Explanation

• James Chadwick is known for his discovery of the neutron in 1932.

Additional information:

• Proton: Protons were discovered by Ernest Rutherford, before neutrons.
• Electron: Electrons were discovered by J.J. Thomson, much earlier than protons or neutrons.
• Positron: A positron is the antiparticle of an electron, and it was discovered by Carl Anderson in 1932.

Last verified on 29-10-2026

Explanation

At STP, 1 mole of any gas = 22.414 dm³ = 6.022 × 10²³ molecules.

64g of O₂ = 64/32 = 2 mol = 2 × 6.022 × 10²³ = 1.204 × 10²⁴ molecules

Last verified on 29-10-2026

Explanation

• Stoicheion is a Greek word meaning element.
• The word is associated with the basic constituents of matter in ancient Greek philosophy.
• The word chemistry has a different origin, while the term element refers to a pure substance made of only one type of atom.

Last verified on 29-10-2026

Explanation

The balanced chemical equation is: 4Al + 3O₂ → 2Al₂O₃.

Molar mass of Al = 27 g/mol, so 27 g of Al = 1 mole.

According to the equation, 4 moles of Al react with 3 moles of O₂.

Therefore, 1 mole of Al requires ¾ mole of O₂.

Mass of O₂ = ¾ × 32 = 24 g.

Last verified on 29-10-2026

Explanation

• Foam is a colloid in which gas is dispersed in a liquid.
• Examples include soap foam and whipped cream.

Last verified on 29-10-2026