Periodic Properties & Variations Quiz - ICSE Class 10 Chemistry
Free practice quiz: Periodic Properties & Variations (ICSE Class 10 Chemistry). 55 multiple-choice questions with answers and explanations. Play online, no sign-up needed.
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Which of the following trends is INCORRECT for elements across a period in the periodic table?
- Atomic radius generally decreases.
- Electronegativity generally increases.
- Ionization energy generally decreases.
- Metallic character generally decreases.
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Answer: C. Ionization energy generally decreases.
Across a period, the nuclear charge increases while the shielding effect remains relatively constant. This stronger attraction pulls the valence electrons closer to the nucleus, causing the atomic radius to decrease. The increased effective nuclear charge also leads to a general increase in electronegativity. The tendency to lose electrons (metallic character) decreases as elements become more electronegative. Ionization energy generally increases across a period due to the increased effective nuclear charge, making it harder to remove an electron.
The ionization energies of the first three elements in a period are I1, I2, and I3. If I1 < I2 << I3, which group do these elements likely belong to?
- Group 1
- Group 2
- Group 13
- Group 14
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Answer: B. Group 2
The first ionization energy (I1) refers to the removal of the first electron, the second ionization energy (I2) to the removal of the second electron from the same atom, and so on. A large jump in ionization energy occurs when an electron is removed from a more stable electron shell. If I1 < I2 << I3, it means the first two electrons are relatively easy to remove, but the third electron is much harder to remove. This indicates that the element has two valence electrons that are readily lost to achieve a stable electron configuration (like a noble gas). Elements in Group 2 have two valence electrons (ns^2), and their ionization energies follow this pattern: I1 < I2 << I3.
Which statement best explains the decrease in atomic radius across a period?
- The number of electron shells increases.
- The nuclear charge increases, pulling electrons closer.
- The shielding effect of inner electrons increases significantly.
- The attraction between protons and electrons decreases.
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Answer: B. The nuclear charge increases, pulling electrons closer.
Across a period, elements gain protons in the nucleus, increasing the nuclear charge. The added electrons are in the same principal energy shell, so the shielding effect of inner electrons does not increase proportionally to the nuclear charge. The increased nuclear charge exerts a stronger attractive force on the valence electrons, pulling them closer to the nucleus and thus decreasing the atomic radius.
Which of the following oxides is basic?
- CO2
- SO3
- P4O10
- K2O
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Answer: D. K2O
The oxides of metals are generally basic, while the oxides of nonmetals are generally acidic. Potassium (K) is an alkali metal. Carbon (C), Sulfur (S), and Phosphorus (P) are nonmetals. Therefore, Potassium oxide (K2O) is a basic oxide.
The formation of a stable oxide layer on the surface of Aluminum is due to:
- Its high metallic character.
- Its low ionization energy.
- The formation of a protective oxide film.
- Its inert nature.
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Answer: C. The formation of a protective oxide film.
Aluminum is a reactive metal, but it forms a thin, tenacious, and impermeable layer of aluminum oxide (Al2O3) on its surface when exposed to air. This oxide layer passivates the metal, preventing further reaction with oxygen or other corrosive agents, thus making it appear less reactive than expected for its position in the periodic table.