for this reaction at the same time.