Atomic and Ionic Sizes of Lanthanides

Q. Because of lanthanoid contraction, which of the following pairs of elements have nearly same atomic radii? (Numbers in the parenthesis are atomic numbers)

1. Zr(40) and Hf(72)
2. Zr(40) and Ta(73)
3. Ti(22) and Zr(40)
4. Zr(40) and Nb (41)

Q. Lanthanide contraction is due to an increase in:

1. Shielding by 4f electrons
2. Atomic number
3. Effective nuclear charge
4. Size of 4f orbitals

Q. Arrange $C{e}^{+3},L{a}^{+3},P{m}^{+3}$ and $Y{b}^{+3}$ in increasing order of their ionic radii

1. $Y{b}^{+3}<P{m}^{+3}<C{e}^{+3}<L{a}^{+3}$
2. $C{e}^{+3}<Y{b}^{+3}<P{m}^{+3}<L{a}^{+3}$
3. $Y{b}^{+3}<P{m}^{+3}<L{a}^{+3}<C{e}^{+3}$
4. $P{m}^{+3}<L{a}^{+3}<C{e}^{+3}<Y{b}^{+3}$

Q.

Choose incorrect option:-
1. Transition elements exhibit higher enthalpies of atomization.
2. Zinc is a transition element
3. Melting and boiling points increases steadily from Sc to Cu.

1. 1 & 2

2. 2 & 3

3. 1, 2 & 3

4. 3 only.

Q.

Arrange the following atomic numbers in the decreasing order of ease of formation of ionic compounds with a metal ‘M’.

(A) 8

(B) 7

(C) 17

(D) 9

1. DBAC

2. CABD

3. CDAB

4. CBDA

Q. Reason of lanthanoid contraction is

1. Neglibible screening effect of ‘f’ - orbitals
2. Increasing nuclear charge
3. Decreasing nuclear charge
4. Decreasing screening effect

Q. Gradual decrease in atomic and ionic radii from $C{e}^{3+}$ to $L{u}^{3+}$ is called

1. Actinide contraction
2. Lanthanide contraction
3. Both (A) and (B)
4. None of these

Q. Which of the following statement is true with respect to 3d series?

1. Atomic radii gradually decreases from Sc to Zn.
2. Most of these elements have very similar atomic radii. There is hardly any appreciable variation.
3. Atomic radii gradually decreases from Sc to Cr.
4. Atomic radii gradually increases from Sc to Cr.