ANSWER:
4 a) Specific elements have more than one oxidation state, demonstrating variable valency.
For example, the following transition metals demonstrate varied valence states: 
, 
, 
, etc.
Normal metals such as 
also show variable valencies. Certain non-metals are also found to show more than one valence state 
4 b) Isotopes are members of a family of an element that all have the same number of protons but different numbers of neutrons.
For example, Carbon-14 is a naturally occurring radioactive isotope of carbon, having six protons and eight neutrons in the nucleus. However, C-14 does not last forever and there will come a time when it loses its extra neutrons and becomes Carbon-12.
5 a) 
→ 
5 b) 
→ 
5 c) 
→ 
(already balanced so don't need to change)
5 d) 
→ 
5 e) 
→ 
EXPLANATION (IF NEEDED):
1. Write out how many atoms of each element is on the left (reactant side) and right (product side) of the arrow.
2. Start multiplying each side accordingly to try to get atoms of the elements on both sides equal.
EXAMPLE OF BALANCING:
Answer:
B
Explanation:
Trust me I've had problems like these
The empirical formula for this vitamin : C₃H₄O₃
<h3>Further explanation
</h3>
The empirical formula is the smallest comparison of atoms of compound =mole ratio of the components
The principle of determining empirical formula
- Determine the mass ratio of the constituent elements of the compound.
- Determine the mole ratio by dividing the percentage by the atomic mass
Mass of C in CO₂ :(MW C = 12 g/mol, CO₂=44 g/mol)
Mass of H in H₂O :(MW H = 1 g/mol, H₂O = 18 g/mol)
Mass O = Mass sample - (mass C + mass H) :
mol ratio C : H : O =
A is the answer
Hope it helps :)
Atomic mass is the quantity of protons that have in a atom. Which atom have different numbers of protons, being able to be identified by them.
