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Class 10  ยป  Chemistry  ยป  Periodic Classification of Elements

Modern Periodic Table Moseley - UNSOLVED PRACTICE SET

Class 10

Chapter: Periodic Classification of Elements | Topic: Modern Periodic Table Moseley

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Study Material.
Class 10

MODERN PERIODIC TABLE MOSELEY - UNSOLVED PRACTICE SET

Topic: Modern Periodic Table Moseley

Time: 40 mins | Marks: 30 | Difficulty: Medium

Multiple Choice Questions

Q1. The modern periodic law was proposed by:

  1. Mendeleev
  2. Moseley
  3. Newlands
  4. Dobereiner

Q2. According to the modern periodic law, the properties of elements are a periodic function of their:

  1. Atomic mass
  2. Atomic number
  3. Number of neutrons
  4. Mass number

Q3. Moseley discovered that the property most closely related to an element's chemical behaviour is:

  1. Atomic mass
  2. Number of protons (atomic number)
  3. Number of neutrons
  4. Density

Q4. The modern periodic table has how many periods and groups?

  1. 7 periods and 8 groups
  2. 8 periods and 18 groups
  3. 7 periods and 18 groups
  4. 18 periods and 7 groups

Q5. Which scientist established the relationship between the frequency of X-rays and the atomic number of elements?

  1. Rutherford
  2. Bohr
  3. Moseley
  4. Chadwick

Q6. The modern periodic table resolves the problem of isotopes because:

  1. Isotopes have different atomic numbers
  2. Isotopes have the same atomic number but different atomic masses
  3. Isotopes are placed in different groups
  4. Isotopes do not exist in the modern periodic table

Short Answer Questions

Q7. State the modern periodic law. How is it different from Mendeleev's periodic law?

Q8. What was Moseley's contribution to the development of the periodic table? Why was it considered revolutionary?

Q9. Why are isotopes of an element placed in the same position in the modern periodic table?

Q10. How many elements are present in the 4th period of the modern periodic table? Why does this period have more elements than the 3rd period?

Q11. Your physics teacher explains that Moseley used X-ray experiments to study elements. He found that when he sorted elements by atomic number, everything fell into place perfectly. Why was atomic number a better basis than atomic mass for arranging elements? 

Q12. Write the electronic configuration of an element with atomic number 17. In which period and group would you place it in the modern periodic table?

Long Answer Questions

Q13. Explain how Moseley's work led to the modern periodic law. Describe his X-ray experiments and how they proved that atomic number is more fundamental than atomic mass. Why did the modern periodic table solve problems that Mendeleev's table could not? 

Q14. Compare Mendeleev's periodic table with the modern periodic table on the following points:

(a) Basis of arrangement

(b) Position of isotopes

(c) Position of cobalt and nickel

(d) Position of hydrogen

Why is the modern periodic table considered more accurate?

Q15. During a class discussion, your teacher asks: "If Mendeleev had known about atomic numbers, how would his table have been different?"

(a) Would tellurium and iodine still need to be reversed? Explain.

(b) How would the position of argon and potassium be resolved?

(c) Would isotopes of chlorine (Cl-35 and Cl-37) be placed separately or together? Why?

(d) Why does the modern periodic table have 18 groups instead of Mendeleev's 8 groups?

Numerical / Application-Based Problems

Q16. The atomic number of an element X is 20.

(a) Write its electronic configuration.

(b) Determine its period and group in the modern periodic table.

(c) How many valence electrons does it have? What is its valency?

Q17. Moseley found that the square root of the frequency of X-rays emitted by an element (โˆšฮฝ) is directly proportional to its atomic number (Z).

(a) If element A (Z = 13) emits X-rays of frequency 4 units, calculate the expected frequency of X-rays for element B (Z = 26) using Moseley's law.

(b) Why does this relationship prove that atomic number is more fundamental than atomic mass?

(c) An element has an atomic mass of 63.5 u but its atomic number is 29. Another element has an atomic mass of 65 u but atomic number 30. Which element would come first in the modern periodic table? Why?

Q18. A student is given the following data about three elements:

Table

Element Atomic Mass (u) Atomic Number

P 40 20

Q 39 19

R 40 18

(a) Arrange these elements in the correct order as they appear in the modern periodic table.

(b) Which two elements would have been placed incorrectly if arranged by atomic mass (Mendeleev's method)?

(c) Write the electronic configuration of each element and verify their positions in the periodic table.

Total: 30 Marks | Time: 40 mins

Explore more topics in Periodic Classification of Elements

Early Classification Attempts Dobereiner Newlands Mendeleevs Periodic Table Merits and Limitations Periods and Groups Trends in the Periodic Table Atomic Size Metallic Character Valency across Periods and Groups Metals Non Metals and Metalloids in the Table