Correct Answer - Option 4 : D
The correct answer is Hydrogen.
- Hydrogen is not an inert gas.
- It comes under the S-block elements.
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S-Block:
- It contains groups 1 and 2, i.e., hydrogen and alkali metals (Li, Na, K, Rb, Cs, Fr) and alkaline earth metals (Be, Mg, Ca, Sr, Ba, Ra).
- The general electronic configuration of these elements is ns0-2.
- These elements are soft metals, electropositive.
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Inert Gases:
- They belong to the 18th group of Periodic Table. For example, He, Ne, Ar, Kr, Xe, Rn.
- Except for Rn, all inert gases are present in the atmosphere.
- Argon is used in Arc. welding and electric bulbs.
- Helium is light and non-inflammable so, used in a balloon, weather indicator, etc.
- Neon is used in discharge tube glow light.
- The atom of hydrogen is the smallest and lightest.
- Hydrogen is the only atom in which neutrons are not present.
- Elements have the following order of abundance in the human body:
- Oxygen >carbon> hydrogen > nitrogen.