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The furring of kettles or boilers - this is as a result of the decomposition of \(Ca(HCO_3)_2\) into \(CaCO_3\), and this\(CaCO_3\) coats the inside of a kettle or boiler used in heating water containing dissolved \(Ca(HCO_3)_2\). When a kettle has been used to boil temporary hard water for quite some time, the inner surfaces become coated with a white fur-like layer. This layer (furring of the kettle) is due to the gradual deposition of calcium trioxocarbonate(IV), from the decomposition of Calcium hydrogentrioxocarbonate (IV).

Zn\(^{2+}\) + 2e\(^-\) → Zn 2F will be liberated 65g of Zn, if 0.65gm of Zn is liberated, the quantity of electricity used X = (0.65/65) X 2 = 0.02F ∴ Hg\(^{2+}\) + 2e\(^-\) → Hg i.e 2F → 201gm of Hg ∴ 0.02 will liberated Y = \(\frac{0.02}{2}\) X 201 = 2.01g

The dehydration of tertiary alcohols is relatively simple and can be achieved by heating the alcohol to a high temperature or using a catalyst. The dehydrated product is a mixture of alkenes, with or without carbocation rearrangement. Recall that dehydration process involves removal of a molecule of water. As a result,the OH in the tertiary alcohol will combine with one atom of H from the CH\(_3\) attached to the C atom carrying the OH group, to form water, thereby introducing a C=C. The product of dehydrating a tertiary alcohol is an alkene. Therefore, option D is the correct answer.

In Δ PQS, ∠PSQ = X(base ∠s of isoc Δ PQS) In Δ QRS, ∠RQS = ∠PSQ + X(Extr ∠ = sum of two intr. opp ∠s) ∴ ∠RQS = X + X = 2X Also ∠QRS = 2X(base ∠s of isoc Δ QRS in Δ PRS, 72 = ∠RPS + ∠PRS(Extr, ∠ = sum of two intr. opp ∠s) ∴ 72 = x + 2x 72 = 3x x = 72/3 x = 24o

r = \(\frac{2}{3}\)R ∴R = \(\frac{3}{3}\)R Area of small circle = πr2 = π(\(\frac{2R}{3}\))2 Area of the big circle πr2 = π\(\frac{(3R)^2}{3}\) Area of shaded portion = π(\(\frac{3R}{3}\))2 - π(\(\frac{2R}{3}\))2 = π[(\(\frac{3R}{3}\))2 - (\(\frac{2R}{3}\))2] = π[(\(\frac{3R}{3}) + (\frac{2R}{3}) - (\frac{3R}{3}\)) - (\(\frac{2R}{3}\))] = π[(\(\frac{5R}{3}\)) (\(\frac{R}{3}\))] = π x \(\frac{5R}{3}\) x \(\frac{R}{3}\) = 5/9πR2

Volume of cylinder = πr2h = π x 32 x 20 = π x 9 x 20 = 180 πcm3 Volume of hemisphere = 2/3πr3 = 2/3 x π x 32 = 2 x π x 32 = 2 x π x 9 = 18π = Volume of the solid = 180π x 18π = 198πcm3

∠PQR = 180 - 128 (∠s on a straight line) = 52o ∠QPR + 76 + 52 = 180(extr ∠ = sum of intr. opp ∠s) ∠QPR + 128 = 180 ∠QPR = 180 - 128 = 52o ∴ΔPQR is an isosceles triangle

20 + X + 50 + 40 + 2X + 60 = 260 3X + 170 = 260 3X = 260 - 170 3x = 90 x = 30 Absent for at least 4 days 4 5 6 40 2x 60 i.e 40 + 2x + 60 = 40 + (2 x 30) + 60 = 40 + 60 + 60 = 160

No expanded working has been attached for this question yet. The verified answer is Option C.

No expanded working has been attached for this question yet. The verified answer is Option A.

No expanded working has been attached for this question yet. The verified answer is Option D.

The word “adroit” means skilful, clever, or tactful in handling a situation. The opposite of this would be someone who handles matters badly or awkwardly.

No expanded working has been attached for this question yet. The verified answer is Option B.

The word "notorious" means being famous or well known for something bad or negative. The opposite of this would be "renowned", which means being famous or well known for something good or positive.

No expanded working has been attached for this question yet. The verified answer is Option D.