This set of Chemistry Multiple Choice Questions & Answers (MCQs) focuses on “s-Block Elements – General Characteristics of the Compounds of the Alkali Metals”.
1. Which of the following mixture is known as fusion mixture?
a) Sodium carbonate and potassium chloride
b) Sodium carbonate and potassium carbonate
c) Sodium bicarbonate and sodium carbonate
d) Potassium bicarbonate and sodium carbonate
Explanation: The mixture of sodium carbonate and potassium carbonate together is known as a fusion mixture. Only Potassium carbonate is as known as pearl ash. It is sometimes used in quantitative analysis.
2. The solubility of carbonates _____________ down the group.
a) is irregular
b) remains the same
Explanation: The solubility of carbonates and bicarbonates of alkali metals increases on moving down the group, this is due to the increase in lattice enthalpies. The order is as follows in an increasing way of lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, rubidium bicarbonate, and cesium bicarbonate.
3. On heating Lithium nitrate which of the following compound is not formed?
b) Lithium oxide
c) Nitrous oxide
Explanation: On heating, lithium nitrate decomposes to give nitrous oxide, oxygen, and lithium oxide whereas the nitrates of other alkali metals decompose on heating and give nitrites and oxygen. Therefore hydrogen isn’t formed.
4. Which of the following is called as Chile saltpeter?
a) Rubidium nitrate
b) Sodium nitrate
c) Lithium nitrate
d) Potassium Nitrate
Explanation: Sodium nitrate (NaNo3) is called Chile saltpeter and potassium nitrate (KNO3) is called Indian saltpeter. Chile saltpeter which is Sodium nitrate is commonly and naturally found in Chile and Peru.
5. Which of the following as a chemical formula of Glauber’s salt?
Explanation: Glauber’s salt contains two atoms of sodium, one atom of sulfur, 4 atoms of oxygen, and 10 moles of water. It is the sulfate of sodium and is represented chemically as NaSO4.10H2O. It is soluble in water.
6. Which of the following alkali metal cannot form superoxide?
Explanation: All the alkali metals when heated with oxygen form different types of oxides. Lithium forms lithium oxide and some amount of lithium peroxide, while Sodium, Potassium, rubidium, and cesium can form superoxide.
7. Which of the following is true regarding the basic strength?
a) Potassium oxide is more basic than cesium oxide
b) Lithium oxide is more basic than sodium oxide
c) Cesium oxide is more basic than potassium oxide
d) Sodium oxide is more basic than cesium oxide
Explanation: All the oxides, peroxides and superoxides of alkali metals which are formed when heated with oxygen are basic in nature. The basic strength of oxides increases in the order of lithium oxide, sodium oxide, potassium oxide, and cesium oxide.
8. Superoxides are colored and _____________
Explanation: All the superoxides of alkali metals are colored and paramagnetic, as they possess three electrons bond where one unpaired electron is present. Few examples of superoxide are potassium superoxide, rubidium superoxide, and cesium superoxide.
9. Lithium chloride is more covalent than potassium chloride.
Explanation: Lithium chloride is more covalent than Potassium Chloride, due to the smaller size of lithium bigger the onion, larger as its polarizability and the covalent character follow the order of Lithium iodide is greater than Lithium Bromide, greater than lithium chloride, greater than Lithium fluoride.
10. Which of the following is true regarding the reactivity of alkali metals towards a particular halogen?
a) Rubidium is greater than that of sodium
b) Sodium is greater than that of lithium
c) Lithium is greater than that of rubidium
d) Rubidium is greater than that of cesium
Explanation: Alkali metals combine readily with halogens to form ionic halides. The reactivity order of alkali metals towards a particular halogen increase in the order; lithium, sodium, potassium, rubidium, and cesium.
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