co2
nacl
hcl
these may all be classified as
a) elements and compounds.
b) elements and molecules.
c) elements and pure substances.
d) compounds and pure substances.

8.98 dm3 of hydrogen gas is collected at 38.8 °c. find the volume the gas will occupy at -39.9 °c if the pressure remains constant.

Suppose that some of the compound spilled out of the crucible after it was heated. would that cause the percent by mass of water in the compound determined by the experiment to be too low, too high, or unchanged? briefly explain your answer.

Can someone me out on this question for my national 5 chemistry homework