C. is the answer. i know because i had this question not that long ago.
The answer is B, they differ greatly from the properties of all their elements. For example: Water is non-flamable but it is made from hydrogen, which is highly flammable, and oxygen, a gas that supports combustion.
5 examples of gases found in the normal home environment include; oxygen (air), nitrogen (most abundant element found in the air), carbon (air), a slight trace of argon and finally, hydrogen. these are- Nitrogen, oxygen, carbondioxide, carbonmonoxide and SO2.
First blank is: Half-Life
Second Blank is: decay into its products