Some p‑Block Elements Quiz - ICSE Class 11 Chemistry
Free practice quiz: Some p‑Block Elements (ICSE Class 11 Chemistry). 13 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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The anomalous behavior of Boron compared to other elements in Group 13 is attributed to:
- Its small atomic size and high electronegativity
- Its inability to form a chloride that sublimes
- Its electropositive character
- The presence of unpaired electrons in its valence shell
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Answer: A. Its small atomic size and high electronegativity
Boron's anomalous behavior is primarily due to its small atomic size, high ionization enthalpy, and high electronegativity compared to other Group 13 elements. These properties lead to its unique chemistry, such as the formation of covalent compounds and the tendency to form electron-deficient species like boranes.
The increasing order of reactivity of halogens with hydrogen is:
- F2 > Cl2 > Br2 > I2
- I2 > Br2 > Cl2 > F2
- F2 < Cl2 < Br2 < I2
- Cl2 > Br2 > F2 > I2
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Answer: A. F2 > Cl2 > Br2 > I2
The reactivity of halogens with hydrogen increases from Iodine to Fluorine. This is because the bond dissociation enthalpy of H-X decreases down the group (H-F > H-Cl > H-Br > H-I), making the reaction with hydrogen more facile as the bond is weaker. Fluorine is the most reactive and reacts explosively with hydrogen.
Which acid is formed when P4O10 reacts with excess hot water?
- Phosphorous acid (H3PO3)
- Orthophosphoric acid (H3PO4)
- Metaphosphoric acid (HPO3)
- Pyrophosphoric acid (H4P2O7)
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Answer: C. Metaphosphoric acid (HPO3)
When P4O10 reacts with excess hot water, it initially forms orthophosphoric acid, which then dehydrates to form metaphosphoric acid. Further heating or reaction can lead to the formation of pyrophosphoric acid and polyphosphoric acids.
The inert pair effect is most significant in which period for p-block elements?
- Period 2
- Period 3
- Period 4
- Period 6
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Answer: D. Period 6
The inert pair effect, which is the reluctance of the valence s-electrons to participate in bonding, becomes increasingly pronounced down a group, particularly in Period 6 elements. This is due to the presence of intervening f-electrons (lanthanides) which poorly shield the nuclear charge, causing the valence s-electrons to be held more tightly by the nucleus. This effect is prominently observed in the heavier elements of Groups 13, 14, 15, and 16.
Which of the following is NOT a characteristic property of Lithium?
- It forms a stable nitride (Li3N).
- Its chloride (LiCl) is soluble in water.
- It forms a monoxide (Li2O) as the principal oxide.
- It forms a bicarbonate (LiHCO3) which is insoluble in water.
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Answer: D. It forms a bicarbonate (LiHCO3) which is insoluble in water.
Lithium is the only alkali metal that forms a stable nitride (Li3N). Its chloride (LiCl) is indeed soluble in water due to its high lattice energy. The principal oxide of lithium is lithium monoxide (Li2O), unlike other alkali metals which primarily form peroxides or superoxides. Crucially, lithium bicarbonate (LiHCO3) is soluble in water, unlike the bicarbonates of other alkali metals which are less soluble or insoluble. This solubility of LiHCO3 is an anomalous property.