Explanation

(a) Avogadro's law states that equal volumes of all gases at the same temperature and pressure contain the same number of molecules.

(b)(i) Gaseous state (ii) Solid state (iii) Gaseous state.

Correct Answer: C. Zn²⁺

Correct Answer: B) the Avogadro's number

Correct Answer: A. Sublimation

Explanation

(a)(i) Is the energy required to remove one mole of an electron from a gaseous atom.

OR

Is the minimum energy required to convert one mole of a gas of atom into one mole of a gaseous plus 1 ions

(ii) \(_{4}\)Be: Is\(^{2}\) 2s\(^{2}\)

\(_{5}\)B :Is\(^{2}\) 2s\(^{2}\) 2p\(^{1}\)

The electron to be removed from Be is in the 2s orbital which is closer to the nucleus, nuclear attraction is greater hence first ionization energy is greater but the electron to be removed from B is in the 2p orbital which is farther away from the nucleus, hence nuclear attraction is weaker hence first ionization energy is smaller.

OR

2p has less energy than 2s

So it is easier to remove an electron from 2p as the nuclear charge is weaker in 2p because 2p is further away from the nucleus. Hence, first ionization energy is small.

(b) Q - It

Q = 0.12 x 500

= 60 C

96500 = 1F

= 60 C liberates 0.015g

\(\therefore\) 96500 will liberate \(\frac{96500}{60}\) x 0.015

= 24 g

n((T\(_{1}\)) = \(\frac{m}{M}\)

= \(\frac{24}{48}\) = 0.5mol

1F = 0.5mol

2F = 1mol

hence charge = +2

Alternative A

Q = lt

= 0.12 x 500

= 60 C

0.015 g of Ti is deposited by 60 C .

\(\therefore\) 48 g will be deposited by = \(\frac{60}{0.015}\) x 45

= 1920000

96500 C\(\equiv\) i mole of electron

\(\therefore\) 192000 C \(\frac{1}{96500}\) x 192

= 1.989

\(\approx\) 2.0 moles of electron

\(\therefore\) charge on Ti ion is +2

Alternate B

\(\frac{m}{M} = \frac{It}{nF}\)

n = \(\frac{Mlt}{mF}\)

= \(\frac{48 \times 0.12 \times 500}{0.015 \times 96500}\)

= 1.989 \(\equiv\) 2

\(\therefore\) Change on Ti ion is +2

(c)(i) Alumina (Al\(_{2}\)\(_{3}\)) mixed with molten cryolite (Na\(_{3}\)AIF\(_{6}\))

(i) - abundant deposits of bauxite

- cheap source of electricity

(d)(i) Is the ability of a substance to be attracted strongly into a magnetic field.

(ii) I. \(_{24}\)Cr\(^{2+}\) - Is\(^{2}\) 2P\(^{6}\) 3S\(^{2}\) 3P\(^{6}\) 3d\(^{4}\)

unpaired electrons = 4

\(_{24}\)Cr\(^{6}\) - Is\(^{2}\) 2s\(^{2}\) 2p\(^{6}\) 3s\(^{2}\) 3d\(^{6}\)

unpaired electrons = 0

(II) \(_{24}\)Cr\(^{2+}\)

III. The greater the number of unpaired electrons in the 3d - orbital, the| greater-the paramagnetism.

Correct Answer: B. Double decomposition

Correct Answer: D. I, III and IV only

Correct Answer: D) But-1-yne

Explanation

(a)(i) The boiling point of the substance. The density is a property used to measure the purity of a substance.

(ii) The preparation of sodium chloride by neutralization reaction is the reaction between dilute hydrochloric acid and sodium hydroxide

i.e NaOH\(_{(aq)}\) + HCI\(_{(aq)}\) \(\to\) NaCI\(_{(aq)}\) + H\(_2\)O\(_{(l)}\)

Sodiumchloride

The salt is then crystallised out of the water and allowed to dry. The salt is white cubic crystals

(iii) A soluble salt can be prepared by the action of dilute acid on the metal. Also by double decomposition.

(b)(i) The reaction of iron in dilute copper (II) tetraoxosulphate (VI) solution produces iron (III) tetraoxosulphate (VI) and copper solid which make the solution become reddish-brown.

(ii) Aluminium hydroxide AI(OH)\(_3\) dissolves in excess sodium hydroxide to give sodium aluminate i.e NaAlO\(_2\).

(iii) The chloride gas oxidised iron (II) to iron (III) Fe\(^{3+}\)

(c)(i) 2HCI\(_{(aq)}\) + CaCO\(_{3(g)}\) —> CaCI\(_{(aq)}\) + CO\(_{2(g)}\) + H\(_2\)O\(_{(l)}\)

Marble is used to manufacture cement.

Correct Answer: B. 4.48dm³