Chemistry Paper 1 (2008)


October 17, 2015 Facebook Twitter LinkedIn Google+ KCSE Exams


KCSE PAST EXAM – Chemistry Paper 1 (2008)

 Question 1

This question consist of two parts A and B.

Attempt both parts.

PART A

You are provided with the following;

  • –          cooper wire
  • –          A retort stand, boss and clamp
  • –          an optical pin mounted on a cork
  • –          A stop watch
  • –          Wire cutters (to be shared)
  • –          a metre rule or half metre rule.

proceed as follows;

(a)  clamp the cork so that the optical pin is horizontal.hang the cooper wire from the pin

by the loops as shown in figure 1.ensure the ire is straight and the length X between

the lower tip and the optical pin is 32cm.if the length exceed 32cm reduced by cutting

at the lower tip using the wire cutters provided.

(b)  displace the lower tip of the wire slightly in a plain perpendicular to the optical pin and then

release it.measure the time t for 20 oscillation of the wire and record the value in table 1.

(c)  repeate the procedure in (b) above for other values of x shown in the table.(Not that each

length X is obtained by cutting off an appropriate length from the lower tip of the wire.For

example to get X = 28cm cut off 4cm from the lower end).complete the table.

 

(d)  Plot a graph of T2 (y-axis) against X. (5 marks)

(e)  (i)  Determine the slope, S , of the graph. (3 marks)

(ii)  obtain the value of K in the equation

   (2 marks)

PART B

You are provided with the followings:

–          a cylinder container

–          some water

–          a stop watch

–          a metre rule or half metre rule

–          a boiling tube

–          some sand

–          a rubber band

Proceed as follows:

(f)  tie the rubber band round the boiling tube so that it is at the distance L= 12cm from the

bottom of the tube (see fig 2a). pour water into the cylinder container until the level is

about 2.0cm from the top of the beaker.float the boiling tube in the water in the

container.add sand gradually into the boiling tube until the tube sinks to the 12cm mark.

See the figure 2(b).

(g)  Depress the boiling tube slightly and release so that it oscillate vertically without

touching the sides of container.measure and record in table 2 the time t.

for five oscillations of the boiling tube.repeate the procedure two more times to

obtain t2 and t3 and record the values in table 2.complete the table.

(h)  Evaluate

  given that L is the length of the tube upto the rubber band in (f) and T

is the value of obtained in (g)above. (2 marks)

                                   Qustion 2

This question consists of two parts; A and B.

Attempt both parts.

PART A

You are provided with the following:

–          a triangular glass prism

–          a piece of soft board

–          four (4) optical pins

–          a sheet of plain papers.

Proceed as follows:

(a)  Place the plain sheet of paper on the soft board.trace the trianglular outline of the prism

on the sheet of paper.remove the prism and use a ruler to extend the three sides of the

outline.see the figure 3(a).

Use a protector to measure the refracting angle R of the prism.

(b)  on the side AB of the triangular outline draw a normal at a point half-way between A

and B.this normal will be used for the rest of this experiment.

(c)  Dreaw a line at an angle i=30 degree to the normal.stick two pins P1 and P2 certicaly on this

line.see figure 3(a). (5 marks)

(d)  Place the prism accurately on the outline.by viewing through the prism from side AC

stick two other pins P3 and P4 vertically such that they are in line with the image of

pins P1 and P2.remove the prism and the pins.draw a line joining marks made by P3

and P4. extend this line to meet AC.(See the figure 3(b)).

Measure and record in table 3 the value of angle 0.

(e)  repeate the procedure in (c) and (d) above for other values of I shown in table 3.

complete the table.

N.B       The sheet of paper with the drawing must be handed in with this question

              paper.ensure you write your name and index number on the sheet of paper.

(f)  (i)  on the grid provided plot the graph of the angle of emergence E (y-axis) against

the angle of incidence i. (5 marks)

(ii)  use the graph to find I the angle of incidence at which i=E (1 mark)

(iii)  Evaluate

PART B

 

You are provided with the following:

–          a lens and a lens holder

–          a screen with cross-wires

–          a candle

–          a metre rule

Proceed as follows:

(g)  arrange the lighted candle, the lens and the screen as shown in figure 4.adjust the

position of the screen until a sharp inverted image of the candel is formed on the screen.

(i)  Measure the image distance V,

(ii)  Determine the focal length of the lens using the formula.

(h)  Now arrange the lighted candle, the screen with cross wires and the lens as shown

in the figure 5.ensure that the center of the lens.the cross wire. and the candle flame lie

on the same horizontal line.the candle flame should be placed closed to the cross-wires

for better illumination.

(i)  Adjust the postion of the lens until a sharp image of the cross-wires is formed

on the screen next to the crosswires. (Hint: You may have to rotate the lens

slightly about a vertical axis so that the image of the cross-wires falls on the

screen next to the cross-wires and not on the cross-wires).

Measure the distance d, between the lens and screen.

d =   ……………………………………………………………. cm (1 mark)

(ii)  Evaluate:

 

 

 

 

 



No votes yet.
Please wait...
Comments