- Which of the following elements has the highest atomic number?
A) Oxygen
B) Fluorine
C) Nitrogen
D) Neon
Answer: D) Neon
Explanation: Among these elements, neon (Ne) has the highest atomic number, 10. Atomic numbers increase as you move from left to right across a period.
- Which of the following is the correct order of atomic radius?
A) Na > K > Rb > Cs
B) Cs > Rb > K > Na
C) Na < K < Rb < Cs D) Cs < Rb < K < Na Answer: B) Cs > Rb > K > Na
Explanation: Atomic radius increases down a group because additional electron shells are added, which increases the distance between the nucleus and the outermost electrons.
- The first element of each period in the periodic table has:
A) One electron in its valence shell
B) A complete octet in its valence shell
C) Two electrons in its valence shell
D) A valency of zero
Answer: A) One electron in its valence shell
Explanation: The first element of each period is an alkali metal (Group 1), which has one electron in its outermost shell, making it highly reactive.
- The electron configuration of an element is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s². What is the element?
A) Calcium
B) Magnesium
C) Potassium
D) Zinc
Answer: A) Calcium
Explanation: The given configuration represents calcium (Ca), which has 20 electrons (atomic number 20). The configuration ends in 4s², indicating that calcium is in Group 2.
- Which of the following groups contains only transition elements?
A) Group 2
B) Group 3-12
C) Group 15
D) Group 18
Answer: B) Group 3-12
Explanation: Transition elements are located in Groups 3-12 of the periodic table. They are characterized by their ability to form colored compounds and variable oxidation states.
- Which element is known as a noble gas?
A) Hydrogen
B) Oxygen
C) Argon
D) Nitrogen
Answer: C) Argon
Explanation: Noble gases are elements in Group 18 of the periodic table. Argon (Ar) is one of the noble gases, known for its lack of reactivity due to its full valence shell.
- Which of the following statements is true about alkali metals?
A) They form acidic oxides
B) They have low reactivity
C) They form basic oxides
D) They have high melting points
Answer: C) They form basic oxides
Explanation: Alkali metals (Group 1) form basic oxides when they react with oxygen. For example, sodium forms sodium oxide (Na₂O), which is basic in nature.
- Which of the following is an s-block element?
A) Iron
B) Potassium
C) Chlorine
D) Zinc
Answer: B) Potassium
Explanation: Potassium (K) belongs to Group 1, which is part of the s-block. Elements in this block have their valence electrons in s-orbitals.
- Which of the following elements has a half-filled p-subshell in its ground state?
A) Nitrogen
B) Oxygen
C) Neon
D) Sulfur
Answer: A) Nitrogen
Explanation: Nitrogen has an electron configuration of 1s² 2s² 2p³. A p-subshell can hold up to six electrons, and with three electrons in its p-orbital, nitrogen has a half-filled p-subshell.
- What is the period number of an element with the electron configuration 1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁵?
A) Period 3
B) Period 4
C) Period 5
D) Period 6
Answer: B) Period 4
Explanation: The element has electrons filling up to the 4th shell, so it belongs to Period 4. The configuration matches that of bromine (Br), which is in Period 4.
Leave a comment