Question

Find the odd one out:
Thermos flask, igloos, icebox, candle
(A) Candle
(B) Icebox
(C) Thermos flask
(D) Igloo

Answer 1

Hint In the question, we are given 4 objects. 3 out of these 4 objects are used for insulating the heat. i.e. they are used to keep the inner surroundings cool. The 4th one is used for the production of heat. It does not hold the heat inside but instead exhibits to the surroundings.

Complete Step by step solution
To find the odd one out, let us look at what all these items are and what their purpose is.
A thermos flask is a special kind of storage flask/ bottle in which a hot substance such as tea or milk remains hot and a cold substance such as ice remains cold for a long period of time. Basically, a thermos flask acts as an insulator which doesn’t allow heat energy to get absorbed from the surroundings or escape from inside of the flask.
An icebox is a compact box specifically used to keep cold substances such as ice or food to keep them cold for long periods of time to prevent ice from melting, food from spoiling, etc. An icebox is also a heat insulator which doesn’t allow heat from the surroundings to conduct through it and reach inside of the box.
An igloo is a house/ hut built out of snow usually in colder regions, the snow acts as a heat insulator and the insides of the igloo remain warm.
A candle is generally made of wax, in which there is a flammable wick embedded in it. Once the wick is ignited, it starts emitting heat and light energy (and sometimes, fragrance).
All the options work on the principle of heat insulation except a candle.

Therefore, option (A) is correct.

Note Ice Boxes are sometimes confused with freezers and refrigerators. However, both are used to keep their contents cooler than the surroundings but the working principles of both are very different. An icebox works on heat insulation whereas a refrigerator works as a reverse heat engine.