Question

Give IUPAC names and structural formulas of the following:
Neopentane, Isobutane, Formaldehyde, n-Butane, Benzyl chloride, TNT

Answer 1

The IUPAC name of butane is just 'butane' it has formula CH3CH2CH2CH3 (the 2s and 3s should be subscript).

Even the Isobutane is an isomer of butane which has the IUPAC name 'methyl propane' it has formula CH3CH(CH3)CH3. in general 'meth-' means a 1 carbon chain,  as well as 'prop-' means a 3 carbon chain and 'but-' means a 4 carbon chain.