Explanation

• The limiting reactant is the substance that is completely consumed first in a chemical reaction.
• It determines the maximum amount of product that can be formed.
• The excess reactant remains after the limiting reactant has been used up.
• The limiting reactant is identified by comparing the available amounts of reactants with their balanced chemical equation ratios.

Last verified on 29-10-2026

Explanation

• Molecular Orbital Theory (MOT) explains the paramagnetic behavior of oxygen (O₂) because it has two unpaired electrons in its antibonding π* molecular orbitals.
• Unpaired electrons are attracted to an external magnetic field, making oxygen paramagnetic.

Last verified on 29-10-2026

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