COMEDK20269 May 2026Morning ShiftChemistryd and f Block ElementsActual
The statements given below contain an assertion and reason. Choose the correct option. Assertion (A) : Cr, Mo and W possess very high melting points in their respective series of elements. Reason (R) : Cr, Mo and W have a large number of unpaired electrons, resulting in strong metallic bonding.
Options
- ABoth A and R are true but R is not the correct explanation of A
- BBoth A and R are true, R is the correct explanation of A
- CA is false but R is true
- DA is true but R is false
Correct answer
B. Both A and R are true, R is the correct explanation of A
Step-by-step solution
The melting points of transition metals depend on the strength of their metallic bonds. The strength of metallic bonding is directly proportional to the number of unpaired electrons in the (n-1)d and ns subshells that can participate in the bonding. Group 6 elements, Chromium (Cr), Molybdenum (Mo), and Tungsten (W), have a maximum or near-maximum number of unpaired electrons in their respective transition series. For example, Cr has the electronic configuration [Ar] 3d⁵ 4s¹ , yielding six unpaired electrons. This l