Consider the following molecules and answer the questions that follow.
A.NH3
B.CO2
C.C2H2
D.H20
E.BH3
Which molecule:
1.1.1 Contains a triple bond? [1]
1.2 Is trigonal planar? [1]
1.3 Is angular in shape and contains a centre atom with two lone pairs? [1]
2.Which TWO molecules can form a dative covalent bond with a hydrogen ion? [2]
1. Draw a Lewis structure of the CO2 molecule. [2]
2 Briefly explain why the bonds shown in your answer to
QUESTION .1 are considered to be “polar covalent”. Refer to the difference in electronegativity of the atoms involved. [4]
[11]
During a mountain climbing exercise, Ferial, mass 50 kg, is suspended from an inelastic piece of nylon rope, fixed to a vertical cliff at X on the cliff. She pushes her legs against the cliff so that they make an angle of 45° with the cliff, as indicated in figure. The angle that the rope makes with the cliff is 20°.
Point Y is in equilibrium.
2.1 Explain what is meant by Point Y is in equilibrium. [1]
2.2 Draw a FORCE DIAGRAM showing all the forces acting on point Y. [3]
2.3 Determine by means of ACCURATE CONSTRUCTION and MEASUREMENT.
(use the scale 10 mm: 50 N and indicate at least TWO angles):
2.3.1 The magnitude of the force which the rope exerts on her.[4] 2.3.2 The magnitude of the force exerted by her legs. [4]
[12]
A 6 kg block on a horizontal rough surface is joined to a 2 kg block by a light, inelastic string running over a frictionless pulley. The frictional force between the 6 kg block and the table is 11,76 N. A downwards force of 2 N is applied to the 2 kg block as indicated in the diagram below.
1. State Newton’s Second Law of motion in words. (2)
2.Draw a free-body diagram showing ALL the forces acting on the 6 kg block.(4)
3.Calculate:
3.1. The magnitude of the acceleration of the 6 kg block. (5)
3.2.The magnitude of the tension (T) in the string connecting the two blocks.(2)
4. The rough surface is replaced by a smooth frictionless surface.
How will this change affect the answer in QUESTION 3.1? Write only INCREASES, DECREASES or REMAINS THE SAME. (1)[14]
Physical sciences break 1.0 
1.1 c
1.2 A
1.3 A
2. E
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1.1 C
1.2. E
1.3 B
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