Effect of Nuclear Charge

Q.

Which one of the following is the smallest cation?

1. $N{a}^{+}$

2. $M{g}^{2+}$

3. $C{a}^{2+}$

4. $A{l}^{3+}$

Q. Identify the wrong statement in the following. [CBSE AIPMT 2012]

1. Amongst isoelectronic species, smaller the positive charge on the cation, smaller is the ionic radius
2. Amongst isoelectronic species, greater the negative charge on the anion, larger is the ionic radius
3. Atomic radius of the elements increases as one moves down the first group of the periodic table
4. Atomic radius of the elements decreases as one moves across from left to right in the 2nd period of the periodic table

Q.

Which of the following orders of ionic radii is correctly represented?

1. $H^{-}>H^{+}>H$

2. $N{a}^{+}>F^{-}>O^{2-}$

3. $O^{2-}>F^{-}>N{a}^{+}$

4. $A{l}^{3+}>M{g}^{2+}>N^{3-}$

Q.

The correct order of the decreasing ionic radii among the following isoelectronic species is [CBSE A1PMT 2010]

1. $C{a}^{2+}>K^{+}>S^{2-}>C{l}^{-}$

2. $C{l}^{-}>S^{2-}>C{a}^2+>K^{+}$

3. $S^{2-}>C{l}^{-}>K^{+}>C{a}^{2+}$

4. $K^{+}>C{a}^{2+}>C{l}^{-}>S^{2-}$

Q. As per Pauling, the radius of an isoelectronic ion in a given crystal is inversely proportional to the effective nuclear charge, $Z^{\ast }$.
$Z^{\ast }=Z-\sigma$; where $\sigma$ represents the screening constant. The crystal structure of $\text{NaF}$ is shown as below :

The radius of $F^{-}$ in pm is $(130+x)$ . The value of $x$ in nearest possible integer is

Q. The size of the isoelectronic species $C{l}^{-}$, $Ar$ and $C{a}^{2+}$ is affected by:

1. Principal quantum number of the valence shell
2. Azimuthal quantum number of the valence shell
3. Electron-electron interaction in the outer orbitals
4. Nuclear charge