This is not chemistry but it's A, off top.
Answer:
a mixture of molecules - Box f
atoms of a pure elementa metal - Box D
a solid compound - Box C
a mixture of elements - Box A
Explanation:
Box a has mixture of elements which forms a solid like shape but there are different elements present in the box. The box f has mixture of molecules in which many atoms are combined together. Box c has solid compound with single element.
Answer:
For the first oxide, 1 g gives 0.888 g of copper.
Dividing by 0.888 tells us that 1.126 g gives 1 g of copper so has 0.126 g of oxygen.
For the second oxide, 1 g gives 0.798 g of copper.
Dividing by 0.798 tells us that 1.253 g gives 1 g of copper so has 0.253 g of oxygen.
So 1 g of copper combines with either 0.126 g or 0.253 g of oxygen.
Within the limits of experimental error, 0.253 is twice 0.126, confirming the law of multiple proportion.
The mass number is the number of protons added to the number of neutrons in an atom. Its that simple!
If this carbon isotope has 6 neutrons and 6 protons, 6 + 6 = 12. Therefore it has a mass number of 12.
