(a) Explain briefly why \(_2^4He\) has a stable electron configuration compared to \(_4^9Be\)
(b) Consider the following elements: 1H and 3Li.
(i) State the number of electrons that an atom of each element would have after forming an ionic bond.
(ii) Give a reason for each of your answers stated in (b)(i).
(c) State two factors that should be considered when siting a chemical industry.
(d) State two advantages of using a catalyst instead of high temperatures in chemical reactions.
(e) Turpentine burns in chlorine according to the following equation:
C\(_{10}\)H\(_{16}\)\(_{(I)}\) + 8Cl\(_{2(g)}\) \(\to\) 10C\(_{(s)}\) + 16HCl\(_{(g)}\)
Calculate the mass of turpentine that would completely burn in 21.3 g of chlorine.
[Molar mass of chlorine = 71 gmol\(^{-1}\); Molar mass of Turpentine = 136 gmol\(^{-1}\)]
(f) What is cracking?
(g) State two factors that may influence the value of electron affinity.
(h) What are carbohydrates?
(i) State two differences between a simple sugar and starch.
(j) Write an equation to show the dissociation of each of the following acids:
(i) H\(_2\)CO\(_3\);
(ii) CH\(_3\)COOH.
.(a)(i) Name two gases that can be used to perform the fountain experiment. (ii) What is the aim of he fountain experiment? (iii) Describe briefly the fountain experiment.
(b)(i) Name two chemical industries. (ii) State three effects of a chemical industry on the community in which it is sited.
(c)(i) Name three products of the destructive distillation of coal. (ii) Give one use each of any two of the products named in 5(c)(1).
(d)(i) Name two substances responsible for hardness in water. (ii) State two methods for the removal of hardness in water. (iii) State two advantages of hard water.
(a) In an equilibrium reaction between gases Q and R, to form QR, the energy content of the reactants is 100 KJ and that of the product is 54 kJ. The energy content of the activated complex is 210 KJ.
(i) Draw an energy profile diagram for the reaction. (ii) Determine the: I. activation energy of the reaction il. enthalpy change ฮH of the reaction. (iii) Write a balanced equation for the reaction. (iv) Give a reason for the answer given in 3(C)(iv). (iv) State whether the reaction is exothermic or endothermic.
(b) Consider the following table:
| Element | E | F | G | H |
| Atomic number | 7 | 9 | 12 | 13 |
(i) Write the electron configuration for each of the elements. Element E, F, G, H 12 13 (ii) State: I. two elements that are metals; II. the elements(s) most likely to form an ion with a charge of +3; III. the element(s) which belong(s) to group VII. on the periodic table; IV. the formula of the compound formed between F and G. Atomic
(c) Define the term isotopy (d) Name the three building blocks of matter.
(a) In the laboratory preparation of dry chlorine gas, state the: I. reagents used; II. drying agent III. the mode of collection.
(i) Write the equation for the preparation of chlorine gas. (iii) Write an equation to show how chlorine reacts with hot concentrated NaOH.
(b)i). Name the main raw materials used for the extraction of iron in the blast furnace. (ii) Write the equations of the reactions taking place in the blast furnace.
(iii) What is the name given to the iron obtained directly from the blast furnace? (iv) State why the iron named in 4(b)(iii) have a relatively low melting point?
(c) The following equation represents one of the reaction steps involved in the contact process: 2SO\(_2\) + O\(_2\) โ 2SO\(_3\) ฮH = -395.7 kJ mo-l
(i) Why is the SO\(_3\) produced during the reaction not dissolved directly in water to form H\(_2\)SO\(_4\)? (ii) Why is the H\(_2\)SO\(_4\) regarded as a heavy chemical? (iii) State the property exhibited by tetraoxosulphate (VI) acid in each of the following reaction equations.
I. Pb(NO\(_3\))\(_2\) + H\(_2\)SO\(_4\)โ PbSO\(_4\) + 2HNO\(_3\) (d) Write a balanced chemical equation for the reaction between propanol and sodium
(a) Consider the following compounds: (i) What is the relationship between the compounds labeled A and B? (ii) Name each of compounds A and B. (iii) Will the chemical properties of compounds A and B be the same? (iv) Give the reason for the answer stated in 2(a)(ii).
(b)(i) Give two characteristic features of boiling, (ii) What would be the effect of each of the following conditions on the boiling point of water? I. Addition of crystals of sodium chloride. II. Reduction of the atmospheric pressure. (iii) State one way in which boiling differs from evaporation.
(c)(i) Differentiate between an unsaturated solution and a saturated Solution. (ii) State two ways by which a saturated solution could be made to dissolve more solute. (iii) State one factor that could affect the solubility of a solid in a liquid. (d)(i) Define the term mole .
(ii) Consider the following reaction equation: MgO + 2HCI โ MgCl\(_2\) + H\(_2\). What mass of magnesium Oxide is needed to neutralize 25.0 cm3 of 0.1 mol dm-3 hydrochloric acid? [O= 16.0; Mg = 24.0]. (e) State three physical properties of metals.
(a)(i) State Faraday’s first law of electrolysis. (ii) Distinguish between a strong electrolyte and a weak electrolyte
(b) State one chemical property of ethyne.
(c)( i) What is meant by the tern unsaturated hydrocarbon? (ii) Complete the following reaction equation: CH\(_3\) + CH\(_3\)OH-> (iii) Name the major product formed in the cation stated in 1(c)(ii).
(d) State one way by which the rate of esterification could be increased.
(e) Consider the reaction represented by the following equation: Zn + H\(_2\)SO4 โ ZnOS\(_4\) + H\(_2\) . If 3.75g of Zn dust was added to excess H\(_2\)SO\(_4\). Calculate the number of molecules of hydrogen gas produced. [ Zn = 65.0, Na = 6.02 X10\(^23\) ].
(f) State one effect of global warming.
(g) Consider the following reaction equation:
A. Pb(NO\(_3\)) +H\(_2\)S –> PbS + 2HNO\(_3\);
B. H\(_2\) + C\(_2\)H\(_4\) โ C\(_2\)H\(_6\).
C. Zn(OH)\(_2\) + 2OH โ [ Zn(OH)\(_4\) ]\(^2\).
(i) Which of the equations represent(s) redox process? (ii) State the change in Oxidation number of the species that are oxidized or reduced. (h)(i) State two of the main concepts of Bohr’s model of the atom. (ii) State the limitations of Bohr’s model. (i) List three factors that could influence the equilibrium position of a reversible reaction. (j) Calcium trioxocarbonate(iv) powder is added to separate equimolar solutions of hydrochloric acid and ethanoic acid. State one: (i) similarity in the observation in both reactions: (ii) difference in the observation in both reactions.
An example of a biodegradable pollutant is?
- A. plastic
- B. sewage
- C. carbon (II) oxide
- D. hydrogen sulphide
Calcium chloride is an ionic compound. Which of the following statements account for its ionic character?
I. Calcium has high ionization energy. II. Calcium has low ionization energy. III. Chlorine has high electron affinity. IV. Chlorine has high Ionization energy.
- A. I and Il only
- B. I, II and IV only
- C. II, IIl and IV only
- D. I, II, III and IV
Dilution factor is the?
- A. amount of distilled water that is added to the concentrated solution to dilute it
- B. Quantity of distilled water added to l dm\(^3\) of the concentrated solution to give the dilute solution
- C. number of times the volume of the concentrated solution is diluted to give the dilute solution
- D. act of diluting the concentrated solution to obtain the dilute solution
which of the following quantities is a molar quantity?
- A. Molarity
- B. Molar mass
- C. Mass concentration
- D. Molality
Which of the following processes is not exhibited by atoms in order to attain more stable electron configuration?
- A. Gaining of electrons
- B. Hybridization of orbitals
- C. Losing electrons
- D. Sharing electron
The atomic number of an atom would be equal to its mass number if it
- A. has a totally filled valence shell
- B. has a high charge to mass ratio
- C. does not contain neutrons
- D. exhibits isotopy
How many electrons does \({31}_{15}\)P\(^3-\) contain?
- A. 12
- B. 15
- C. 16
- D. 18
Consider the reaction represented by the following equation:
AgNO\(_3\) + NaCl โ AgCl + NaNO\(_3\).
The steps that could be taken to obtain pure dry sample of AgCI (s) from the mixture includes
- A. heating to saturation and drying
- B. filtering and evaporation to dryness
- C. filtering, washing and drying
- D. crystallizing and allowing to cool
The metallic bond in magnesium is stronger than that in calcium because magnesium has a
- A. larger atomic size.
- B. smaller atomic size
- C. greater number of valence electrons
- D. lower melting point
Which of the following arrangement of elements is in decreasing order of electronegativity?
- A. Na, Mg, Al, Si, P
- B. Na, A1, Mg, P, Si
- C. P, Mg, Na, Si, Al
- D. P, Si, Al, Mg, Na
Which of the following metals does not react with water to produce hydrogen?
- A. Copper
- B. Potassium
- C. Sodium
- D. Zinc
“Electrons always occupy the lowest empty energy level” is a statement of
- A. Aufbau Principle
- B. Hund's rule
- C. Pauli Exclusion Principle
- D. Periodic law
. If 20 cm\(^3\) of sodium hydroxide was neutralized by 20 cm\(^3\) of 0.01 mol dm3 tetraoxosulphate(VI) acid, what is the concentration of the solution?
- A. 0.010
- B. 0.020
- C. 0.100
- D. 0.150
How many moles of H\(_2\)SO4 are there in 50 cm\(^3\) of 0.108 mol dm\(^3\) solution of the acid?
- A. 5.4x 10
- B. 5.4 x 10\(^{-3}\)
- C. 5.4 x 10\(^{-2}\)
- D. 5.4x 10\(^{-1}\)
Which of the following statements about the solubility of a salt is correct?
- A. A salt whose solubility increases with temperature would not crystallize easily on cooling
- B. A salt whose solubility is independent of temperature would normally crystallize out on cooling
- C. Crystallization would be efficient in separating out a salt whose solubility increases considerably with temperature
- D. Solubility of a solid does not affect its crystallization