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Form 4 Chemistry Mid Term 1 Examination 2023

Class: Form 4

Subject: Chemistry

Level: High School

Exam Category: Form 4 Mid Term Exams

Document Type: Pdf

    

Views: 1401     Downloads: 149

Exam Summary

NAME …………………………………………………………………ADM No……………… CLASS……..

233
CHEMISTRY
(THEORY)
TIME: 2 HOURS

MID-TERM 1EXAMS – 2023
1. A student set up the following apparatus in order to determine percentage of Oxygen by volume of air.
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i. State and explain the observations made on the moist iron wool at the end of theexperiment (after a week). (1mk)
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ii. Give the expression of the percentage of oxygen by volume in the air in terms of the letter X, W,YandZinthediagram. (1mk)
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iii. Write the formula of substance T. (1mk)
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2. The paper chromatography below shows the identification of unknown metal ion E and F. Thereference ions are K,L,M and N are shown. The experiment was done in ascending method.
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(i) Name the ions in the mixture E. (1mk)
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(ii) Mixture F contains all the three ions. On the diagram show the chromatogram of F. (1mk)

(iii) Comment on the ion N in the diagram. (1mk)
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4. The following data gives pH values of solutions A, B and C.
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a) Which metal is likely to be magnesium? (1mk)
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b) Which metal may be used as a cooking pot? (1mk)
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c) Arrange the metals in order of reacting starting with the most reactive. (1mk)
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6. An element Q has atomic number 3, relative atomic mass 6.94 and consists of two isotopes of mass 6.0 and 7.0.
(i) What is the mass number of the more abundant isotope of Q? Give a reason for your answer. (1mk)
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(ii) Calculate the percentage abundant of the isotope which is more abundant. (2mks)
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8. An element Y has the electronic configuration of 2.8.5.
(a) Write the formula of the most stable anion formed when element Y ionizes. (1mk)
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(b) Write the formula of the compound formed by X and Y if the ion of x is represented as X2+ (1mk)
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(c) Explain the difference between the atomic radius of element Y and its ionic radius. (1mk)
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9. Using dots(.) and crosses (x) diagram show he bonding in the following compounds.
(a) Lithium oxide ( Li= 3, O=8). (1mk)

(b) Carbon(II) oxide ( C =6, O=8) (1mk)

4. Starting with zinc sulphate solution describe how a sample of zinc oxide can be obtained (3mks)
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10. The diagram below shows a set up that can be used for preparation of solid T in the laboratory.
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11. Below is a table showing elements in group II of the periodic table. Study it and answer the questions that below.
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14. The melting point of phosphorus trichloride is 90°C while that of magnesium chloride in 715°C in
terms of structures and bonding explain the differences in their melting point. (3mks)
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15. (a) Name one property of Neon that makes it possible to be used in electric lamps. (1mk)
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(b) Name any other use of Argon other than in electric lamps. (1mk)
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16. A compound with molecular C2 H6O reacts with sodium metal forming a basic solution.
(a) Draw and name the structure of the compound. (2mks)

(b) To which homologous series does the compound C2 H6 O belong? (1mk)
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17. a) In the fractional distillation of liquid air explain how each of the following components
are removed prior to liquifaction of air.
i) Dust particles (1mk)
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ii) Carbon (iv) Oxide (1mk)
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iii) Water Vapour (1mk)
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18. A sample of water is suspected to contain Zinc ions and chloride ions. Give a test on how you can identify the presence of the ions. (3mks)
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19. The mass of a solution of salt of sodium chloride is 70.0g. This solution has 10.0g of sodium chloride dissolved in it. The solubility of this salt 30g/l00g of water at 25°C. 6.0g of sodium chloride salt are added to the solution at 25°C. How much sodium chloride will remain undissolved? (3mks)

20. When 23 .2g of a hydrocarbon whose empirical formula is C2H5 was allowed to evaporate it occupied 9.6dm3 at R.T.P what is its molecular formula? (molar gas volume= 24dm3 at R.T.P) (3mks)
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