## The s-Block Elements Questions and Answers Part-9

1. The oxidation state shown by alkaline earth metals is
a) +2
b) +1, +2
c) –2
d) –1, –2

Explanation: The oxidation state shown by alkaline earth metals is +2

2. Which of the following ions has the largest ionic radius?
a) $Be^{2+}$
b) $Mg^{2+}$
c) $Ca^{2+}$
d) $Sr^{2+}$

Explanation: $Sr^{2+}$

3. Density is lowest for
a) Mg
b) Ca
c) Sr
d) Ba

Explanation: Ca contains vacant 3d orbitals which leads much increase in atomic volume of the element hence has the lowest density

4. The first ionization energies of alkaline earth metals are higher than those of the alkali metals. This is because
a) there is an increase in the nuclear charge of the alkaline earth metals
b) there is a decrease in the nuclear charge of the alkaline earth metals
c) there is no change in the nuclear charge
d) None of these

Explanation: there is an increase in the nuclear charge of the alkaline earth metals

5. The first ionization potential of Mg is
a) less than Al
b) more than Al
c) equal to Al
d) can be less or more than Al

Explanation: Mg has more IE1 than Al since the electron has to be removed from completely filled s-valence shell of Mg.

6. The first ionization potentials (eV) of Be and B respectively are
a) 8.29, 9.32
b) 9.32, 9.32
c) 8.29, 8.29
d) 9.32, 8.29

Explanation: 9.32, 8.29

7. Which of the following has maximum ionization energy
a) $Ba\rightarrow Ba^{+}+e^{-}$
b) $Be\rightarrow Be^{+}+e^{-}$
c) $Ca\rightarrow Ca^{2+}+2e^{-}$
d) $Mg\rightarrow Mg^{2+}+2e^{-}$

Explanation: $Mg\rightarrow Mg^{2+}+2e^{-}$

8. The alkaline earth metals Ba, Sr, Ca and Mg may be arranged in the order of their decreasing first ionisation potential as
a) Mg, Ca, Sr, Ba
b) Ca, Sr, Ba, Mg
c) Sr, Ba, Mg, Ca
d) Ba, Mg, Ca, Sr

Explanation: Mg, Ca, Sr, Ba

9. The first ionization energy of magnesium is lower than the first ionization energy of
a) lithium
b) sodium
c) calcium
d) beryllium