“Periodic Table” MCQ with Answer Explanation.

31. Which of the following elements shows maximum number of oxidation states?
    A) Scandium
    B) Titanium
    C) Vanadium
    D) Chromium
    Answer: D) Chromium

Explanation: Chromium (Cr) can exhibit a variety of oxidation states, the most common being +2, +3, and +6. The availability of multiple oxidation states is due to the presence of both s and d electrons.

32. Which of the following groups contains only nonmetals?
    A) Group 1
    B) Group 14
    C) Group 16
    D) Group 2
    Answer: C) Group 16

Explanation: Group 16 elements (oxygen, sulfur, selenium) are nonmetals. These elements, also known as the chalcogens, have six electrons in their outermost shell and are chemically reactive.

33. The most electronegative element in Group 17 is:
    A) Chlorine
    B) Bromine
    C) Fluorine
    D) Iodine
    Answer: C) Fluorine

Explanation: Fluorine is the most electronegative element in the periodic table, with an electronegativity value of 3.98 on the Pauling scale. Its small atomic radius and high nuclear charge make it highly effective at attracting electrons.

34. Which element has the electron configuration [Ne] 3s² 3p¹?
    A) Magnesium
    B) Aluminum
    C) Silicon
    D) Phosphorus
    Answer: B) Aluminum

Explanation: The electron configuration [Ne] 3s² 3p¹ corresponds to aluminum (Al). It has 13 electrons, with the outermost three electrons located in the 3s and 3p orbitals.

35. Which of the following elements has the lowest first ionization energy?
    A) Oxygen
    B) Nitrogen
    C) Fluorine
    D) Carbon
    Answer: D) Carbon

Explanation: Among the given options, carbon (C) has the lowest ionization energy. As you move across a period, ionization energy increases due to the stronger attraction between the nucleus and electrons. Fluorine has the highest, and carbon the lowest, ionization energy in this group.

36. Which of the following elements is a post-transition metal?
    A) Iron
    B) Copper
    C) Tin
    D) Titanium
    Answer: C) Tin

Explanation: Post-transition metals are located to the right of the transition metals in the periodic table. Tin (Sn) is a post-transition metal, exhibiting metallic properties but being softer and having lower melting points compared to transition metals.

37. Which of the following elements has the highest atomic mass?
    A) Nitrogen
    B) Phosphorus
    C) Arsenic
    D) Antimony
    Answer: D) Antimony

Explanation: Among the given options, Antimony (Sb) has the highest atomic mass. Atomic mass increases as you move down a group and across a period from left to right.

38. Which element is a liquid at room temperature?
    A) Bromine
    B) Chlorine
    C) Iodine
    D) Fluorine
    Answer: A) Bromine

Explanation: Bromine (Br) is one of the two elements that are liquid at room temperature, the other being mercury. It is a halogen with distinct reddish-brown color in its liquid form.

39. Which of the following elements has sp³ hybridization in its ground state?
    A) Beryllium
    B) Boron
    C) Carbon
    D) Nitrogen
    Answer: C) Carbon

Explanation: Carbon in its ground state has sp³ hybridization, forming four equivalent sp³ hybrid orbitals that participate in forming four sigma bonds, as seen in methane (CH₄).

40. Which element has the electron configuration [Kr] 4d¹⁰ 5s² 5p⁴?
    A) Tin (Sn)
    B) Antimony (Sb)
    C) Tellurium (Te)
    D) Iodine (I)
    Answer: C) Tellurium

Explanation: The electron configuration [Kr] 4d¹⁰ 5s² 5p⁴ corresponds to Tellurium (Te), which is in Group 16 of the periodic table.