Question

1. choose all that apply. in order for elements to form a compound, which two things must happen? must be in definite proportions must physically combine must be in reciprocal proportions must chemically combine

Explanation:

A compound is formed when elements chemically combine in definite proportions. Physical combination forms mixtures. Reciprocal proportions is not a requirement for compound formation.

Answer:

must be in definite proportions, must chemically combine