Octane number of natural gas is

The correct answer is (a) 80 – 100.

Octane number is a measure of a fuel’s ability to resist knocking in an internal combustion engine. The higher the octane number, the more resistant the fuel is to knocking. Natural gas has an octane number of 80-100, which means it is a good fuel for use in internal combustion engines.

Option (b) is incorrect because natural gas has an octane number of 80-100, not 80-90.

Option (c) is incorrect because natural gas has an octane number of 80-100, not 90-100.

Option (d) is incorrect because natural gas has an octane number of 80-100, not greater than 100.