Question

Which of these is/are transition metals?

Atomic numbers of X, Y, and Z are 30, 40, and 50 respectively.

• A. ‘X’ only
• B. ‘X’ and ‘Z’
• C. ‘X’ and ‘Y’
• D. ‘Y’ and ‘Z’

Answer 1

The correct option is C

‘X’ and ‘Y’

The explanation for the correct option:

Elements of having d orbitals in their outermost or valence shells are transition metals.

Writing the electronic configuration for the elements X, Y, and Z.

• X (30): 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰
• X (30): [Ar] 3d¹⁰ 4s²
• So, the valence shell is 3d.

• Y (40): 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰ 4p⁶5s²4d²
• Y (40): [Kr]4d²5s²
• So, the valence shell is 4d.

• Z (50): 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰ 4p⁶5s²4d¹⁰5p²
• Z (50): [Kr] 4d¹⁰5s²5p²
• So, the valence shell is 5p.

So, according to the electronic configuration, X and Y have valence shell d orbitals. Hence they are transition metals.

The explanation for the incorrect option:

• In the case of element Z, removal of the electron will take part from s and p orbitals.
• It has completely filled ‘d’ orbital. Hence, no electrons will be removed from the d orbital.
• So it is not a transition metal.

Thus, Option ‘C’ is correct.

‘X’ and ‘Y’ are transition metals.