Yet another puzzle sheet !

[Mags22]

Each number is linked to a phrase or fact e.g. 7D in a W = 7 days in a week
Have ideas on some but just checking!
1 ) 9C of H in D I
2)206B in an A H B
3)5V in the A
4)37D C is H B T
5)81S on a S G
Thankyou !

[vegasmad]

3) 5 vowels in the alphabet

[Stephen_G]

2)206B in an A H B = 206m Bones in an Adult Human Body

4)37D C is H B T = 37 Degrees is Human Body Temperature

[johnalex]

5) 81 Squares on a Sudoku Grid