A. Iron combines with oxygen and water from the air to form rust. If an iron nail were allowed to rust completely, one should find that the rust weighs:
(a) less than the nail it came from.
(b) the same as the nail it came from.
(c) more than the nail it came from.
(d) It is impossible to predict.
B. What is the reason for your answer?
(a) Rusting makes the nail lighter.
(b) Rust contains iron and oxygen.
(c) The nail flakes away.
(d) The iron from the nail is destroyed.
(e) The flaky rust weighs less than iron.