Question

The tailing of mercury on exposure to air shows a change in oxidation number by one.
If true enter 1, else enter 0.
A.) 1
B.) 0

Answer 1

Hint: Try to recall that when ozone is passed through mercury, it loses its meniscus and sticks to the glass due to the formation of mercurous oxide. This is called tailing of mercury. Now, by using this you can easily answer whether the given statement is true or false.

Complete step by step solution:
It is known to you that tailing of mercury is when the mercury (Hg) sticks to the sides of a test tube.
When ozone is passed through mercury, it loses its meniscus and sticks to the glass due to the formation of mercurous oxide. This phenomenon is called tailing of mercury.
So, mercury when starts moving on a surface it leaves a tail and this is what tailing of mercury is called.
This happens because ozone is an oxidizing agent, so when ozone is passed through mercury, ozone oxidizes mercury to mercurous oxide and changes the oxidation state of mercury from 0 to 1. The reaction is:
$2Hg + {O_3} \to H{g_2}O + {O_2}$

Due to this phenomenon, mercury loses its meniscus and starts sticking to the glass. This effect can be removed by washing with water as mercurous oxide is soluble in water.
Therefore, from above we can conclude that the given statement is true. So, option A is the correct option.

Note: It should be remembered to you that when mercury bonds with oxygen, it creates mercurous oxide and this causes it to lose its meniscus.
Also, you should remember that one of the reasons for this effect is that mercury atoms have weak interatomic cohesive forces.