Transition metals readily form alloys with one another, many of which are homogeneous solid solutions. Which of the following is the main reason for this?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Their atoms have similar metallic radii, within about 15 percent of each other.
In a homogeneous solid solution the atoms of one metal are spread at random among the atoms of the other, in the same crystal lattice.
One atom can take the place of another only when the two are of nearly the same size, with metallic radii within about 15 percent of each other.
The radii of the transition metals are close to one another, so these metals mix readily to form alloys.
Why the other options are incorrect
Option (1) Their atoms have high enthalpies of atomisation, so the metallic bonding is strong. — Incorrect.
A high enthalpy of atomisation shows strong bonding between the atoms of one metal and goes with high melting points.
It does not decide whether the atoms of two metals can replace each other in one lattice.
Option (3) They show variable oxidation states that differ from each other by one unit. — Incorrect. Variable oxidation states matter in the compounds of these metals and in their catalytic action. In an alloy the metals are mixed as atoms, so oxidation states play no part in alloy formation.
Option (4) Small atoms like H, C or N can be trapped inside their crystal lattices. — Incorrect. Trapping small non-metal atoms gives interstitial compounds such as TiC and Mn4N, not alloys of two metals.
NCERT (2026-27 edition):
4.3.14 Alloy Formation – “An alloy is a blend of metals prepared by mixing the components. Alloys may be homogeneous solid solutions in which the atoms of one metal are distributed randomly among the atoms of the other. Such alloys are formed by atoms with metallic radii that are within about 15 percent of each other. Because of similar radii and other characteristics of transition metals, alloys are readily formed by these metals.”