2000 - WAEC Chemistry Past Questions and Answers - page 4
31
Which of the following procedures is suitable for identifying the food colouring added to a pastry sample?
A
carry out some food tests
B
examine the pastry sample under a microscope
C
Do a chromotogram of the colouring extract
D
determine the molar mass of the colouring
correct option: c
Users' Answers & Comments32
C8H18 will undergo the following reactions except
A
cracking
B
combustion
C
substitution
D
addition
correct option: d
Users' Answers & Comments33
Which of the following is correct about both compounds show below? CH3CH 2CH2OH;CH 3
CH 2CH(OH)CH3
CH 2CH(OH)CH3
A
They have identical physical properties
B
They are structural isomers
C
Their general molecular formula is the same
D
They are oxidized to alkanones
correct option: c
Users' Answers & Comments34
Which of the following needs to be hydrolysed before it shows reducing property?
A
Glucose
B
Maltose
C
Sucrose
D
Fructose
correct option: c
Users' Answers & Comments35
Two-organic substances are labelled K and L if K gave a blue-black colour with iodine solution and L gave a deep red precipitate with Million's reagent, it can be concluded that
A
K is a carbhydrate and L is a protein
B
K is alkaline and L is acidic
C
K is unsaturated and L is a reducing sugar
D
K is a reducing agent and L is an amino acid
correct option: a
Users' Answers & Comments36
A colourless, odourless liquid T, gives effervesce with sodium trioxocarbonate (IV) and a white precipitate with silver trioxonitrate (V) solution T is mose probably
A
sodium chloride soluttion
B
barium chloride solution
C
dilute trioxonitrate (V) acid
D
dilute hydroxide is unstable
correct option: c
Users' Answers & Comments37
When sodium hydroxide solution is added to a solution of zinc salt, the white precipitate fromed redissolves in excess sodium hydroxide because
A
sodium is more reactive than zinc
B
sodium hydroxide is a strong alkali
C
zinc hydroxide is amphoteric
D
zinc hydroxide is unstable
correct option: c
Users' Answers & Comments38
Which of the following on burning in air contributes to acid rain?
A
Sulphur
B
Magnesium
C
Aluminium
D
Zinc
correct option: a
Users' Answers & Comments39
If 20 cm3 of distilled water is added to 80 cm3 of 0.50 mol dm-3 hydrochloric acid, the concentration of the acid will change to
A
20 mol dm-3
B
0.40 mol dm-3
C
2.00 mol dm-3
D
5.00 mol dm -3
correct option: b
From M1V1 = M 2
V2; m 1 = 0.50 mol dm-3; m2 = ?; v1 = 80cm 3 = 100cm3
:. m2 = m1v2/v2 = 0.50 x 80/100 = 0.40 mol dm-3
Users' Answers & CommentsV2; m 1 = 0.50 mol dm-3; m2 = ?; v1 = 80cm 3 = 100cm3
:. m2 = m1v2/v2 = 0.50 x 80/100 = 0.40 mol dm-3
40
Biotechnology is applied in the following except
A
baking industry
B
wine production
C
production of antibiotics
D
manufacture of soap
correct option: d
Users' Answers & Comments