Which is the first element on the periodic table?

Correct option is D

The correct answer is (d) Hydrogen

Explanation:

Hydrogen (H) is the first element in the periodic table with an atomic number of 1.

• It is the lightest and most abundant element in the universe.
• Hydrogen is a non-metal but is sometimes placed in Group 1 (alkali metals) due to its single electron.
• It exists as a diatomic molecule (H₂) in nature and is used in fuel cells, ammonia production, and rocket fuel.

Information Booster:

Key Properties of Hydrogen:

• Atomic Number: 1
• Atomic Mass: 1.008 u
• Symbol: H
• State at Room Temperature: Gas
• Most Abundant in: Stars, the Sun, and gas planets.

Why is Hydrogen Important?

• Used in fuel cells for clean energy.
• Essential for water formation (H₂O).
• Key component in organic molecules.

Additional Knowledge:

Oxygen (O₂)

• Symbol: O
• Atomic Number: 8
• Atomic Mass: 16 u
• Electronic Configuration: 1s² 2s² 2p⁴
• Allotropes: O₂ (dioxygen, essential for life), O₃ (ozone, protects from UV radiation).

Nitrogen (N₂)

• Symbol: N
• Atomic Number: 7
• Atomic Mass: 14 u
• Electronic Configuration: 1s² 2s² 2p³
• Allotropes: Exists as diatomic nitrogen (N₂) under normal conditions.