Answer:
Cell Wall, Cell Membrane, Nucleus, Endoplasmic Reticulum (ER), and Ribosome.
Explanation:
Hopefully this helps :).
17) 8.4 / 20 x 100
18) 20 . 0.5150
19) 6,50% because (as you said) the law of definite proportions states that regardless of the amount, a compound is always composed of the same elements in the same proportion by mass
The answer is 9. Calcium nitrate is made up
of 3 different elements that equal 9 atoms.