Page 284 - Chemistry

18
= Correct answer √ (whole number)
½
2. Table 1
 ½ mk each correct entry
 Penalize 1 mk if 1 d. place is not used consistently in the last row.
 Penalize ½ mark for temperature below 400c and 1000c to a maximum of 1mark.
 Penalize 1 mark if there is no trend.
(ii) Graph
 Labeling (½ mark) – Title, axes, correct units.
 Scale (½ mark) – more than on both axes.
 Plotting (1mark) – All points plotted correctly.
o Curve(1mark) – Smooth curve passing through at least 3 correctly plotted points.
(iii) ½ mark
(a) 1 mark
(b) 1mark Read from candidates graph and credited only if within  0.1 the S.V
(c) 1 mark
3. (a)
Observations Inferences
- Black residue √ ½
½
- Colourless solution as filtrate √ X
(b)
2+
½
½
- Blue solution formed√ CU may be present √
½
½
- No effervescence √ HCO 3 , CO 3 √ absent the two
(c )
- Blue ppt √ ½ CU may be present √
2+
½
½
- Insoluble in excess √
(d)
2+
- Blue ppt√ CU Present
½
- Soluble to give a deep blue solution√
½
2+

(e) – No white ppt √ Ag+ pb absent ( for two) CO 3 HCO 3
1
2-
-
-
(f) – White ppt √ Cl , SO 4 may be present √
½
1
2-
(g) – White ppt √ SO 4 present √
½
½

2+
3+
(h) – White ppt √ ½ Zn, Al may be present
- Soluble in excess √
½
2+
(i) – White ppt √ ½ Zn Present.
- Soluble in excess

UGENYA – UGUNJA DISTRICT

Q.1. a) Table 1
I II III
Final burette reading 20.0 40.0 20.0
3
(cm )
Initial burette reading 0.0 20.0 0.0
3
(cm )
Volume of solution M 20.0 20.0 20.0
3
used (cm )
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