CHEMISTRY FIRST TERM EXAMINATION SS 2

   FIRST TERM

Examination malpractices may lead to a repeat of the subject or suspensions don’t be involved.

SUBJECT: CHEMISTRY                     TIME: 2HRS             CLASS: SS  2

1.Which property decides the order of the elements in the Periodic Table?
a. masses of their atoms     b. number of electrons in the outer shell
c. number of neutrons in the nucleus   d. number of protons in the nucleus
2. The element with a proton number 12 has similar chemical properties to the element with the proton number             a. 2          b. 11   c. 13         d. 20
3.  An element with atomic number 20 is placed in which period of the periodic

table?           (a) 4                 (b) 3    (c) 2                  (d) 1

4. Which statement about a new element, which has seven outer electrons in its atoms, is correct?
   a. it is monatomic b. it forms a covalent compound with hydrogen
   c. it forms a positive ion d. it forms covalent compounds with Group I elements
   5. Which list contains 3 elements that all exist as diatomic molecules at room temperature?
   a. hydrogen, fluorine, neon      b. nitrogen, chlorine, neon           c nitrogen, oxygen, fluorine
   d. oxygen, chlorine, helium
   6. Which statement shows that iron is a transition metal?     a. Iron(II) sulphate crystals are green
   b. Iron(III) oxide is basic      c. Iron rusts in moist air
   d. Iron reacts with dilute hydrochloric acid
   7. A metal X forms oxides with the formulae XO and X₂O₃ ,Where is X in the Periodic Table?
   a. Group II   b. Group III     c. second Period      d. transition elements
   8. Which of the following is a property of aqueous potassium iodide?
   a. it does not conduct electricity       b. it is decolorised by chlorine
   c. it reacts with aqueous bromine to form iodine    d. it reacts with aqueous lead(II) nitrate to form a white precipitate
5. Hydrogen can be placed along with group 7 elements because it

(i) can aquire noble gas configuration by gaining one electron.

(ii) exhibits oxidation state of+ 1.

(iii) has one electron in the outermost shell.

(iv) can exhibit oxidation state of -1.

(a) (ii) and (iii) (b) (i) and (iv)          (c) (i) (d) (iii).

10. . A solid substances with high melting and boiling points is likely to be a/an
11. covalent compound B. dative covalent compound C. electrovalent compound
12. non-metal

11.Alkali metals           a. forms covalent bonding with the halogens

b.have their melting point decrease down the group     c.forms hydroxides when reacted with water

d.have their reactivities decrease down the group

12. The periodic table is an arrangement of elements in order of their
13. mass numbers b .relative molecular masses c. atomic numbers        d. isotopic masses
14. molecular masses.
15. Which statement about groups in the Periodic Table is correct?
16. All groups contain both metals and non-metals. b. Atoms of elements in the same group have the same total number of electrons. c. In Group I, reactivity decreases with increasing proton number.
17. In Group VII, the melting point of the elements increases with proton number.
    14. . Which of the following sets of elements have the same similar electronic

configuration?              (i) H, He, Be               (ii) Li, Be, B   (iii) He, Ne, Ar            (iv) Li, Na, K

(a) (iii)                         (b) (iii), (iv)               (c) (iv)                         (d) (ii), (iii)

15.Calcium and magnesium belong to the same group in the periodic table because

Both    A. are metals     B. form colourless salts  C. have the same number of valence electrons

1. form cation
2. Which of the following elements is a d-block element? A. calcium b. iron C. lithium D. silicon
3. Which statement is most likely to be true about the elements in Group I of the Periodic Table?
4. They occur uncombined in nature. b. They are equally reactive chemically.
5. They form chlorides of similr fornulae.
6. They become less metallic as the proton number increases.
7. Astatine (At) is in Group VII of the Periodic Table. Which of the following is a property of astatine? a. It forms a basic oxide. b. It is a good conductor of electricity.
8. It is displaced by chlorine from aqueous potassium astatide.
9. It displaces iodine from aqueous potassium iodide.
10. Which statement about a new element, which has seven outermost electrons in its atoms, is correct?
11. It is monatomic. b. It forms a covalent compound with hydrogen.
12. It forms a positive ion. d. It forms covalent compounds with Group I elements.
13. Fluorine is the first element in Group VII of the Periodic Table. Which statement will not be true of fluorine? a. Fluorine exists in diatomic molecules. b. Fluorine forms negative ions.
14. Fluorine is less reactive than chlorine. d. Silver fluoride will be sensitive to light.
15. If X is a group III element. Its oxide would be represented as A. X₃O₂ B. X₃O C. X₂O₃ D. XO₃
16. Transition metals are:

(a) found between groups 2 and 3  (b) all solids (c) metals and semi-metals (d) found between groups 1 and 3.

23. The mode of conduction of electricity by metals differs from that of aqueous

solutions because

a.metals are reducing agents and aqueous solutions are not

b.metals are good conductors and aqueous solutions are not

c.metals ionize readily and aqueous solutions do not

1. mobile electrons carry electricity in metals and mobile ions in aqueous solutions
2. Keeping in view, the periodic law and periodic table, suggest which of the

following elements should have maximum electronegative character?

(a) Oxygen      (b) Nitrogen  (c) Fluorine      (d) Astatine.

25.Based on the the position of the elements in the electrochemical series,hydrogen

(H+) will be discharged before         a.Au ⁺      b.Hg ⁺           c.Hg ⁺    d.Al ³⁺      e.Cu ²⁺

26.The chemical reactions which takes place at the anode in electrolysis is a .

Oxidation b.hydrolysis c.dissociation d.reduction e.ionization

27.Oxidation is a process involving a.gain of electrons b.loss of electrons

c.gain of hydrogen d.loss of oxygen e.ion exchange.

28.Consider the reaction,   Zn_(s) +CuSO_{4 (aq)}  à  ZnSO_{4 (aq)} +Cu_(s)

Which of the following statements is true about the reaction? A.it is not a redox

reaction b.Zinc has been reduced c.Copper is obtained in the product by

reduction d.CuSO₄ is the reducing agent e.Cu²⁺ acted as an oxidizing agent.

29.The electrolytes used in car battery is

a.ammonium chloride     b.dilute tetraoxosulphate (vi)acid    c.dilute trioxonitrate(v) acid   d.ethanoic acid

30.Consider the reaction represented by the following equation:2H₂S +SO₂ à2H₂O +3S

SO₂ is acting as the      a. dehydrating agent     b. reducing agent   c. precipitating agent

1. oxidizing agent
2. Consider the reaction represented by the following equation:

5Fe ²⁺ +MnO₄ ^– +8H ⁺  à5Fe ³⁺ +Mn ²⁺ +4H₂O   (a) Fe²⁺    (b) MnO₄^–   (c) H⁺   (d)H₂O

Which of the species is reduced?a.Fe 2+ b. MnO 4 – c.H + d.H₂O

32.Bismuth is in group 5A of the periodic table.Its chemistry will resemble that of

a.Aluminium b.Oxygen c.Phosphorus d.Iodine

33.In which of the following is the oxidation number of chlorine zero?

1. CCl ₄ b.Cl₂O C. Cl₂   d. NaCl

34.What is the change in the oxidation number of Mn in the following equation?

MnO 4 – (aq) + 8H + (aq) +5e – ——-Mn 2+ (aq) +2H 2 O (l)

a.+8 to+2 b.+7 to+2 c.- 4 to+2 d.- 1 to+2

35.CuSO₄ solution is electrolysed using carbon electrodes ,which of the following

are produced at the anode and cathode respectively?

a.copper and oxygen  b. oxygen and copper c. Hydrogen and copper d. Copper and Hydrogen

36.Calculate the quantity of electricity required to deposit 64.0g of copper from

molten CuCl₂ ?{Cu=64,F=96500c}    a.6.18×106 c b.3.09x106c c.1.93x105c    d.9.65x104c

37.The ions in a solution that conduct electricity are a.electrodes b.electrolytes

c.non-electrolytes d.electrode potentials

38.What is the quantity of electricity produced when a current of 0.5A is passed for

5hours 45minutes?(F=96500c).    a.0.11F b.0.22F c.0.12F d.1.1F

39 . Which one of the following is usually described as a reducing agent?
a. carbon monoxide    b. concentrated sulphuric acid   c. copper(II) oxide d. Sodium oxide

40.An oxidisng agent was observed to turn from orange to green. It is most likely to be:
a. acidified potassium manganate (VII)   b. acidified potassium dichromate (VI)
c. maganese (IV) oxide    d. iron (III) chloride

41. When iron (III) sulphate is reduced to iron (II) sulphate, the colour of the solution turns from
    a. brown to yellow b. green to yellow  c. red to colourless   d. brown to green
42. Cu+ ions may be formed when
    a. Cu2+ ions are oxidised by sulphur dioxide b. Cu2+ ions are reduced by copper
    c. Cu is oxidised by nitric acid   d. Zinc is placed in copper sulphate solution
43. H₂S(g) + Cl₂(g) → 2HCL(g) + S(s) The reaction is interpreted as
44. H₂S is getting oxidized and Cl₂ is getting reduced
45. H₂S is getting reduced and Cl₂ is getting oxidized C. Only H₂S is oxidized D. Both H₂S and Cl₂ are reduced”
    Among the elements B, Al, C and Si

44 . Which has the highest first ionization energy?

45. Which has the most negative electron gain energy?
46. Which has the largest atomic radius?
47. Which has the most metallic character?

48.The most electropositive element in second period is ……

49. whereas the most electronegative element is …….
50. The ionization energy of nitrogen is …… than that of oxygen.

 

 

 

 

SECTION B

ATTEMPT QUESTION 1 AND ANY OTHER TWO QUESTIONS.

1a. Explain briefly, in terms of electronic configurations, the occurrences of periods, groups and transition series in the periodic table.

1. Define atomic radius, first ionization energy and electronegativity.
2. Discuss their trends across the periods and down the groups in the Periodic Table.

 

2a.What is the oxidation state of chromium atom in Cr(H₂O)₆³⁺

2b.Balance this equation in acidic medium

MnO₄^–(aq) + SO₃^2-(aq) –> MnO₂(s) + SO₄^2-

c.Balance in alkaline form.

Ag(s)+Zn²⁺(aq)→Ag₂O(aq)+Zn(s)

1. Name two compounds commonly used as oxidizing agents in the Laboratory.

 

3a. Write half cell equation of reaction for the following equation.

Cu(s) + 2Ag ⁺(aq)—— Cu ²⁺(aq) + Ag(s)

3b. State the 2nd law of electrolysis.

3c. 36g of copper was deposited during the electrolysis of copper (ii)

tetraoxosulphate (iv) solution using copper electrodes. Calculate the quantity

of electricity required for the reaction. (Cu=63.5, 1F= 96,500).

3d. Explain what happens when an electric current is passed through

Aqueous calcium chloride using graphite electrode .

 

4a. Explain what happens when an electric current is passed through  aqueous sodium chloride

1. 0.222g of a divalent metal is deposited when a current of 0.45A is passesd

through a solution of its electrolyte for 25minutes using platinum electrodes.

Calculate the relative atomic mass of the metal.{1F=96500c}

8. Calculate the current in amperes that will deposit 8.00g of calcium from fused

CaCl₂ in 1hour 15minutes.{Ca=40.0;1Faraday=96500C}

 

5a.What is the voltage of the cell represented as Zn(s)/Zn ²⁺ (aq)//Cu ²⁺ (aq)/Cu(s)?

Given that Cu ²⁺ (aq)/Cu(s) E⁰=+0.337V

Zn(s)/Zn ²⁺ (aq) E⁰=0.763V

b.A current of 3.2 amperes was passed through fused aluminium oxide for 10

minutes, calculate the mass of aluminium deposited.

Al = 27

1. Calculate the time it will take to deposit 1 mole of silver,if a current of 6A is

passed through a solution of silver trioxonitrate (v).

1. Describe the differences between an Electrolytic cell and an Electrochemical

cell.

 

 

 

 

 

 

 

 

 

 

 

                         

Examination malpractices may lead to a repeat of the subject or suspensions don’t be involved.

SUBJECT: CHEMISTRY                     TIME: 2HRS             CLASS: SS  1

1. Scientific approach to discoveries follows the order which includes

(a) further experiment and problem solving          (b) theory, negative and positive results and experiments              (c) experiments, hypothesis and results.             (d) observation, hypothesis and experiments

2. Chemical hypothesis is different from chemical law in that.

(a) hypothesis is not reasonable while law is reasonable

(b) hypothesis is a reasonable explanation to observations made while law    is a statement from a scientist.

(c) hypothesis is a reasonable explanation to observation while law is a statement which confirms the hypothesis after extensive tests.

(d) none of the above.

3. Which of the following is correct about water molecule?

(a) it is made  up of  2 oxygen atoms and 1 hydrogen atom

(b) it consists of 1 hydrogen atoms and 1 oxygen atoms.

(c) it is made up of 2 hydrogen atoms and 2 oxygen atoms

(d) it consists of 2 hydrogen atoms and 1 oxygen atoms

4. Which of the following is the smallest particle that have the properties of an element?

(a) ion  (b) molecule (c) an atom (d) element

5. Which of the following compounds have atomicity greater than 2?

(i) H₂0 (ii) NaCl (iii) H₂S (iv) Co₂

(a) i, ii and iii  (b) ii, iii and iv  (c) I and ii only  (d) i, iii and iv

6. When an atom gains an electron, its becomes

chemically inactive (b) Negatively charged (c) oxidized (d) a cation (e) a complex ion

7. The valence of sodium (Na) is         (a) 2 (b) 1 (c) 3 (d) 8
8. Given the symbol ⁴⁰ Y, it can be deduced that Y has.

  ₂₀

60 neutrons (b) an atomic number of 20 (c) a mass number of 60  (d)  40 electrons  (e) 40 protons

9. The mass number of an atom is the sum of its

(a) Electrons, neurons and protons             (b) Electrons and protons

(c) protons and neutrons        (d) Orbital electrons        (e) Valence electrons

10. A molecule of neon is     (a)  ionic (b) diatomic (c) monoatomic (d) polyatomic
11. Chemical changes around us include all except

(a) rusting of iron nails (b) fading of coloured cloths (c) sieving (d)

decomposing of green leaves in a compost

12. One of these is not a chemical change

(a) rusting (b) sublimation of solids (c) slaking of quicklime (d) fermentation

of glucose.

13. One of these professions has no need for chemistry.

(a) miners (b) engineers (c) philosophers (d) geologists

14. The following are examples of radical except (a) OH^– (b) NH ₄ ⁺ (c) N0 ₃ ^– (d) Cl ^–
15. Which of the following atoms contains the highest number of electrons in the

outermost shell?   (a_{) 8} O (b) ₁₀ Ne (c) ₁₅ P (d) ₁₉ K

16. What is the mass number of an element of its atom contains 10 protons, 10

electrons and 12 neutrons    (a) 32 (b) 22 (c) 20 (c) 10

17. In which pair of substances is each substance a mixture?
    a. air; water b. limewater; water c. quicklime; limewater  d. sea water; air
    18. A separating funnel is most useful to separate  a. a residue from a solution  b. two immiscible liquids  c. a solute from a solvent   d. two powdered solids
18. Separation of different compounds in paper chromatography depends on the
19. difference in colour b. size of container used c. type of filter paper used
20. relative solubilities of the compounds
21. Which separation technique is used to obtain potassium trioxonitrate(v) from its aqueous solution?
22. electrolysis b. distillation c. chromatography  d. crystallisation
23. What property must a mixture of miscible liquids have in order for it to be separated by fractional distillation?
24. the liquids in the mixture must be coloured
25. the liquids in the mixture must have the same densities
26. the liquids in the mixture must have close boiling points
27. the liquids in the mixture must have different boiling points
28. Which is the best method to separate a mixture of lead tetraoxosulphate(vi) and sodium trioxonitrate(v)? a. filtration b. distillation c chromatography  d. crystaliisation
29. What is the best method to separate liquid air into its constituents?
30. crystallization b. distillation c. fractional distillation   d. chromatography
31. Which ion has the most shells that contain electrons?
    a. Al³⁺ b. Be²⁺ c. N^3-   d. S^2-
    25. Which electron arrangement is that of a metallic element?
    a. 2, 1    b. 2, 4    c. 2, 5        d. 2, 7
    26. An atom of an element contains 17 protons, 18 neutrons and 17 electrons. What is the atomic structure of another isotope of this element?

	protons	neutrons	electrons
a	17	20	17
b	17	18	16
c	18	18	17
d	20	18	17

27. Which of the following is a compound?
    a. air b. carbon c. oxygen   d. steam
    28. In which set do the three particles each have the same total number of electrons?

a	Cl–	Br–	I–
b	F–	Ne	Na+
c	K+	Ca2+	Br–
d	Li+	Na+	K+

 

 

 

 

29. An ion X⁺ has 23 nucleons and 10 electrons. What does the nucleus of the ion X⁺ contain?

	protons	neutrons
a	12	11
b	11	12
c	10	13
d	9	14

30. The table shows information about particles X and Y.

	number of protons	number of neutrons	electronic structure
X	9	10	2, 8
Y	17	20	2, 8, 8

Which statement is correct for both X and Y?
a. they are atoms of metals  b. they are atoms of noble gases  c. they are isotopes of the same element
d. they are negative ions
31. Isotopes of a given element have the same

(i) atomic number (ii) electronic configuration (iii) chemical properties (iv)mass number

(a) iv only (b) i and iii only (c) iii and iv (d) i, ii and iii

32. The maximum number of quantum number of electrons that can be

accommodated in the shell having the principal quantum number 3 is?

(a) 3 (b) 9 (c) 10 (d) 18 (e) 32

33. In which of the following is the oxidation number of nitrogen zero?

(a) NH 3 (b) NaNO₃ (c) HNO ₂ (d) N ₂ (e) NCl₃

34. The oxidation number of phosphorus in PO ₄^-3 is (a) +1 (b) +2 (c) +3 (d) +4 (e) +5
35. The most suitable method to use when separating an insoluble solid from s

liquid is     (a) Evaporation (b) filtration (c) magnetization (d) sublimation (e) distillation

36. A sample of orange juice is suspected to have been contaminated with a

yellow dye. Which of the following methods can be used to detect the dye?

(a) decantation  (b) chromatography  (c) distillation  (d) filtration (e)Evaporation

37. If an element X with the electronic configuration of 2,8,3 combines with

another element Z with electronic configuration 2,8,6, the compound formed

will have the formula   (a) XZ (b) XZ ₂ (c) X ₂ Z (d) X ₂ Z ₃ (e) X ₃ Z ₂

38. The __________ is the pure liquid that is obtained after its vapour condenses in the
    condenser.
39. Distillation is essentially the process of _______Z___ a liquid and 40. __________ the vapour.
    ATTEMPT ANY THREE

1a. Use a suitable diagram to show how one state of matter can be converted to another state.

1. Classify the following as either physical or chemical change.

The addition of water to quick lime

The change of wax

The change in colour of Zinc from white to yellow and vice versa when heated and after cooling respectively.

The dissolution of copper in concentrated trioxonitrate(v) acid.

The hardening of cement by the absorption of carbon(iv)oxide.

1. Write the first 10 elements their symbols and their electronic configurations.

2a.      Give two examples each of the following:

A monatomic element:

A diatomic element:

1. Give two examples each of:

An element that exists as a solid at room temperature.

An element that exists as a liquid at room temperature.

(iii)An element that exists as a gas at room temperature

1. What is the Latin name and the symbol of the following elements.
2. Gold ii. Lead iii. copper   d. Iron

3a. Classify the following substance as either mixture or compound

Soap            Table salt         Sugar            Toothpaste      Crude oil

Perfume        Limestone       Tea Solution    Air                Milk

Paint             Drugs (aspirin)  Urea          Blood           Bronze

Soil                Sand                 Saliva          Urine           Water

3b. Which separation method would you employ to separate each of the following

mixtures?

Kerosene and water

blood components

sand and iron filings

(iv )    components of crude oil       (v )     Ammonium chloride and chalk

(vi)      table salt and water         (vii)    palm oil and water

(viii)   components of sea water

(ix)     common salt and sand

(x)       copper(ii)tetraoxosulphate(vi)crystal and water.

3c. List the postulate of Dalton’s atomic theory.

4a. Calculate the % abundance by mass of the elements with this relative abundances.

30. ³¹ ₁₉ P and ³⁰ ₁₉ P and relative atomic mass 30.5
31. Determine the relative atomic mass of carbon from a sample with the

following data   98.9% of carbon -12 and 1.1% of carbon-13.

4a. Calculate the oxidation state of the elements  indicated in the following, bearing in mind the rules for determining oxidation states.

i.K₂Cr₂O ₇             Cr

4. CuSO₄.5H₂O S

iii. Na₂CO₃ .10H₂O       C

iv.H ₂ SO ₄                        S

v.H ₂ SO₃                  S

4b. State the 3 principles for filling electrons into orbitals

4c. State the factor that determines which liquid distills over first during fractional distillation.
5a. Describe how you can separate ammonium chloride from a mixture of ammonium chloride and sodium chloride.

5b. State the difference between simple and fractional distillation

5c. The solid which remains on the filter paper when a suspension is filtered is called the
__________.
5d. The liquid or solution that passes through the filter paper is called the __________.
5e. Some salts are obtained through crystallisation from a saturated solution while others
are heated and evaporated to dryness. Describe one factor that determines the choice of
method