Question

Which two compounds have the same molecular formula but different chemical and physical properties?

(1) CH3CH2Cl and CH3CH2Br
(2) CH3CHCH2 and CH3CH2CH3
(3) CH3CHO and CH3COCH3
(4) CH3CH2OH and CH3OCH3

Answer 1

The answer is (4) CH3CH2OH and CH3OCH3. You need to figure out which pair has the same molecular formula which means that they have the same number of same atoms. Then you can get the write answer.

Answer 2

Answer is (4) - CH₃CH₂OH and CH₃OCH₃.

Both CH₃CH₂OH and CH₃OCH₃ have same molecular formula as C₂H₆O. But CH₃CH₂OH is an alcohol and CH₃OCH₃ is an ether.

Although two compounds have a same molecular formula, the atomic arrangement of those compounds differs from each other.

Hence, CH₃CH₂OH and CH₃OCH₃ are isomers of the formula C₂H₆O.

Due to the different arrangement of atoms, both compounds have different chemical and physical properties.