Chapter 3: Periodic Classification Of Elements — Online MCQ Test
CHEMISTRY · CLASS 11th · Tamil Nadu State Board
Practice Chapter 3: Periodic Classification Of Elements with a free chapter-wise online MCQ test.
This chapter covers: This chapter covers periodic table development modern periodic law and periodic property trends. Students study atomic radii ionic radii ionization energy electron affinity electro....
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Chapter 3: Periodic Classification Of Elements — Important Questions & Answers
Which scientist proposed the Law of Triads?
- A. Dobereiner
- B. Newlands
- C. Mendeleev
- D. Lothar Meyer
Answer: A. Dobereiner
Johann Wolfgang Dobereiner observed that in groups of three elements (triads), the atomic weight of the middle element was approximately the average of the other two.
Johann Wolfgang Dobereiner observed that in groups of three elements (triads), the atomic weight of the middle element was approximately the average of the other two.
What is the general electronic configuration of d-block elements?
- A. (n-1)d^1-10 ns^0-2
- B. ns^1-2
- C. (n-1)d^1-10 ns^2
- D. ns^2 np^1-6
Answer: A. (n-1)d^1-10 ns^0-2
The d-block elements involve the filling of inner d-orbitals, represented by the configuration (n-1)d^1-10 ns^0-2.
The d-block elements involve the filling of inner d-orbitals, represented by the configuration (n-1)d^1-10 ns^0-2.
Which periodic property decreases from left to right across a period?
- A. Ionization energy
- B. Electronegativity
- C. Atomic radius
- D. Electron affinity
Answer: C. Atomic radius
As effective nuclear charge increases across a period, the electrons are pulled closer to the nucleus, decreasing the atomic radius.
As effective nuclear charge increases across a period, the electrons are pulled closer to the nucleus, decreasing the atomic radius.
Why is the electron gain enthalpy of Chlorine more negative than that of Fluorine?
- A. Chlorine is more electronegative
- B. Fluorine has a smaller size causing inter-electronic repulsion
- C. Chlorine has a higher atomic mass
- D. Fluorine is a gas
Answer: B. Fluorine has a smaller size causing inter-electronic repulsion
Due to the small size of the fluorine atom, the incoming electron experiences repulsion from existing electrons, making the process less exothermic compared to Chlorine.
Due to the small size of the fluorine atom, the incoming electron experiences repulsion from existing electrons, making the process less exothermic compared to Chlorine.
Which element has an anomalous electronic configuration involving a shift from the 4s orbital to the 3d orbital to achieve half-filled stability?
- A. Scandium
- B. Chromium
- C. Iron
- D. Titanium
Answer: B. Chromium
Chromium (Z=24) has the configuration [Ar] 3d5 4s1 to gain the extra stability of a half-filled d-subshell.
Chromium (Z=24) has the configuration [Ar] 3d5 4s1 to gain the extra stability of a half-filled d-subshell.