Answer: The correct option is (D) lithium (Li).
Explanation: Hydrogen is the element which belong to period 1. The atomic number of hydrogen is, 1
The electronic configuration of hydrogen is,
The number of valence electrons present in hydrogen is, 1.
(A) Helium is the element which belong to period 1. The atomic number of helium is, 2
The electronic configuration of helium is,
The number of valence electrons present in helium is, 2.
(B) Oxygen is the element which belong to period 2. The atomic number of oxygen is, 8
The electronic configuration of oxygen is,
The number of valence electrons present in oxygen is, 6.
(C) Nitrogen is the element which belong to period 2. The atomic number of nitrogen is, 7
The electronic configuration of nitrogen is,
The number of valence electrons present in nitrogen is, 5.
(D) Lithium is the element which belong to period 2. The atomic number of lithium is, 3
The electronic configuration of lithium is,
The number of valence electrons present in lithium is, 1.
From this we conclude that the lithium element has the same number of valence electrons as hydrogen.
Hence, the correct option is (D) lithium (Li).
