Correct Answer: D. alkyne

Correct Answer: A. 0.318g

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: D. N₂

Correct Answer: B. neutral

Correct Answer: C. zinc forms a complex which is readily soluble in excess ammonia

Correct Answer: A) NH3—C—C=O

Correct Answer: B. 16.2

Explanation

(a) (i) When water does not easily form lather with soap / when water contains dissolved calcium and magnesium salts.

Water that does not easily lather with soap / Water that contains dissolved calcium and magnesium salts

(ii) Prepare soap solution

Measure volume of sample water from a burette or pipette titratewith shaking to permanent lather.

take titre value sayx cm\(^3\)

Measure same volume of boiled sample water and then titrate with shaking take titre value say y cm\(^3\)

Find ratio; \(\frac{\text{permanent}}{\text{Total}}\) = \(\frac{y}{x}\)

(iii) Waste of soap

- produces scum during washing with soap

- blockage of pipes

- scales in boilers / furring of kettles

- leads to wastage of fuel

- not suitable for tanning / laundry / textile/ paper manufacturing industries

(b) (i) NaNO\(_3\) or KNO\(_3\)

conc H\(_2\)SO\(_4\)

(ii) concentrated H\(_2\)SO\(_4\)

heat (over a sand bath)

all glass apparatus

(iii) 2HNO\(_3\) + S → H\(_2\)SO\(_4\) + 2NO

OR

6HNO\(_3\) + S → H\(_2\)SO\(_4\) + 6NO\(_2\) + 2H\(_2\)O

II. no reaction / reaction prevented / metal passive oxide formed which coats metal

(c) Zinc oxide

Lead (II) oxide

Aluminium oxide

Tin(IV)oxide

Aluminium hydroxide

Tin (II) oxide

Lead (IV) oxide

Beryllium oxide

Correct Answer: A. charge on electron