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Consider two elements X and Y where X has atomic number 15 and Y has atomic number 16. According to the Modern Periodic Law, which of the following is true about their chemical properties?

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Free Technical Assistant( Kerala Drugs Control ) Practice Questions

Kerala Public Service CommissionRecruitment for the post of Technical Assistant in Kerala Drugs Control Department. The role involves scientific duties with a pay scale of ā‚¹35,600 - 75,400. Direct recruitment with age limits and qualification criteria apply.Direct RecruitmentDegree in Science with Chemistry required

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Q1. Consider two elements X and Y where X has atomic number 15 and Y has atomic number 16. According to the Modern Periodic Law, which of the following is true about their chemical properties?

  1. They have completely different chemical properties because their atomic masses differ.
  2. They have similar chemical properties because they are in the same group.
  3. They have different chemical properties because they belong to different groups.
  4. Their chemical properties depend only on their physical states.

Q2. Given the ionic radii of O2- (140 pm), F- (133 pm), and Na+ (102 pm), which of the following statements is true regarding their sizes?

  1. O2- is smaller than F- due to higher nuclear charge
  2. Na+ is the smallest because it has the highest positive charge
  3. F- is larger than O2- because it has fewer electrons
  4. All ions have the same size because they are isoelectronic

Q3. How did the discovery of atomic number influence the arrangement of elements in the Modern Periodic Table?

  1. It allowed elements to be arranged by increasing atomic mass.
  2. It resolved anomalies in Mendeleev's periodic table by arranging elements by nuclear charge.
  3. It grouped elements based on their melting points.
  4. It led to the classification of elements by their isotopic masses.

Q4. Calculate the effective nuclear charge (Zeff) experienced by the outermost electrons of Mg2+ ion, given that Mg has atomic number 12 and the shielding constant (S) for the 10 electrons is approximately 10. Use Zeff = Z - S.

  1. 2
  2. 10
  3. 12
  4. 22

Q5. Consider two elements, X and Y, in the same group of the periodic table where Y is below X. Which statement correctly compares their atomic radii?

  1. Element X has a larger atomic radius than element Y.
  2. Element Y has a larger atomic radius than element X.
  3. Both elements have the same atomic radius.
  4. Atomic radius depends only on the number of protons, so cannot be compared.

Q6. Which of the following best explains the trend in ionic radii of isoelectronic ions as the atomic number increases?

  1. Ionic radius increases due to more electron-electron repulsion
  2. Ionic radius decreases due to increasing nuclear charge pulling electrons closer
  3. Ionic radius remains constant because the number of electrons is the same
  4. Ionic radius fluctuates randomly with atomic number

Q7. Arrange the following factors in order of their influence on ionization enthalpy from most to least significant:1. Effective nuclear charge2. Atomic radius3. Electron shielding4. Subshell configuration stability

  1. 1 > 2 > 3 > 4
  2. 2 > 1 > 4 > 3
  3. 3 > 1 > 2 > 4
  4. 4 > 3 > 2 > 1

Q8. Calculate the approximate atomic radius of an element if the effective nuclear charge (Z_eff) experienced by its outermost electron is 5 and the principal quantum number (n) is 3, using the simplified formula: Atomic radius āˆ nĀ² / Z_eff. Which of the following values is closest?

  1. 1.8 (arbitrary units)
  2. 2.4 (arbitrary units)
  3. 3.6 (arbitrary units)
  4. 5.0 (arbitrary units)

Q9. Which factor primarily causes the atomic radius to decrease when moving from left to right across a period in the periodic table?

  1. Increase in number of electron shells.
  2. Increase in effective nuclear charge without significant increase in shielding.
  3. Decrease in nuclear charge.
  4. Increase in electron-electron repulsion in the outer shell.

Q10. Which of the following trends correctly describes the variation of first ionization enthalpy across a period in the modern periodic table?

  1. It decreases from left to right across a period
  2. It remains constant across a period
  3. It generally increases from left to right across a period
  4. It fluctuates randomly with no trend

Q11. Consider the ions Na+, Mg2+, and Al3+. Which of the following correctly ranks their ionic radii from largest to smallest?

  1. Na+ > Mg2+ > Al3+
  2. Al3+ > Mg2+ > Na+
  3. Mg2+ > Na+ > Al3+
  4. Na+ > Al3+ > Mg2+

Q12. Which factor primarily causes the decrease in ionization enthalpy down a group in the periodic table?

  1. Increase in nuclear charge
  2. Increase in atomic radius and shielding effect
  3. Decrease in number of electrons
  4. Increase in effective nuclear charge

Q13. The atomic number of an element is 20. Using the Modern Periodic Law, predict the group and period of this element in the periodic table.

  1. Group 2, Period 4
  2. Group 18, Period 3
  3. Group 1, Period 4
  4. Group 16, Period 4

Q14. Consider two elements, X and Y, where X has a smaller atomic radius but lower ionization enthalpy than Y. Which factor could explain this anomaly?

  1. Higher electron shielding in X
  2. X has a half-filled or fully filled subshell
  3. Y has a higher effective nuclear charge
  4. X has more protons than Y

Q15. Which of the following best explains the general trend in atomic radii across a period in the modern periodic table?

  1. Atomic radius increases due to increasing number of protons.
  2. Atomic radius decreases due to increasing effective nuclear charge.
  3. Atomic radius remains constant because electron shielding is unchanged.
  4. Atomic radius increases due to addition of electron shells.
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