Explanation

Oxygen was discovered in 1774 by English chemist Joseph Priestley,

He isolated it by heating mercuric oxide and called it "dephlogisticated air".

Oxygen was discovered independently by Carl Wilhelm Scheele (around 1772)

Explanation

• Compounds with the same molecular formula but different arrangements of atoms are called isomers.
• Isomers can have different chemical and physical properties despite having the same number of atoms.

• Additional information:
  • Example of isomers: C₂H₆O → Ethanol (CH₃CH₂OH) and Dimethyl ether (CH₃OCH₃)
  • Isomerism is classified into structural isomers and stereoisomers.

Explanation

• Glycerin (glycerol) is a colorless, odorless, and viscous liquid.
• It is commonly used in pharmaceuticals, cosmetics, and food products.

Additional information:

• Glycerin is non-toxic and safe in small quantities.
• It acts as a humectant, helping retain moisture.

Last verified on 20-01-2026

Explanation

• Carbon has a valency of 4, meaning it can form 4 covalent bonds with other atoms.
• This property allows carbon to form complex organic compounds.
• It is the backbone of all organic molecules.

Additional information:

Examples of Carbon Compounds (5):

1. Methane (CH₄)
2. Ethane (C₂H₆)
3. Glucose (C₆H₁₂O₆)
4. Ethanol (C₂H₅OH)
5. Carbon dioxide (CO₂)

Last verified on 19-01-2026

Explanation

Metalloids have properties of both metals and non-metals.

They can conduct electricity better than non-metals but worse than metals.

Examples include silicon, boron, and germanium.

Metalloids are widely used in semiconductors and electronics.

Their mixed properties make them important in modern technology.