Unit 2: Classification of elements and Periodicity in Properties — Online MCQ Test
CHEMISTRY · CLASS 11 INTERMEDIATE 1 YEAR · Telangana State Board
Practice Unit 2: Classification of elements and Periodicity in Properties with a free chapter-wise online MCQ test.
This chapter covers: This chapter details periodic table development modern periodic law and s p d f block element classifications. Students examine periodic trends in atomic radii ionic radii ionizati....
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Unit 2: Classification of elements and Periodicity in Properties — Important Questions & Answers
Which law states that the properties of elements are periodic functions of their atomic numbers?
- A. Moseley’s law
- B. Modern periodic law
- C. Dalton’s atomic theory
- D. Avogadro’s law
Answer: B. Modern periodic law
The modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers.
The modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers.
The element with atomic number 11 belongs to which block of the periodic table?
- A. s-block
- B. p-block
- C. d-block
- D. f-block
Answer: A. s-block
Atomic number 11 is sodium, and its valence electron enters the 3s orbital, so it belongs to the s-block.
Atomic number 11 is sodium, and its valence electron enters the 3s orbital, so it belongs to the s-block.
As we move from left to right across a period, the ionization enthalpy generally:
- A. decreases steadily
- B. increases steadily
- C. remains constant
- D. first increases and then decreases sharply for all elements
Answer: B. increases steadily
Ionization enthalpy generally increases across a period because effective nuclear charge increases and atomic size decreases.
Ionization enthalpy generally increases across a period because effective nuclear charge increases and atomic size decreases.
A student observes that element X is in Group 17 and Period 3. Which valence-shell configuration is correct for X?
- A. 3s2 3p5
- B. 3s1 3p6
- C. 2s2 2p5
- D. 3s2 3p3
Answer: A. 3s2 3p5
Group 17 elements have ns2 np5 valence configuration, and Period 3 means n = 3, so the configuration is 3s2 3p5.
Group 17 elements have ns2 np5 valence configuration, and Period 3 means n = 3, so the configuration is 3s2 3p5.
Which element is correctly placed in the p-block but has the electron configuration ending in 4p1?
- A. Aluminium
- B. Gallium
- C. Boron
- D. Indium
Answer: B. Gallium
Gallium has the valence-shell configuration [Ar] 3d10 4s2 4p1, so its last electron enters a p-orbital in the 4th period.
Gallium has the valence-shell configuration [Ar] 3d10 4s2 4p1, so its last electron enters a p-orbital in the 4th period.