This set of Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “s-Block Elements – Anomalous Properties of Lithium”.
1. Lithium and magnesium are ____________ metals.
Explanation: Lithium and magnesium are harder than other metals in the group because they have a strong metallic bond among themselves. This is one of the similarities between Lithium and magnesium having a diagonal relation.
2. Lithium chloride is ____________ in nature.
Explanation: Both lithium chloride (LiCl) and magnesium chloride (MgCl) are predominantly covalent when compared to other elements in their respective groups, that is alkali metals and alkaline earth metals.
3. What is the difference between the Ionic radius of cations of Lithium and magnesium?
a) 2 A°
b) 0.05 A°
c) 1 A°
d) 5 A°
Explanation: The Ionic radius of Lithium cation is 0.60A°, which is very close to that of magnesium cation that is 0.65A°, therefore the difference between the Ionic radius of cations of Lithium and magnesium is 0.05A°.
4. What is the electronegativity of lithium?
Explanation: Electronegativity of Lithium is 1.0 and the electronegativity of magnesium as 1.2, they have almost similar electronegativities which is one of the reasons for Lithium and Magnesium’s diagonal relationship.
5. Which of the following statements is true regarding the diagonal relationship between Lithium and magnesium?
a) Lithium and magnesium combined with oxygen to form superoxides
b) Lithium and magnesium are soft metals
c) Lithium hydroxide and magnesium Hydroxide are weak bases
d) Magnesium chloride is completely soluble in water
Explanation: The correct statements of the incorrect ones are that; Lithium and magnesium combine with oxygen in order to form monoxides, they are hard metals and magnesium chloride is partially soluble in water as lithium chloride.
6. Which of the following element has the smallest size in its group?
Explanation: The element Lithium whose atomic number is given by 3 is the smallest element in its group that is alkali metals by size. This is one of the reasons why it has anomalous behavior in the periodic table comparatively.
7. Does Lithium react with nitrites?
c) may be
d) may not be
Explanation: Yes, Lithium which is unlike the other alkali metals, reacts with nitrogen to form the nitride six moles of lithium combine with one mole of a nitrogen atom, in order to form two moles of lithium nitride.
8. On heating lithium carbonate decomposes in order to evolve the ____________
c) carbon dioxide
Explanation: Lithium carbonate decomposes on heating in order to avoid carbon dioxide whereas other alkali metal carbonates do not evolve carbon dioxide, this occurs because lithium carbonate is unstable in the presence of heat and is the least stable among the carbonates of alkali metals.
9. Lithium has a diagonal relationship with ____________
Explanation: Lithium shows diagonal resemblance with magnesium which is an element of group 2 and this resemblance is due to the similar polarising power of both these elements. polarizability is proportional to the ionic charge / the square of the Ionic radius.
10. Lithium has the same radius that of magnesium.
Explanation: The atomic radius of Lithium is 1.31Ao while that of magnesium is 1.34Ao, though Lithium and magnesium do not have the same radius, they have a similar radius which is a reason for their diagonal relationship.
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