91. Which alkaline earth metal is used in the manufacture of cement?
- (a) Calcium
- (b) Magnesium
- (c) Strontium
- (d) Barium
Answer: (a) Calcium
Explanation: Calcium is a major component of limestone and is used in the manufacture of cement. Calcium oxide (CaO)(CaO), also known as lime, is a key ingredient in cement production.
92. Which alkali metal ion is most effective in conducting electricity in aqueous solution?
- (a) Li⁺
- (b) Na⁺
- (c) K⁺
- (d) Cs⁺
Answer: (b) Na⁺
Explanation: Sodium ion (Na+)(Na+) is small and has high mobility in aqueous solution, making it highly effective in conducting electricity.
93. Which alkaline earth metal forms a hydride used as a reducing agent in organic chemistry?
- (a) Calcium
- (b) Magnesium
- (c) Barium
- (d) Lithium
Answer: (b) Magnesium
Explanation: Magnesium hydride (MgH2)(MgH2) is used as a reducing agent in organic chemistry due to its ability to release hydrogen gas during chemical reactions.
94. Which alkali metal is most commonly used in batteries?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (a) Lithium
Explanation: Lithium is commonly used in batteries due to its high energy density, low weight, and ability to release energy efficiently.
95. Which of the following alkaline earth metal oxides is used in the manufacture of refractory bricks?
- (a) Magnesium oxide
- (b) Calcium oxide
- (c) Barium oxide
- (d) Strontium oxide
Answer: (a) Magnesium oxide
Explanation: Magnesium oxide (MgO)(MgO), also known as magnesia, is used in the manufacture of refractory bricks due to its high melting point and resistance to heat and corrosion.
96. Which of the following alkali metals has the lowest boiling point?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (d) Cesium
Explanation: Cesium has the lowest boiling point among the alkali metals due to its large atomic size and weaker metallic bonds.
97. Which of the following alkaline earth metals forms a nitrate that does not decompose on heating?
- (a) Beryllium
- (b) Magnesium
- (c) Calcium
- (d) Strontium
Answer: (b) Magnesium
Explanation: Magnesium nitrate decomposes to form magnesium oxide, nitrogen dioxide, and oxygen upon heating. The decomposition temperature varies for different nitrates, but magnesium nitrate decomposes at a relatively higher temperature than others.
98. Which alkali metal is most abundant in the Earth’s crust?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Rubidium
Answer: (b) Sodium
Explanation: Sodium is the most abundant alkali metal in the Earth’s crust, primarily found in the form of sodium chloride (NaCl) and other minerals.
99. Which alkaline earth metal forms the hardest hydride?
- (a) Calcium
- (b) Magnesium
- (c) Beryllium
- (d) Strontium
Answer: (c) Beryllium
Explanation: Beryllium hydride (BeH2)(BeH2) is hard and has a complex polymeric structure, making it much harder than the hydrides of other alkaline earth metals.
100. Which alkali metal forms a hydroxide used in soap making?
- (a) Lithium
- (b) Sodium
- (c) Potassium
- (d) Cesium
Answer: (b) Sodium
Explanation: Sodium hydroxide (NaOH), also known as caustic soda, is widely used in the manufacture of soap. It saponifies fats to produce soap and glycerol.
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