The screening effect of inner electrons will lead to 

a. Decrease in the ionization potential.

b. Increase in the ionization potential.

c. Decrease in electron affinity.

d. Increase in electron affinity.

Choose the correct statements for element ${}_9{}^{19}\mathrm{M}.$

a. Formation of ${\mathrm{M}}^{-}$ is an endothermic process.

b. It's anion is isoelectronic with neon.

c. It has the smallest size in its period.

d. It has the highest electron gain enthalpy in its group.

Identify the following statements is true and false.

${\mathrm{S}}_1$: Among ${\mathrm{Li}}^{-}, {\mathrm{Be}}^{-}, {\mathrm{B}}^{-}$ and ${\mathrm{C}}^{-},$ ${\mathrm{Be}}^{-}$ is the least stable ion.

${\mathrm{S}}_2$: If the same element is forming oxides in different oxidation states, then the oxide in which the element shows the highest oxidation state will be highly acidic in nature.

${\mathrm{S}}_3$: Amphiprotic oxide is one which can accept and release ${\mathrm{H}}^{+}$ ions.

${\mathrm{S}}_4$: In alkaline-earth metals, electronegativity values decrease down the group.

Identify the following statements is true and false-

${\mathrm{S}}_1:$ Long-form of the periodic table helps to predict the relative ionic character of the bond between any two elements.

${\mathrm{S}}_2:$ Metallic and covalent radii of potassium are $203 \mathrm{pm}$ and $230 \mathrm{pm}$ respectively.

${\mathrm{S}}_4:$ Formation of ${\mathrm{S}}^{2-}$ and ${\mathrm{Ar}}^{-},$ both require the absorption of energy.

Which of the following statements are true and false?

${\mathrm{S}}_1: {\mathrm{IE}}_1$ of $\mathrm{Sr}>\mathrm{Rb}$ but ${\mathrm{IE}}_2$ for $\mathrm{Rb}>\mathrm{Sr}$.

${\mathrm{S}}_2:$ The ionic radii of ${\mathrm{Li}}^{+}, {\mathrm{K}}^{+}, {\mathrm{Mg}}^{2+}$and ${\mathrm{Al}}^{3+}$ in $\mathrm{Å}$ are $0.76, 1.38, 0.720$ and $0.535,$ respectively.

${\mathrm{S}}_3:$ The negative value of electron gain enthalpy of $\mathrm{Cl}>\mathrm{F}$ because there is weak electron-electron repulsion in a bigger $3\mathrm{p}$ subshell of $\mathrm{Cl}$  as compared to compact $2\mathrm{p}$ subshell of $\mathrm{F}$.

${\mathrm{S}}_4:$ The second ionization energy of copper is less than potassium.