There is a structure of CH3CHCH2CH2CH3, with a –CH3 group attached to the second (from left to right) carbon. Spell out the full name of the compound

Explanation:

2-methyl pentane

At first, we need to select a long chain.

Then, we should number that chain (Numbering will start from that side from which attachment is closer)

Then, For IUPAC name, at first we write the position at which substituent is attached then, name of subsitent and finally the chain name and suffix.

Here,

position of substituent = 2

name of substituent = -methyl

chain name = pent

suffix = -ane

Then,

IUPAC name is 2-methyl pentane

your answer is a. the enthalpy of formation for a pure element in its standard state is always positive.