Question

Which of the following has allotropes
A.Aluminium
B.Boron
C.Indium
D.Thallium

Answer 1

To answer this question, you should recall the concept of allotropes. The term allotrope can be defined as one or more physical forms of a chemical element that occurs in the same physical state. These are structural types of the same element and therefore can exhibit differences in physical and chemical properties.

Complete Step by step solution:
Elements are substances that are made from a single type of atom. An element cannot be broken down into any other substance. These act as basic building blocks and everything in the universe is made from these. Examples include carbon, sulfur, oxygen, iron, copper, aluminium. Elements are generally denoted by their symbols. Allotropes are made up of a single element.
The major properties of allotropes include: Allotropes are various structural types of the same element and therefore can exhibit different physical and chemical properties. The allotropic forms change is caused by the same forces that influence other structures, namely light, pressure and temperature. Thus, the stability of the different allotropes relies on specific conditions.
From the options, we know that Boron can be prepared in several crystalline and amorphous forms such as $\alpha$ -rhombohedral, $\beta$ -rhombohedral, and $\beta$-tetragonal.

Thus, the correct answer to this question is option B.

Note: You should know about the most common allotrope i.e. amorphous boron. Amorphous boron contains ${{\text{B}}_{{\text{12}}}}$ regular icosahedra that are randomly bonded to each other without long-range order. Pure amorphous boron can be produced by thermal decomposition of diborane at temperatures below $1000\;{^\circ C}$. Annealing at $1000\;{^\circ C}$ converts amorphous boron to $\beta$ -rhombohedral boron.