Question

Number of 1°, 2° and 3° hydrogens in isooctane is:

• A. 9,8,1
• B. 12,5,1
• C. 15,2,1
• D. None of these

Answer 1

The correct option is C 15,2,1

1°, 2°, and 3° hydrogens are the hydrogen atoms bonded to 1°, 2°, and 3° carbon atoms respectively. Primary Carbon (1°) – Carbon attached to one other carbon. Secondary Carbon (2°) – Carbon attached to two other carbons. Tertiary Carbon (3°) – Carbon attached to three other carbons.
Here, the structure of isooctane (2,2,4-trimethylpentane) is,

Thus, No. of 1° H = 15
No. of 2° H = 2
No. of 3° H = 1