The standard on which the atomic mass unit is based is the mass of a
a. proton.
b. neutron.
c. chlorine-35 atom.
d. carbon-12 atom.

Answer;

D. carbon-12 atom

Explanation;

-One atomic mass unit is the mass that is exactly equal to one-twelfth the mass of one carbon-12 atom. Therefore, the mass of carbon-12 is 12 amu and this provides the standard that is used in measuring the atomic mass of all other elements.

-The atomic mass of carbon is 12.01 and not 12.00 in the periodic table.

-Due to the fact that there are more than one element for most naturally occurring elements, the average mass of the naturally occurring mixture of isotopes is taken while determining the atomic mass of an element.

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