Explanation

• Viscosity is a measure of a liquid’s resistance to flow due to internal friction between its layers.
• Liquids with high viscosity, such as honey, flow more slowly than liquids with low viscosity, such as water.

Last verified on 29-10-2026

Explanation

• The molar mass of carbon is approximately 12 g/mol, so 12 g of carbon contains 1 mole of atoms.
• The molar mass of magnesium is approximately 24 g/mol, so 24 g of magnesium also contains 1 mole of atoms.
• One mole of any element contains Avogadro's number, 6.022 x 10^23, of atoms.
• Therefore, both samples contain the same number of atoms.

Last verified on 29-10-2026

Explanation

• The value of Planck's constant is 6.63 × 10⁻³⁴ Js.
• This constant is fundamental in quantum mechanics.
• It relating the energy of a photon to its frequency.

Last verified on 29-10-2026

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

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