Section 1: Additional Questions for students to attempt
Multiple Choice
1.
Naturally occurring silicon is a mixture of three isotopes,
28
Si, 29 Si and
30
Si.
The relative atomic mass of silicon is 28.109.
What could be the relative abundance of each of the three isotopes?
(November 2007 ‘A’ Levels Paper 1 Q1)
A
B
C
D
2.
91.1% 28Si, 7.9% 29Si and 1.0% 30Si
92.2% 28Si, 4.7% 29Si and 3.1% 30Si
95.0% 28Si, 3.2% 29Si and 1.8% 30Si
96.3% 28Si, 0.3% 29Si and 3.4% 30Si
Ethanedioate ions, C2O42-, are oxidised by hot acidified, aqueous potassium manganate (VII) according to the following equation.
2MnO42-(aq) + 5C2O42-(aq) + 16H+(aq) 2Mn2+(aq) + 10CO2(g) +8H2O(l)
What volume 0f 0.020 mol dm-3 potassium manganate (VII) is required to oxidise completely 1.0 x 10-3 mol of the salt KHC2O4.H2C2O4?
(November 2009 ‘A’ Levels Paper 1 Question 2)
A
3.
20 cm3
B
40 cm3
C
50 cm3
D
125 cm3
A small peptide X is hydrolysed according to the following reaction.
X
What is the Mr of X?
(November 2009 ‘A’ Levels Paper 1 Question 30)
A
359
B
377
C
431
D
449
Structured
1.
Calcium sulphate occurs naturally as the dehydrate gypsum, CaSO4.2H2O.
When heated to 160ºC, gypsum loses some of its water to give plaster of
Paris, which is used for making fine plaster casts and for setting broken limbs. During the heating process, 100 g of gypsum loses 15.7 g of water. Calculate the formula of plaster of Paris.
(November 2002 ‘A’ Levels Paper 3 Question 4)
2.
When aqueous ammonia is added to an aqueous solution of an aluminium salt, a precipitate of ‘aluminium hydroxide’ is formed as an amorphous gelatinous mass. When dried, this precipitate forms a white crystalline compound called boehmite.
