The second level has s and p orbitals, the s orbital holds two electrons and all three p orbitals also hold two each for a total of eight electrons in the second energy level.
The very last option is the correct answer.
Answer:
2,2,4-trimethylpentane has the higher heat of combustion in kcal/mol.
Explanation:
Heat of combustion is defined as heat evolved on combustion of 1 mole of a substance.
2,2,4-trimethylpentane has the higher heat of combustion in kcal/mol.
Heat combustion of 2,2,4-trimethylpentane = (1304 kcal/mol) and

1 mole of 2,2,4-trimethylpentane on combustion gives 8 mole sof carbon dioxide gas and 9 moles of water.
Heat combustion of ethanol = (327 kcal/mol)

1 mole of ethanol on combustion gives 2 moles of carbon dioxide gas and 3 mole of water.
Heat combustion of ethanol < Heat combustion of 2,2,4-trimethylpentane
I'm not suree.. is his science?