Density is mass divided by volume. Therefore, volume is mass divided by density.

Mass of reactants > mass of products
Answer:
All the numbers in a chemical formula are significant, It is because the numbers in a chemical formula denote the number of different atoms present in the particular compound.
For example in H2SO4 there are 2 H 1 S and 4 O. This means 1 H2SO4 has 2 hydrogen 1 sulphur and 4 oxygen.
#19 due to weathering and erosion the rock from the stream was smoothened and without as much the rock from deep underground was/is very rugged and natural.
#18 Due to wind patterns the sand dunes are blew around and the sands shift and fly around with nothing to keep the sand in place the sand can go long distances or come long distances.