Jay had two clear liquids in bottles. the mass of one liquid was 10.2 grams and the other was 7.6 grams. when he mixed them, a yellow solid formed and settled to the bottom of the bottle. he predicted that the liquid plus the solid would have more mass, so he put the bottle on a scale. the mass was 17.8 grams. why did the mass not change?

The reason the mass did not change because he did not add anything to the mixture accept the two liquids and its not possble to change the mass/ weight of any certain weighted item like the which is heavier the 1 pound of feathers or the 1 pound of bricks the only things is that the brick has more density so there for neither one is heavier than the other because the are both a pound

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.