Question

1. a mixture of petrol and diesel is separeated at lower temperature .why

2. why kerosene called a hydrocarbon

Answer 1

1) When crude oil undergoes fractional distillation, petrol which has a B.P of around 60 ⁰C will separate out first and then Diesel which boils at around 250 ⁰C.
This occurs because petrol contains molecules with carbon chain around 5-7 whereas diesel has an avg. of 14 carbons.

2) Kerosene contains paraffins i.e alkanes whose carbon chain ranges from C6 to C16 as they contain only C&H they are called hydrocarbons.