Updated By SaraNextGen

On April 21, 2024, 11:35 AM

Question 3.35:

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

Question 3.36:

The size of isoelectronic species — F^–, Ne and Na⁺ 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 F^–, Ne, and Na⁺ is as follows:

F^– < Ne < Na⁺

Z     9     10     11

Therefore, the order of the increasing size of F^–, Ne and Na⁺ is as follows:

Na⁺ < Ne < F^–

Question 3.37:

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 n value are more attracted to the nucleus than electrons in orbitals bearing a higher n 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 n value.

Question 3.38:

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

(a) B > Al > Mg > K           (b) Al > Mg > B > K

(c) Mg > Al > K > B           (d) K > Mg > Al > B

Answer:

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

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

Considering the above statements, we get K > Mg.

Hence, the correct order of metallic character is K > Mg > Al > B.

Question 3.39:

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

(a) B > C > Si > N > F            b) Si > C > B > N > F

(c) F > N > C > B > Si            d) F > N > C > Si > B

Answer:

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

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

Hence, the correct order of their non-metallic characters is F > N > C > B > Si.

Question 3.40:

Considering the elements F, Cl, O and N, the correct order of their chemical reactivity in terms of oxidizing property is:

(a) F > Cl > O > N           (b) F > O > Cl > N

(c) Cl > F > O > N           (d) O > F > N > Cl

Answer:

The oxidizing character of elements increases from left to right across a period. Thus, we get the decreasing order of oxidizing property as F > O > N.

Again, the oxidizing character of elements decreases down a group. Thus, we get F > Cl.

However, the oxidizing character of O is more than that of Cl i.e., O > Cl.

Hence, the correct order of chemical reactivity of F, Cl, O, and N in terms of their oxidizing property is F > O > Cl > N.