Question

Q.6
Which of the following are isomers -
(1) Ethanol and ethoxy ethane
(2) Methanol and methoxy methane
(3) Propanoic acid and ethyl acetate
(4) Propionaldehyde and acetone
​

Answer 1

Answer:

first and third ans is correct

Answer 2

Answer:

The correct answer is option 4

Explanation:

For identifying isomers between a pair of compounds, the molecular masses of both the compounds can be compared.

• Ethanol with chemical formula C2H5OH consists of two carbon atoms of mass 12 gram each and six hydrogen atoms of 1 gram each and one oxygen atom of 16 grams. Therefore, the molecular mass of Ethanol is $(2)(12)+(6)(1)+16=46 grams$
• Hence, the molecular mass of Ethanol is 46 grams.

• Now, Ethoxy ethane with chemical formula C2H5OC2H5 consists of four carbon atom of 12 grams each along with ten hydrogen atom of 1 gram each and one oxygen atom of 16 grams. Therefore, the molecular mass of Ethoxy ethane is $(4)(12)+(10)(1)+16=74 grams$
• Hence, the molecular mass of Ethoxy ethane is 74 grams.
• Since, the molecular mass of Ethanol and Ethoxy ethane are not same. Therefore, Ethanol and Ethoxy ethane are not isomers.
• Methanol with chemical formula CH3OH consists of one carbon atom of 12 grams along with four hydrogen atom of 1 gram each and one oxygen atom of 16 grams. Therefore, the molecular mass of Methanol is $(1)(12)+(4)(1)+16=32 grams$
• Hence, the molecular mass of Methanol is 32 grams.
• Now, Methoxy methane with chemical formula CH3OCH3 consists of two carbon atom of 12 grams each along with six hydrogen atom of 1 gram each and one oxygen atom of 16 grams. Therefore, the molecular mass of Methoxy methane is$(2)(12)+(4)(1)+16=46 grams$
• Hence, the molecular mass of Methoxy methane is 46 grams.
• Since, the molecular mass of Methanol and Methoxy methane are not same. Therefore, Methanol and Methoxy methane are not isomers.
• Propionic acid with chemical formula CH3CH2COOH consists of three carbon atom of 12 grams each along with six hydrogen atom of 1 gram each and two oxygen atom of 16 grams. Therefore, the molecular mass of Propionic acid is$(3)(12)+(6)(1)+(2)(16)=74 grams.$
• Hence, the molecular mass of Propionic acid is 74 grams.
• Now, Ethyl acetate with chemical formula CH3COOC2H5 consists of four carbon atom of 12 grams each along with eight hydrogen atom of 1 gram each and two oxygen atom of 16 grams. Therefore, the molecular mass of Ethyl acetate is
• $(4)(12)+(8)(1)+(2)(16)=88 grams$
• Hence, the molecular mass of Ethyl acetate is 88 grams.
• Since, the molecular mass of Propionic acid and Ethyl acetate are not same. Therefore, Propionic acid and Ethyl acetate are not isomers.
• Propanal with chemical formula CH3CH2CHO consists of three carbon atom of 12 grams each along with six hydrogen atom of 1 gram each and one oxygen atom of 16 grams. Therefore, the molecular mass of Propanal is $(3)(12)+(6)(1)+16=58 grams$

• Hence, the molecular mass of Propanal is 58 grams.
• Now, Acetone with chemical formula CH3COCH3
• consists of three carbon atom of 12 grams each along with six hydrogen atom of 1 gram each and one oxygen atom of 16 grams. Therefore, the molecular mass of Ethoxy ethane is$(3)(12)+(6)(1)+16=58 grams.$
• Hence, the molecular mass of Acetone is 58 grams.
• Since, the molecular mass of Propanal and Acetone are same. Therefore, Propanal and Acetone are isomers.
• So the correct answer is option (4).