Marks distributed as follows

a) COMPLETE TABLE (CT) (5marks)

(Complete the table with 10 readings.)

PENALTIES/CONDITIONS

i. Penalize â…Ÿ2marks for each space not filled (TICK OR PUT CROSS)

ii. Reject fractions for â…Ÿtime and award a maximum of 2â…Ÿ2marks for the time column (table)

iii. If FRACTIONS appear followed by an extra column of decimals IGNORE the fraction column and award accordingly.

iv. Penalize ⅟2mark each for wrong arithmetic in the reciprocals not within an error of ±2units in the third decimal place (d.p) e.g.0.054, 0.056, and 0.058. v. Accept reciprocals expressed in standard form or in the power of tens. E.g. 5.4 × 10-2.

vi. ACCEPT reciprocals given to at least 3d.ps; otherwise penalize â…Ÿ2mark each to a maximum of 1mark for rounding off to 2d.ps. UNLESS the figure divides out exactly. E.g. 0.067 rounded to 0.07 is wrong.

vii. PENALISE ⅟2marks for any TIME reading that is less than Five (<5) OR greater than 120 (5≤ t ≤120). In the time column BUT credit the reciprocals columns accordingly.

viii. Penalize â…Ÿ2marks for each for entry not in SECONDS in the time column.

ix. Penalize â…Ÿ2 marks for each entry in fractions in the reciprocal column if the candidate enters some readings in FRACTIONS and others in decimal.

b) USE OF DECIMALS (D) (â…Ÿ2mark)
(Tied to time column only).

i. Accept whole numbers or 1d.p to 2d.p used CONSISTENTLY THROUGHOUT otherwise penalize fully.
c) ACCURACY (A) (1mark)
i. Compare the candidates FIRST READING with the school value (s.v)

ii. If the school value is with ±2 units of teacher’s value award 1mark otherwise penalize fully.
d) TREND (T) (1 mk)
(Tied to the column only)
i. Award 1mark if time is INCREASING THROUGHTOUT otherwise penalize fully.

a) TABLE I

b) GRAPH (4marks)

Marks distributed as follows;

a) SCALE (S) (â…Ÿ2mark)

i. Area covered by ACTUAL PLOTS including the origin should be half or more than half of the graph paper provided otherwise penalize fully.

ii. Scale must be consistent (linear) on both axes otherwise penalize fully.

iii. The candidates scale must accommodate all the five plots (S), otherwise penalize fully.

b) LABELLING OF AXES(A) (â…Ÿ2mark)

i. Penalize â…Ÿ2marks for wrong units.

ii. Penalize â…Ÿ2marks for INVERTED axes.

iii. ACCEPT if NO UNITS are shown both axes.

iv. Both axes MUST be correctly labeled.

v. Accept if 1unit is correctly given.

c) PLOTTING (P) (2marks)

CONDITIONS;

i. Accept 4 – 5 points correctly plotted for 2marks

ii. Accept 3 points correctly plotted for 1mark

iii. If any two (2) points correctly plotted for â…Ÿ2mark

iv. If any 1point correctly plotted for 0marks

NOTE;
i. If scale interval changes, mark the correct points within the 1st interval and award accordingly.

ii. Accept correct plots even if the axes are INVERTED OR INTERCHANGED

iii. If the points for the table are to 3 d.p or more decimal places and rounded off to two 2d.p on PLOTTING, PENALISE â…Ÿ2mark once. Otherwise accept rounding off to 3d.p.

d) LINE (L) 1mark

i. Accept a straight line passing through at least two points (2points) CORRECTLY PLOTTED and through the origin. Otherwise penalize fully. Breakdown for marks for Graph.

S - â…Ÿ2 mk

A - â…Ÿ2mk

P - â…Ÿ2mk

L - â…Ÿ2mk Total 4mark

c) i) Showing on the graph â…Ÿ2mark.
ii) Stating correct reading on graph â…Ÿt â…Ÿ2mark.
iii) Expression for t = â…Ÿcorrect reading. â…Ÿ2mark.
iv) Correct answer for t â…Ÿ2mark.
Total 2marks.
CONDITIONS;
i. Penalize â…Ÿ2mark if not shown on the graph.

ii. Award 1mark if shown on the graph BUT not stated but used correctly in the expression i.e. t = â…Ÿcorrect reading

iii. Award 1mark if not shown on the graph, not recorded, but goes straight to the expression.

iv. Accept the answer at least to 1d.p UNLESS if it works out exactly to a whole number otherwise penalize fully (â…Ÿ2mark)

v. Penalize ⅟2mark for wrong arithmetic if answer is not within ±2 units in the 1st decimal places. (d.p)

vi. Award ZERO (0) if not shown on the graph and the stated value is wrong.

vii. If the value is shown on the graph, BUT stated wrongly penalize â…Ÿ2mark for wrong reading (stating) but accept the subsequent working if done CORRECTLY and award accordingly.

viii. Penalize â…Ÿ2mark if expression is not given but the answer is correct.

d) RATE DECREASES WITH DECREASE in the concentration of hydrogen peroxide OR vice versa (2mrks) CONDITIONS;

i. The answer above must be related to either correct data from the table or correct graph.

ii. If decrease in rate is related to decrease in VOLUME of hydrogen peroxide OR VICE VERSA award 1mark.

iii. If candidates proceeds from (ii) above to relate correctly volume with. CONCETRATION of hydrogen peroxide then award fully (2marks).

iv. If CONCETRATION is related to time, only award only 1mark, BUT if the candidate proceeds to relate correctly time and rate then award another 1mark. Total for question 1(one) 15 â…Ÿ2marks.

Note; All ions must be written with correct symbols and charge. For any wrong symbol of expected ions given, penalize â…Ÿ2mark and treat it as contradictory.

b) TABLE 2

i)

NOTE;

REJECT;

Yellowish – green, greenish – yellow, bluish, pink.

ii) K+

NOTE;

i) Penalize fully if the cation is written in words

ii) Penalize fully if the cation is not correctly written e.g. k+; using small letter instead of capital.