Question 1

1. Group:6

   Period: 2

2. n=m/Mr

   Mr=202g

   n=75/202

   n= 0.37 mol

3. Transition metals

Question 2

1. Endothermic
2. Reversible
3. CuI
4. brown, green, brown
5. carboxylic acid

Question 3

1. It can last for longer now.

2. Fe2O3

3. O: Iron

   R: Oxygen

4. 36, 46

   36, 48

5. Noble gases have a complete outer shell which makes them stable and they do not react.

6. 2,6

7. Covalent bonding occurs between oxygen molecules with two non metals.

8. Exosphere because it has the greatest temperature.

9. Thermosphere because it has the most oxygen.