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
<span>PV=nRT Since P, V and R are constant, when T goes up, n must go down by the same factor </span>1:4
I think its A. because there are nuclear fusion and nuclear fission
