Important MCQs on The s-Block Elements with Explanation

Ans. (D) Mg

Explanation: Magnesium is the core atom of the chlorophyll molecule. A single chlorophyll molecule constitutes 6.7% of magnesium. It acts as a catalyst by activating enzymes involved in nucleic acid synthesis, respiration, and photosynthesis.

Ans. (B) Calcium Hydroxide

Explanation: Calcium Hydroxide is conventionally termed slaked lime. It is a colorless and crystalline white powder formed upon slaking calcium oxide with water. This process is termed hydration or lime slaking.

Ans. (A) Cs

Explanation: As the element is large in size, Cs (Cesium) has the least electron-proton attraction causing it to easily lose its electron to attain the most stable state. Thus, making it a highly electropositive element.

Ans. (B) Deep blue

Explanation: Alkali metals turn to deep blue color as the alkali atom easily loses the valence electron in liquid ammonia. It combines with ammonia to form ammoniated cations and ammoniated electrons. The solution turns deep blue due to the presence of ammoniated electrons.

Read More: Difference between Cations and Anions

Ans. (C) Be 

Explanation: Be (Beryllium) is small in size and contains only 2 electrons in the outermost valence shell. Considering it has a high charge-to-size ratio, Be has a high polarizing potential compared to other elements that resultantly form covalent bonds. 

Ans. (A) Manufacturing of Sodium Carbonate

Explanation: Also, termed the ammonia-soda process, the Solvay process is an industrial method used for extracting Sodium Carbonate from brine, ammonia, and limestone. It is named after the Belgian chemist, Ernest Solvay.

Ans. (C) BeO

Explanation: BeO has both basic and acidic properties. Beryllium is the only alkaline earth metal that is insoluble and non-reactive in water. Because the size of this element is small and ionization energy is high relative to other elements of the group.

Ans. (D) Cs

Explanation: The size of the metal is inversely proportional to the strength of its metallic bonding. As the size of the metal increases, metallic bonding decreases and vice-versa. As the size of Cs is the biggest, its melting point is the lowest.

Ans. (A) Al

Explanation: Be and Al are placed in the second and third periods of the periodic table respectively, displaying a diagonal placement. They have similar ionic sizes and charge ratios. Both metals exhibit tendency to form covalent bonds.

Read More: Ionic Radius

Ques 10. Which of the below-mentioned alkali metals forms hydrated salts?

Ans. (A) Li

Explanation: Lithium is the smallest in size amongst the alkali metal ions. Thus, it exhibits the highest charge density. And attracts the water molecules strongly compared to other alkali metal cations.

Ans. (D) Mg

Explanation: Mg filaments are used in bulbs filled with oxygen gas. These filaments react with oxygen to form a compound called Magnesium Oxide (MgO). The bright white light is a result of this exothermic reaction. Upon ignition, Mg releases a lot of heat in the form of light.

Ans. (A) Barium Carbonate

Explanation: Moving down the periodic table, the electro-positiveness of the alkaline earth metals increases. Consequently, the thermal stability also increases. As the positive ions get bigger down the periodic table, their effect on the near carbonate ion declines. Thus, Barium Carbonate has the most thermal stability.

Ans. (B) K

Explanation: Potassium Peroxide is used in the oxygen cylinders of the spacecraft. As it absorbs Carbon Dioxide and releases pure Oxygen at high altitudes. Thus, purifying the air.

Ans. (D) It transforms into calcium chlorate and calcium chloride

Explanation: Bleaching powder is unstable and long-standing reduces its chlorine content. Due to auto-oxidation, it transforms into calcium chlorate and calcium chloride.

Ans. (C) Diamagnetic

Explanation: The absence of unpaired electrons and noble gas configuration makes alkaline earth metals diamagnetic.

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