What does it mean when a mineral has a definite chemical composition? select 2 choices.
it always occurs in pure form.
it always contains certain elements,
it cannot form from living or once living materials.
it always contains elements in definite proportions,
it cannot contain atoms from more than one element.

It always contains certain elements and it always contains certain elements in definite proportions.

Step-by-step explanation: A mineral has five characteristics which definite chemical composition is one of them so are natural occurring, inorganic, solid and ordered internal structure.

a.

step-by-step explanation:

step 1 distribute 2 to every term in the parentheses

step 2 add 10 on both sides of the equal sign