Which of the following is a physical change?
A iron rusting under water
B copper turning green in the air
C solid iodine subliming into a gas
D hydrogen and oxygen producing water

C. solid iodine subliming into a gas

Explanation:

A physical change is a change that is reversible and can be reversed back into the original product. The atoms and molecules undergoes some rearrangement in the physical change. The process of change in the state of matters are placed under physical change. Solid iodine sublimes into purple gas on heating. The gas is then changed back to iodine crystals after being cooled. Hence, this is an example of a physical change.

law of conservation of matter

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation: