Chemistry Class 11 NCERT Solutions: Chapter 3 Classification of Elements and Periodicity Part 6

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Q: 34. Which of the following statements related to the modern periodic table is incorrect?

(A) The p-block has columns, because a maximum of electrons can occupy all the orbitals in a p-shell.

(B) The d-block has 8 columns, because a maximum of electrons can occupy all the orbitals in a d-subshell.

(C) Each block contains a number of columns equal to the number of electrons that can occupy that subshell.

(D) The block indicates value of azimuthal quantum number (I) for the last subshell that received electrons in building up the electronic configuration.

Answer:

The d-block has 10 columns because a maximum of 10 electrons can occupy all the orbitals in a d subshell.

Thus, statement (b) is incorrect.

Q: 35. Anything that influences the valence electrons will affect the chemistry of the element. Which one of the following factors does not affect the valence shell?

(A) Valence principal quantum number (n)

(B) Nuclear charge (Z)

(C) Nuclear mass

(D) Number of core electrons

Answer:

Nuclear mass does not affect the valence electrons because the nuclear mass is so small, it is considered as negligible. Thus, option (c) is the correct answer.

Q: 36. The size of isoelectronic species is affected by

(A) Nuclear charge (Z)

(B) Valence principal quantum number (n)

(C) Electron-electron interaction in the outer orbitals

(D) None of the factors because their size is the same

Answer:

The size of an isoelectronic species increases with a decrease in the nuclear charge (Z). For example, the order of the increasing nuclear charge of is as follows:

Therefore, the order of the increasing size of is as follows:

Q: 37. Which one of the following statements is incorrect in relation to ionization enthalpy?

(A) Ionization enthalpy increases for each successive electron.

(B) The greatest increase in ionization enthalpy is experienced on removal of electron from core noble gas configuration.

(C) End of valence electrons is marked by a big jump in ionization enthalpy.

(D) Removal of electron from orbitals bearing lower n value is easier than from orbital having higher n value.

Answer:

Electrons in orbitals bearing a lower value are more attracted to the nucleus than electrons in orbitals bearing a higher value. Hence, the removal of electrons from orbitals bearing a higher n value is easier than the removal of electrons from orbitals having a lower value.

Q: 38. Considering the elements B, Al, Mg, and K, the correct order of their metallic character is:

(A)

(B)

(C)

(D)

Answer:

The metallic character of elements decreases from left to right across a period. Thus, the metallic character of is more than that of .

The metallic character of elements increases down a group. Thus, the metallic character of is more than that of .

Considering the above statements, we get

Hence, the correct order of metallic character is

Q: 39. Considering the elements B, C, N, F, and Si, the correct order of their non-metallic character is:

(A)

(B)

(C)

(D)

Answer:

The non-metallic character of elements increases from left to right across a period. Thus, the decreasing order of non-metallic character is

Again, the non-metallic character of elements decreases down a group. Thus, the decreasing order of non-metallic characters of and are . However, Si is less non-metallic than B i.e.

Hence, the correct order of their non-metallic characters is .