Ionic Sizes of Actinides

Q. The spin only magnetic moments (in $BM)$ for free $T{i}^{3+},V^{2+}andS{c}^{3+}$ ions respectively are

$(At.No-Sc:21,Ti:22,V:23)$

1. $1.73,0,3.87$
2. $3.87,1.73,0$
3. $0,3,87,1.73$
4. $1.73,3.87,0$

Q. Which of the following lanthanoid ions is diamagnetic ?
(Atoms, Ce = 58, Sm = 62, Yb = 70)

1. $Y{b}^{2+}$
2. $E{u}^{2+}$
3. $C{e}^{2+}$
4. $S{m}^{2+}$

Q. Why is the Ionisation enthalpy of hydrogen higher than that of sodium?

Q. The electronic configuration of the outermost shell of the most electronegative element is

1. $5s^{2}5p^5$
2. $2s^{2}2p^5$
3. $3s^{2}3p^5$
4. $4s^{2}4p^5$

Q. Magnetic moment of $[MnC{l}_4{]}^{2-}is5.92B.M$. Explain giving reason.

Q. Give reason:

Q. Magnetic moment of $[MnC{l}_4{]}^{2-}is5.92B.M$. Explain giving reason.

Q. 17. Lanthanoid contraction and actinoid contraction

Q.

Arrange $\mathrm{S},\mathrm{O}$ and $\mathrm{Se}$ in ascending order of electron affinity.

1. $\mathrm{Se}<\mathrm{S}<\mathrm{O}$

2. $\mathrm{Se}<\mathrm{O}<\mathrm{S}$

3. $\mathrm{S}<\mathrm{O}<\mathrm{Se}$

4. $\mathrm{S}<\mathrm{Se}<\mathrm{O}$

Q. Actinoid contraction is more than lanthanoid contraction because:

1. energy of 4f and 5f orbitals are same
2. 5f orbitals are more diffused as compared to 4f orbitals
3. actinoids show greater range of oxidation states than lanthanoids
4. actinoids are highly reactive

Q. Account for: Actinoids show irregularities in their electronic configurations.

Q. There is a gradual decrease in size of atoms or $M^{+3}$ ions across the actinide series

1. True
2. False

Q.

Which of the following statement is true?

1. Actinoid contraction is equally same as lanthanoid contraction

2. Actinoid contraction is smaller than lanthanoid contraction.

3. There is no actinoid contraction observed.

4. Actinoid contraction is greater than lanthanoid contraction

Q. The actinide contraction is due to:

1. perfect shielding of $5f$ election
2. imperfect shielding of $4f$ election
3. imperfect shielding of $5f$ electron
4. perfect shielding of $4f$ election

Q. Which of the following pairs has the same size?

1. $F{e}^{2+},Z{n}^{2+}$
2. $Z{r}^{4+},H{f}^{4+}$
3. $Z{n}^{4+},H{f}^{4+}$
4. $Z{r}^{4+},T{i}^{4+}$

Q. Element ${}^{\prime }{X}^{\prime }$ is having atomic number $28,$ it gives two electrons to element ${}^{\prime }{Y}^{\prime }.$
Write down the characteristics of that block

Q. There is a gradual decrease in size of atoms or $M^{+3}$ ions across the actinide series

1. True
2. False

Q. Assign reasons for the following:
From element to element the actinoid contraction is greater than the lanthanoid contraction.

Q. How would you account for the following:
(i) Among lanthanoids, Ln (III) compounds are predominant. However, occasionally in solution or in
solid compounds, +2 and +4 ions are also obtained.
(ii) The $E_{M^{2+}/M}^o$ for copper is positive (0.34 V). Copper is the only metal in the first series of transition elements showing this behavior.
(iii) The metallic radii of the third (5d) series of transition metal are nearly the same as those of the corresponding members of the second series.