Vanderwaal Radius

Q. To determine the radii of a univalent ion, Pauling gave a method as follows:
i. In an ionic crystal of the type $M^{+}{X}^{-}$, cations and anions are in contact with each other. Therefore, the sum of their ionic radius is equal to the interionic distance.
ii. $r_M^{+}+r_X^{-}=\frac{c}{Z_{eff}\left(M^{+}\right)}+\frac{c}{Z_{eff}\left(X^{-}\right)}pm$ $Z_{eff}$ is the effective nuclear charge $Z_{eff}=Z-\sigma$ ; where $\sigma$ is the screening constant.
For $\text{Ne},\sigma =4.5$
$\therefore r_{\text{M}}^{+}=\frac{c}{Z_{\text{eff}}\left(M^{+}\right)}$ and $r_X^{-}=\frac{C}{Zeff\left(X^{-}\right)}$

In $\text{NaF}$ crystal, $r_{Na}^{+}+r_F^{-}=230$ pm therefore, the radius of $F^{-}$ is

1. 136 pm
2. 94.5 pm
3. 112 pm
4. 115 pm

Q. In the closest packing of atom A of radius r_a, the radius of atom B that can be fitted in tetrahedral void is

1. 0.225

2. 0.155 r_a

3. 0.414 r_a

4. 0.732 r_a

Q.

Magnitude of which of the following property of alkali metals increases with the increase of atomic number

1. Ionic radius

2. Electronegativity

3. First ionization energy

4. Melting point

Q. Which of the following elements has the largest Van der Waals radii?

1. Ne

2. Cl

3. O

4. F

Q. In LiI Crystal, I- ions form a cubical closest packed arrangement and Li+ ions occupy octahedral holes. Calculate the limiting ionic radii of Li+ and I-- if a= 600pm.

1. 65 pm

2. 87.84 pm

3. 12.8 pm

4. 24 pm

Q.

Atomic radic of fluorine and neon in $\mathring{A}$ units are respectively given by

1. 0.72, 160

2. 1.60 , 1.60

3. 0.72, 07.72

4. None of these

Q. Arrange the elements in increasing order of atomic radius Na, Rb, K, Mg.

1. Na < K < Mg < Rb
2. K < Na < Mg < Rb
3. Mg < Na < K < Rb
4. Rb < K < Mg < Na

Q. Why does atomic radius depend on Zeff?

Q. Amongst the elements B, Al, C and Si

1. Al
2. B
3. C
4. Si

Q. Atomic radii of fluorine and neon in Angstrom units are respectively given by:

1. $0.72,1.60$
2. $1.60,1.60$
3. $0.72,0.72$
4. none of these

Q. Name the element which is in
(i) $1^{st}$ group and $3^{rd}$
(ii) $VI{I}^{th}$ group and $2^{nd}$ period.

Q. Which noble gas is most abundant in the atmospheric dry air?

Q. The ratio of radius of first orbit in hydrogen to the radius of first orbit in deuterium will be:

1. 1 : 1
2. 1 : 2
3. 2 : 1
4. 4 : 1

Q. Which of the following elements has the largest Van der Waals radii?

1. $Ne$

2. $Cl$

3. $O$

4. $F$

Q.

Atomic radic of fluorine and neon in $\mathring{A}$ units are respectively given by

1. 0.72, 160

2. 1.60 , 1.60

3. 0.72, 07.72

4. None of these

Q. The elements with atomic numbers $39$ to $48$ belong to:

1. forth period
2. fifth period
3. sixth period
4. third period

Q.

The atomic radius in case of inert gasses is?

1. Ionic radii

2. Coralent radii

3. Vander Waals radii

4. None

Q. Define the correct order of atomic radius.

1. $Na>Mg>Li>Be$
2. $Na>Li>Mg>Be$
3. $K>Rb>Ca>Sr$
4. $Rb>K>Sr>Ca$

Q. Compare atomic radii of the third-period elements while moving from left to right:

1. $Na>Mg>Al>Si>P>S>Cl>>Ar$
2. $Na<Mg<Al<Si<P<S=Cl<<Ar$
3. $Na<Mg<Al<Si<P$
4. none of these

Q. Which of the following has the largest size?

1. $Na$
2. ${Na}^{+}$
3. $Mg$
4. ${Mg}^{+2}$

Q. What is van der waal's radii ?

Q. Pick the wrong statement from the following.
Elements with atomic number $5$ belong to group $15$.

Q. Why ionic radii of br- is greater than s^2- ??

Q. if the radius of Br- ion is 0.182nm how large cation can fit in each tetra hederal hole

Q. The elements with atomic number 10, 18 belong the:

1. same period
2. different periods
3. same group
4. none of these

Q. To determine the radii of a univalent ion, Pauling gave a method as follows:
i. In an ionic crystal of the type $M^{+}{X}^{-}$, cations and anions are in contact with each other. Therefore, the sum of their ionic radius is equal to the interionic distance.
ii. $r_M^{+}+r_X^{-}=\frac{c}{Z_{eff}\left(M^{+}\right)}+\frac{c}{Z_{eff}\left(X^{-}\right)}pm$ $Z_{eff}$ is the effective nuclear charge $Z_{eff}=Z-\sigma$ ; where $\sigma$ is the screening constant.
For $\text{Ne},\sigma =4.5$
$\therefore r_{\text{M}}^{+}=\frac{c}{Z_{\text{eff}}\left(M^{+}\right)}$ and $r_X^{-}=\frac{C}{Zeff\left(X^{-}\right)}$

In $\text{NaF}$ crystal, $r_{Na}^{+}+r_F^{-}=230$ pm therefore, the radius of $F^{-}$ is

1. 136 pm
2. 94.5 pm
3. 112 pm
4. 115 pm