Both slicing a tomato and a chemical change such as burning toast cannot be reversed. however, why is slicing a tomato still considered only a physical change?

Physical changes do not change the chemical make up of a substance. Chemical changes do.

Slicing a tomato only changes its proportion and size (which are physical properties), instead of anything inside the tomato.

Meanwhile, burning toast changes something inside the toast, making it a chemical change, instead of a physical change.

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o