Correct Answer: C. Ummul kitab

Correct Answer: B. haematite

Explanation

Cast iron + haematite = wrought iron.

Correct Answer: C. rainfall

Explanation

(a) Price elasticity of demand means the degree of responsiveness of demand to little changes in prices of goods and services.

Formula =Percentage change in demandOR

Percentage change in price

dp x p

dq x q

(b)(i) ED=Percentage change in demand OR

Percentage change in price

dp x p

dq x q

When price rises from N10 to N11

Percentage change in demand = 1000 - 150 = 50

\(\frac{50}{1000} \times \frac{100}{1}\) = 5%

Percentage change in price = N11 - N10 = N 1

\(\frac{1}{10} \times \frac{100}{1}\)= 0.5OR

ED = changes in Q X P

change in P Qd

= \((\frac{}{1} \times \frac{10}{1000}\) = 0.5

(ii) Demand is inelastic since elasticity is less than one

(iii) Elasticity of supply =Percentage change in supply

Percentage change in demand

Percentage change in supply = 1000 - 850 = 150

= \(\frac{150}{1000} \times \frac{100}{1}\) = 15%

OR

ED = change in Qs X P = \(\frac{150}{1} \times \frac{10}{1000}\) =1.5

change in P Qs

(iv) Elasticity of supply is elastic because the value is greater than one.

Correct Answer: B. thrift society

Explanation

(a)(i) Water is a universal solvent because it can dissolve many substances. water is polar and as a result, it can dissolve ionic solutes as well as partially ionic/polar covalent substances

(ii) Add water to anhydrous copper

(II) tetraoxosulphate (VI) salt, colour changes from white to blue. OR Add water to anhydrous cobalt

(II) ch!oric!e, colour changes from blue to pink.

(b)(i) I. OH\(^-{_(aq)}\) \(\to\) 2H\(_2\)O\(^-{_(l)}\) + O\(_{2(g)}\) + 4e\(^-\)

II. 2H\(^+_{(aq)}\) + 2e\(^-\) --> H\(_{2(g)}\)

OR 4H\(^+_{(aq)}\) + 4e\(^-\) --> 2H\(_{2(g)}\)

Ill. 2H\(_2\)O\(_{(l)}\) -> OH\(_{2(g)}\) + O\(_{2(g)}\)

OR 4OH\(^-_{(aq)}\) + 4H\(^+_{(g)}\) --> 2H\(_2\)O\(_{(l)}\) + 2H\(_{2(g)}\) + O\(_{2(g)}\)

(ii) Quantity of electricity = 1 x t = 1.25 x 40 x 60 = 3000C

For 1 mole of O\(_2\) formed at the anode, 4e\(^-\) are generated Volume of O\(_2\) formed by 3000C = \(\frac{3000}{96500}\) x \(\frac{1}{4}\) mole O\(_2\)

= 7.77 x 10\(^{-3}\) moles

1 mole O\(_2\) occupies 22.4 dm\(^{3}\) at s.t.p. mole of O\(_2\) = 7.77 x 10\(^{-3}\) x 22.4 dm\(^{3}\) = 0.174dm\(^{3}\)/174 cm\(^{3}\)

OR From the equation at anode; 4 x 96500C = 22.4 dm\(^{3}\)

3000C = \(\frac{22.4 \times 3000}{4 \times 96500}\)

= 0.174dm\(^{3}\) / 174 cm\(^{3}\)

(c)(i) 2Au\(_{(s)}\) + 3Cl\(_{2(g)}\) \(\to\) 2AuCI\(_{3(s)}\)

(ii) Amount of Au= \(\frac{1.2}{197}\) = 0.00634 mole

Amount of Cl\(_2\) = \(\frac{1.744}{71}\) = 0.0246 mole.

From equation: 2 moles of Au = 3 moles of Cl\(_{(2)}\)

.-. 0.00634 mole of Au = \(\frac{0.00634 \times 3}{2}\) = 0.00951 mole

Amount of CI\(_2\) available = 0.0246 mole but amount required by all the Au for the reaction = 0.00951

CI\(_2\) is in excess.

(iii) Excess amount of CI\(_2\) = amount available - amount used = 0.0246 - 0.00951 = 0.015 mole.

Correct Answer: C. trade and aids to trade

Correct Answer: D. Mauritania

Correct Answer: A. acquired characteristics

Explanation

Acquired traits include things such as calluses on fingers, larger muscle size from exercise or from avoiding predators.

Correct Answer: D. 9/30;net 3