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.

do your own work and don"t cheat.

step-by-step explanation:

the solution of the equation is 2.23 ⇒ answer b

step-by-step explanation:

* lets revise the meaning of exponential function

- the form of the exponential function is y = ab^x, where a ≠ 0, b > 0 ,  

  b ≠ 1, and x is any real number

- it has a constant base b

- it has a variable exponent x

- to solve an exponential equation, take the log or ln of both sides,  

  and solve for the variable

* lets solve the problem

∵

- the base is 7 and the exponent is x

- insert ㏑ in both sides

∴

- use the rule

∴ x ㏑(7) = ㏑(77)

- to find x divide both sides by ㏑(7)

∴

* the solution of the equation is 2.23 to the nearest 2 decimal places