NYC Regents Exam Jan 2023
Which substance contains elements chemically combined in a fixed proportion?
(1) manganese
(2) methane
(3) silicon
(4) strontium
Solution: Compound is a substance that contains elements chemically combined in a fixed proportion. Manganese, silicon and strontium are all elements (can be found on the Periodic Table). Methane is the only compound and is therefore the correct answer 2.