Question

Which is the least conductor of heat?
a.) Gold
b.) Platinum
c.) Silver
d.) Lead

Answer 1

Hint: It is a heavy metal that is denser than most common materials. It is soft and malleable, and also has a relatively low melting point. When freshly cut, it is silvery with a hint of blue; it tarnishes to a dull gray color when exposed to air.

Complete step by step answer:
- It is a heavy metal and has a low melting point. Lead is a chemical element with symbol Pb and having an atomic number 82. As we know, metal oxides are poor conductors of heat and electricity, the reason behind lead being a poor conductor of heat is because it readily reacts with the atmosphere to form lead oxide.
- Generally, for any metals to be a good conductor of heat it should have many free electrons which will transfer heat by bumping against each other. Few metals are poor conductors of heat ,due to less concentration of free electrons. Silver is the best conductor of heat , copper and aluminium are good conductors while mercury is a poor conductor and lead is the poorest conductor.
- Lead is used for soldering alloys because of it's acceptable conductivity for joints, low melting point and good adhesion with other conductors like copper or zinc under those low soldering temperatures.
Therefore, Lead is the least conductor of heat.
So, the correct answer is “Option D”.

Note: It causes almost 10 % of intellectual disability. It can result in behavioural problems. Some of these effects are permanent. Exposure to lead can occur by contaminated air, water or consumer products.