The cause of the diagonal relationship is:

The element with a very high ionization enthalpy but zero electron gain enthalpy is ....

In which of the following sets,elements are not correctly arranged with the property shown in brackets?

Consider the following values of $IE$ $(eV)$ for elements $W$ and $X$:

Element	$IE_1$	$IE_2$	$IE_3$	$IE_4$
$W$	$10.5$	$15.5$	$24.9$	$79.8$
$X$	$8$	$14.8$	$78.9$	$105.8$

Other two elements $Y$ and $Z$ have outer electronic configuration $ns^2 np^4$ and $ns^2 np^5$ respectively. According to the given information,which of the following compound$(s)$ is/are not possible?
$(a) W_2Y_3, (b) X_2Y_3, (c) WZ_2, (d) XZ_2$

How many of the following statements are correct?
$(a)$ 'He' is the second most abundant element in the universe.
$(b)$ The symbol for the element with atomic number $110$ is Ds.
$(c)$ Osmium has the highest density among all elements.
$(d)$ Francium is the most electropositive element in the periodic table.

The first ionization energy for $Li$ is $5.4 \ eV$ and electron affinity of $Cl$ is $3.61 \ eV$. The $\Delta H$ (in $kJ/mol$) for the reaction $Li_{(g)} + Cl_{(g)} \to Li^{+}_{(g)} + Cl^{-}_{(g)}$ is (if resulting ions do not combine with each other) ($1 \ eV = 1.6 \times 10^{-19} \ J$,$N_A = 6.022 \times 10^{23} \ mol^{-1}$)