Which of the following class of organic compound does not contain (C = O) group in some form ?

(1) Aldehydes
(2) Ethers
(3) Carboxylic acids
(4) Esters

Which of the following hydrocarbons have acidic hydrogen?
(1) CH₂=CH₂
(2)
(3) CH₄
(4) C₆H₆

Coal is called fossil fuel because :

(1) In future coal will become completely exhausted
(2) It was formed 300 million years ago
(3) Fossils are obtained along with mining of coal
(4) It was formed from the dead remains of living organisms

Hydrocarbon 2-methylbutane is an isomer of

(1) n-pentane
(2) n-butane
(3) propane
(4) iso-butanens.

An organic compound which is used to preserve biological specimen is 

(1) ether 
(2) methanal 
(3) ethanal 
(4) ethanol