CONTEST 24

ROUND 1
1. State one similarity each between a bulb and a Rhizome

ANSWERS:
a. They both have scale leaves
b. They both have buds
c. They both have adventitious roots
d. They both have food reserves
e. Name the region of an optical fibre in which light is confined.
f.
PREAMBLE: The specific heat capacity of a substance is 200 J kg-1 K-1.

2. What is the heat capacity of 60 kg of the substance?

ANSWER: 12 kJ/K = 12 000 J/K

3. How much thermal energy is required to increase the temperature of 1 kg of the substance by 20 K?
ANSWER: 4000 J = 4 kJ
4. What mass of the substance has a heat capacity of 50 J/K?
ANSWER: 0.25 kg = 250 g

PREAMBLE: The numbers are given to the accuracy stated. State the maximum possible value and the
minimum possible value

5. 270 (nearest ten)

ANSWER: max = 275, min = 265
6. 240 (2 significant figures)
ANSWER: max = 245, min = 235
7. 276 (nearest whole number)
ANSWER: max = 276.5, min = 275.5
8. The standard electrode potentials of the half cells, Cr3+/Cr and Cd2+/Cd are -0.74 and -0.40 respectively.
State the expected observation when a chromium rod is immersed in a solution of Cd 2+.
ANSWER: Cd2+ will be reduced to Cd and deposited on the Cr rod. Some of the Cr will dissolve /
or get oxidised to Cr3+ and go into solution.
9. Consider the following half cells with their standard electrode potentials: Cu +/Cu, 0.52v; Cu2+/Cu, 0.34v and
I2/I-/Pt, 0.53v. Which reaction, iodine oxidising copper to copper (I) or iodine oxidising copper to copper (II)
will occur readily?
ANSWER: I2 oxidising Cu to Cu2+

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10. The following two half cells, Ni2+/Ni and Fe3+/Fe2+/Pt have electrode potentials 0.23v and 0.77v respectively.
Give the balanced equation for the reaction of a cell that can be created from the two half cells.
ANSWER: Ni + 2Fe3+ → Ni2+ + 2Fe2+
11. Explain why diffusion can transport essential nutrients to all parts of a unicellular organism
ANSWER: The unicellular organisms possess a large surface area to volume ratio

12. Explain why the response in a simple reflex action is always the same for any given stimulus.
ANSWER: The impulse travels along the same nervous pathway.

13. What is nitrogen fixation?

ANSWER: The process by which microorganisms convert atmospheric nitrogen into nitrogenous
compounds.
14. Rank the following in order of increasing energy: ultraviolet radiation, microwave radiation, gamma radiation.
ANSWER: Microwave, ultraviolet, gamma radiation
15. Rank the following in order of increasing wavelength: infrared radiation, blue light, x-rays.
ANSWER: x-rays, blue light, infrared radiation
16. Rank the following in order of increasing frequency: red light, radio waves, ultraviolet radiation.
ANSWER: Radio waves, red light, ultraviolet radiation
PREAMBLE: Solve the equation for x

17. 5x = 3
log 3 log 3
ANSWER: x= [ xlog5=log 3 , x= ]
log 5 log 5
18. 7x = 10
log 10 log 10
ANSWER: x= [ xlog7=log 10 , x= ]
log 7 log 7
19. 32x = 5

ANSWER: x= (
1 log5
2 log3 ) [2 xlog5=log 3 , x =log ( )
1 log 3
2 log 5
]

20. There are two types of nuclear reactions. What are they?
ANSWER: (1) Radioactive decay (nucleus spontaneously disintegrates giving off radiation)
(2) Nuclear bombardment reaction (nucleus is bombarded by a nucleus or a nuclear particle)
21. Why is the neutron the favoured nuclear particle for nuclear bombardment?
ANSWER: Its penetration of the atom is unhindered since it has no charge.
22. Some radioactive nuclei decay by β emission, what is this process equivalent to?
ANSWER: Equivalent to conversion of a neutron to a proton in the nucleus.
23. Which tissues provide nutrient molecules for growing plant embryos before the true leaves begin
photosynthesizing?
ANSWER: cotyledon and endosperm

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 24. In which organelles are thylakoids and grana found?
ANSWER: chloroplasts
25. What name is given to the ring of waxy material that borders the endodermal cells in plants?
ANSWER: Casparian strip
26. Two massive bodies attract each other with a gravitational force of 2 mN when the distance between them is 5 m.
What is the force of attraction when the distance between them is 10 m?
ANSWER: 0.5 mN
27. Two massive bodies attract each other with a gravitational force of 0.4 mN when the distance between them is 50 m.
What is the force of attraction when the distance between them is 25 m?
ANSWER: 1.6 mN
28. Two objects each with mass 10 000 kg attract each other with a gravitational force of 0.2 mN. What is the force of
attraction when the mass of one of the objects is increased to 20 000 kg?
ANSWER: 0.4 mN
PREAMBLE: Find the next term in the sequence
1 1 1 1
29. , , , ,…
3 6 12 24
1
ANSWER:
48
2 3 4
30. 1, , , ,…
3 9 27
ANSWER: 5/81
1 2 3 4
31. , , , ,…
2 3 4 5
5
ANSWER:
6
32. What is pOH of a solution?
ANSWER: It is –log10 [OH] or It is a measure of hydroxide ion concentration of a solution.
33. State if the pH of beer is above or below 7.
ANSWER: pH of beer is below 7, (4.0 – 4.5)
34. What is the pH range of the gastric juice in the stomach?
ANSWER: pH = 1.0 – 3.0

PROBLEM OF THE DAY

Working together, it takes 2 painters 2 days to paint a house. Working lone, one painter will take

twice as long as the other painter to paint the same house. How long will each painter take to paint

the house working alone?

SOLUTION

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 Painter Time Rate
1 T 1/T
2 2T 1/2T
1+2 2 ½

1/T + 1/2T = ½
3/2T = ½ , Hence
6 = 2T and T = 3

One painter takes 3 days, and the other painter takes 6 days to paint the house.

ROUND 3

TRUE OR FALSE

1. Freshly prepared Fe(OH)2 is green

ANSWER: True Turns brown on standing
2. Both ammonia solution and NaOH solution will give white, gelatinous precipitate with Al 3+
ANSWER: True
3. Fe(OH)3 is insoluble in excess NaOH solution
ANSWER: True
4. The magnitude of the linear momentum of an object is greater the greater its speed.
ANSWER: True
5. The linear momentum of an object is always in the same direction as its velocity.
ANSWER: True
6. The angular momentum of an object about a point is the moment of its linear momentum
about the point.
ANSWER: True
7. Neurons are functional units of the nervous system.
ANSWER: True
8. Sensory neurons conduct impulses away from the central nervous system.
ANSWER: False
9. Contraction of muscles makes them shorter and thicker.
ANSWER: True
10. Between 0° and 90°, the function y =sinx is increasing.
ANSWER: True
11. Between 0° and 90°, the function y = cosx is decreasing.
ANSWER: True
12. Between 0° and 90°, the function y = tanx is decreasing.

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 ANSWER: False
13. Of the three elements, sodium, magnesium, and aluminium, magnesium will have the highest
ionization energy.
ANSWER: True

14. Of the three elements, boron, carbon and nitrogen, boron will have the lowest ionization energy.
ANSWER: True
15. Of the elements nitrogen, oxygen and fluorine, nitrogen will have the lowest ionisation energy.
ANSWER: False It is oxygen.
16. The pressure at a point in a fluid is greater in the downward direction than in any other
direction because of the weight of the fluid.
ANSWER: False
17. The pressure in a liquid is greater the greater the depth below the surface of the liquid.
ANSWER: True
18. Pressure is force per unit area.
ANSWER: True
19. A higher temperature results in a greater evaporation of water from cells of leaves of plants
ANSWER: True
20. High humidity outside the leaf increases the rate of transpiration.
ANSWER: False
21. Light affects transpiration because stomata usually open in the light and close in darkness.
ANSWER: True
PREAMBLE: When a transversal cuts a pair of lines,
22. Corresponding angles are equal
ANSWER: False
23. Interior opposite angles are supplementary
ANSWER: False
24. Alternate angles are congruent.
ANSWER: False
(NB: Only when lines are parallel)

ROUND 4

RIDDLES

RIDDLE 1
1. I am a phenomenon in which electrons are emitted.

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2. I do not occur spontaneously.
3. Heat has no part with me.
4. I occur when light of appropriate wavelength is incident on a photocathode.
Who am I?

ANSWER: Photoelectric effect

RIDDLE 2

1. My nickname in English would suggest I am always sarcastic or bitter

2. I may be bitter but you dare not taste me because I can give you very nasty burns on your fingers and tongue.
3. I am not manufactured in Ghana even though my raw material is plentiful in Ghana
4. Without me how can you produce your hard soap?
Who am I?
ANSWER: Sodium hydroxide / Caustic soda

RIDDLE 3

1. I am a process for solving a quadratic equation.

2. Factorization is definitely out of the window.
3. I give rise to the almighty quadratic formular.
4. I involve finding a complete square.
Who am I?
ANSWER: Completing the square

RIDDLE 4

1. I am a type of ring
2. I am present in some plants but, completely missing in the animal world
3. I am the result of new growth in the vascular cambium of plants
4. Many trees in temperate zones make one of me each year, hence I can be used to determine the age of such
trees.
Who am I?
ANSWER: Annual Ring / Growth ring