Answer
The period and group number for the given elements:
a) Oxygen
Period number: 2
Group number: 6A (or 16)
b) Calcium
Period number: 4
Group number: 2A (or 2)
c) Phosphorus
Period number: 3
Group number: 5A (or 15)
d) Platinum
Period number: 6
Group number: 8B (or 10)
e) Iodine
Period number: 5
Group number: 7A (or 17)
