Question

0.2% phenol is commonly used as:
(A) an insecticide
(B) an antiseptic
(C) a disinfectant
(D) an anaesthetic

Answer 1

Hint: Think about the definitions of all the options given and what kind of compounds and chemicals are used to carry out the functions. Think carefully about the difference between an antiseptic and a disinfectant.

Complete step by step solution:
We will look at the listed uses one by one to check in which role phenol can be used as.
-Insecticide: We know that insecticides are chemicals that are sprayed on agricultural produce to prevent any infestation of insects from occurring. Phenol is toxic to living organisms but to need to be present in a considerable quantity before it can cause any harm. Spraying high concentrations of phenol on agricultural produce will be counterproductive since it is more likely to kill the plant cell than the insects. So, this is not the correct answer.
-Antiseptic: An antiseptic is usually used on the skin of living beings to prevent infections on wounds or during surgeries. A very low concentration of phenol can be used as it has to be applied to the living tissue directly. A higher concentration will be harmful since it may cause the cells of the living tissue to die too. So, this is the correct answer.
-Disinfectant: A disinfectant is used to prevent the growth of microorganisms on non-living surfaces. The microbes present on these surfaces are usually more resistant and require a stronger concentration of the chemical than an antiseptic. We also don’t have to worry about any living cells so a higher concentration can be used. So, this is not the correct answer.
-Anaesthetic: Phenol cannot be used as an anaesthetic since anaesthetics desensitize neuronal cells. Phenol kills cells, which is not required when anaesthesia has to be given to medical patients. So, this is not the correct answer.

So, the answer to this question is option (B).

Note: Remember that phenol can be used as an anaesthetic as well as a disinfectant due to its ability to kill living cells. A lower concentration of phenol of about 0.2% is used as an antiseptic and a higher concentration of about 1% is used as a disinfectant.