Question

Which of the lead oxide is used as ‘Sindhur’?
(A) $PbO$
(B) $\text {Pb}{{\text{O}} _ {2}} $
(C) $\text{P}{{\text{b}} _ {2}} {{\text{O}} _ {3}} $
(D) $\text{P}{{\text{b}} _ {3}} {{\text{O}} _ {4}} $

Answer 1

Hint: Since all the mentioned options in the above statement are the oxides of the lead and the lead oxide from above which is red in color, used in sindhur and the oxidation state of lead in that compound of lead is 8/3. Identify that.

Complete step by step solution:
-Lead is a metal having the atomic number 82 and lies in the 18th group and belongs to the category of carbon family. It reacts with oxygen forming various oxides of lead i.e. The lead oxide PbO, lead dioxide $\text{Pb}{{\text{O}}_{2}}$, lead trioxide $\text{P}{{\text{b}}_{2}}{{\text{O}}_{3}}$ and triplumbic tetroxide $\text{P}{{\text{b}}_{3}}{{\text{O}}_{4}}$ etc.
-Out of these all oxides of the lead, $\text{P}{{\text{b}}_{3}}{{\text{O}}_{4}}$, is red in colour and it is generally called as lead tetroxide or triplumbic tetraoxide.Due to the red colour of the $\text{P}{{\text{b}}_{3}}{{\text{O}}_{4}}$, it is commonly called as the red oxide of lead. It is chemically formed by the reaction of lead dioxide i.e. $\text {Pb}{{\text{O}} _ {2}} $ and lead oxide i.e. $PbO$. The chemical reaction occurs as:
$\text{4PbO+2Pb} {{\text{O}} _ {2}} \to\text{2P} {{\text{b}} _ {3}} {{\text{O}} _ {4}} $
-Lead trioxide (red colour)
-In this, the mixture of lead dioxide and lead oxide in the ratio 1:1 and therefore also called as Pb (II, IV) oxide.
-Lead tetroxide has a tetragonal in structure at room temperature and is insoluble in water and in ethanol but it is soluble in acids like the hydrochloric acid, acetic acid etc. When heated to a higher temperature i.e. 500°C, it decomposes to lead (II) oxide and oxygen.
$2\text{P}{{\text{b}} _ {3}} {{\text{O}} _ {4}} $ $\rightarrow$ $6 PbO +$ ${{\text{O}} _ {2}} $
-Lead tetra dioxide i.e. Red lead is used as a pigment for paint in case of iron objects. But it is highly toxic in nature and due to this property of lead tetroxide it is used in limited objects. It is used in rubber compounds and it is also used in place of magnesium oxide as it provides better water resistance properties than magnesium oxide. Being red in colour is also used in the sindhur due to its colour characteristics.

Hence, option (D) is correct.

Note: Lead tetroxide is toxic when inhaled and their acclamation in organisms results in lead poisoning and is very fatal for the organisms.