Question

Choose incorrect order regarding property given in the bracket.
4s < 4p (energy in hydrogen atom)
5p > 5d (number of degenerate orbitals)
3dxy > 4dxy (penetration power)
3s > 4s (number of nodal planes)

Answer 1

Answer:

number of degenerate orbitals in 5d>5p

Answer 2

Proper Question: Choose the incorrect order regarding the property given in the bracket:

(a) 4s < 4p (energy in hydrogen atom)

(b) 5p > 5d (number of degenerate orbitals)

(c) 3dxy > 4dxy (penetration power)

(d) 3s > 4s (number of nodal planes)

→ The incorrect orders are: (a) 5p > 5d (number of degenerate orbitals) and (d) 3s > 4s (number of nodal planes).

→ Checking the first option: 4s < 4p (energy in hydrogen atom)

In the case of the hydrogen atom, the energies of the sub-shells 4s, 4p, 4d and 4f follow the following order: 4f > 4d > 4p > 4s. The energy of the sub-shells increases with the increase in the value of the azimuthal quantum number (l).

Therefore the energy of 4p is greater than that of 4s in the hydrogen atom.

• Hence the given statement is correct.

→ Checking the second option: 5p > 5d (number of degenerate orbitals)

We can calculate the number of degenerate orbitals in a subshell by using the formula (2l + 1). Here 'l' is the azimuthal quantum number of the given subshell.

Therefore the number of degenerate orbitals in the 5p subshell would be 3 and the number of degenerate orbitals in the 5d subshell would be 5.

Therefore the number of degenerate orbitals in 5p is lesser than the number of degenerate orbitals in the 5d subshell.

• Hence the given statement is incorrect.

→ Checking the third option: 3dxy > 4dxy (penetration power)

The penetration power depends upon the principal quantum number (n) as well as the azimuthal quantum number (l). The overall quantum number is given as:

1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s < 4f < 5d < 6p < 7s < 5f < 6d < 7p

The penetration power of '3d' orbitals is greater than the penetration power of '4d' orbitals.

Therefore the penetration power of the 3dxy orbital would be greater than the penetration power of 4dxy orbitals.

• Hence the given statement is correct.

→ Checking the fourth option: 3s > 4s (number of nodal planes)

The '3s' and '4s' subshells both are spherical in shape and therefore the number of nodal planes in the '3s', as well as the '4s' subshell, would be equal to zero.

• Hence the given statement is incorrect.

Therefore the incorrect orders are: (a) 5p > 5d (number of degenerate orbitals) and (d) 3s > 4s (number of nodal planes).

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