Periodic Trends in the Properties of Elements

The ions  ${\mathrm{O}}^{2-},{\mathrm{F}}^{-},{\mathrm{Na}}^{+},{\mathrm{Mg}}^{2+}\mathrm{and}{\mathrm{Al}}^{3+}$ are isoelectronic. Their ionic radii show:

In the expression of the electronegativity in Allred-Rochow's Scale- $\mathrm{EN}=0.359\frac{\mathrm{Z}}{{\mathrm{r}}^2}+ 0.744$, 

$\mathrm{Z}$ is effective _____ charge, and $\mathrm{r}$ is covalent radius of atom.

How will you express the electronegativity in Allred-Rochow's Scale?

Which element has the maximum value of electronegativity in Allred-Rochow's Scale?

What do you mean by Allred-Rochow's Scale of Electronegativity ?

Assertion. ${\mathrm{Na}}^{+}$ and ${\mathrm{Al}}^{3+}$ are isoelectronic but the magnitude of the ionic radius of ${\mathrm{Al}}^{3+}$ is less than that of ${\mathrm{Na}}^{+}$ .

Reason. The magnitude of effective nuclear charge of the outer shell electrons in ${\mathrm{Al}}^{3+}$ is greater than in ${\mathrm{Na}}^{+}$ .

The boiling point of bromine is_____than chlorine(greater/lower).

The boiling point of phosphorus is greater than nitrogen.

The correct order of boiling point of halogens is
 

The correct order of boiling point of halogens 

The metallic radius is half of the total distance between the nuclei of two adjacent atoms in a _____.

Mark the following statement as true or false.

Metallic radii increases across the period due to an increase in the effective nuclear charge.

How does metallic radius defined?

Arrange $\mathrm{B}\mathrm{e},\mathrm{}\mathrm{M}\mathrm{g},\mathrm{}\mathrm{C}\mathrm{a},\mathrm{}\mathrm{S}\mathrm{r}$ in the ascending order of ionisation enthalpy.

The correct order of $1^{\mathrm{st}}$ ionisation enthalpy among the following elements $\mathrm{Be}, \mathrm{B}, \mathrm{C}, \mathrm{N}, \mathrm{O}$ is