Neutral oxides show neither basic nor acidic properties and hence do not form salts when reacted with acids or bases, e.g., carbon monoxide (CO); nitrous oxide (N₂O); nitric oxide (NO)

Fractional distillation can be used to separate ethanol and water. These two liquids are miscible with each other. This means that they can be mixed together to form a single uniform liquid. Their different boiling points allow them to be separated, as water boils at 100℃ and ethanol boils at 78℃.

When the mixture is heated, the ethanol will evaporate first. Some of the water may also evaporate with the ethanol so the temperature of the column must be controlled so that any water vapour formed condenses in the column and drops into the flask. This leads to the alcohol vaporising at the top and out into the container. This means that the ethanol produced first will be pure and should not contain any water.

Once all of the ethanol has been removed, the solution is heated further and the water will evaporate off once its boiling temperature is reached. The water obtained should be pure as all of the ethanol has been removed. This method allows both the ethanol and the water to be collected separately.

Electronic configuration = 2, 8, 8, 2

The outermost shell is the last shell hence the last shell has 2 electrons as shown in the electronic configuration.

Lime water is calcium hydroxide [Ca(OH)₂]

Carbon (IV) oxide is carbon dioxide (CO₂)

When carbon dioxide is passed through lime water, it turns milky due to formation of white precipitate in form of calcium carbonate (CaCO₃).

The reaction is shown below.

Ca(OH)₂+CO₂→CaCO₃+H₂O

Mass = 5.3 g
Molar mass = 106

Mole = $\frac{5.3}{106}$ = 0.05 mol

Per dm³ means volume = 1 dm³

Molarity = $\frac{\mathrm{0.05\; mol}}{1{\mathrm{dm}}^3}$ = 0.05 mol dm^-3

Convert the cm³ to dm³ by dividing it by 1000

100 cm³ = 0.1 dm³

Volume = 0.1 dm³

Molarity = 0.5 moldm^-3

Molar mass = 58.5

0.5 = $\frac{\mathrm{Mass}}{\mathrm{58.5\; x\; 0.1}}$

Mass = 0.5 x 58.5 x 0.1 g = 2.93 g

Method I

Using the formula

Mole = 0.001 mol

Avogadro's constant = 6.02 x 10²³ per mol

Number of atoms = 6.02 x 10²³ x 0.001

Number of atoms = 6.02 x 10²⁰

Method II

Using proportionality

1 mole contains 6.02 x 10²³ atoms

0.001 mol contains 6.02 x 10²³ x 0.001 atoms

0.001 mol contains 6.02 x 10²⁰ atoms

Example of a trioxocarbonate (IV) salt is calcium carbonate.

The reaction with hydrochloric acid is shown below:

CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O

Note: CO₂ is carbon (IV) oxide.