Chemistry SS 1 Second Term Exam

SECOND TERM

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

SUBJECT: CHEMISTRY

DURATION: 2 ½ HRS

CLASS: SSS 1

1. Which of the following decreases when a given mass of gas is compressed to half its initial volume?(a) average intermolecular distances b. frequency of collisions c. number of molecules present d. atomic radius of each particle
2. Calculate the mass of chlorine gas which occupies a volume of 1.12dm³ at s.t.p (Cl=35.5,1 mole of gas occupies 22.4dm³ at s.t.p a.1.80g b.3.55g c.7.10g d.15.50g
3. Determine the mass of sulphur (iv) oxide obtained when 91.0g of oxygen reacts completely with sulphur according to the following equations S_(s)+O₂——-SO₂(g).(S=32,O=16) a.123g b.139g c.155g d.182g
4. Which of the following elements form an ionic chloride? A. magnesium b .carbon c. phosphorus d. Hydrogen
5. The bond between two iodine molecules is (a).co-ordinate bond (b) electrovalent bond (c).ionic bond (d) van derwaal’s forces
6. Bonds between a highly electronegative atom and a hydrogen from another molecule is called (a).hydrogen bond (b).covalent bond (c).intermolecular forces (d).ligand.
7. The nitride ion is N^-3.What is the formula of the nitride of an alkali metal X. a.X₃N₅ B.XN₃ C.X₂N₃ d.X₃N
8. What type of chemical bonding is involved in the formation of NH₄⁺ from a molecule of ammonia and a proton. a. Hydrogen bonding b. co-ordinate covalent bonding c. electrovalent bonding d. covalent bonding
9.  Which component of the air is removed when air is bubbled through a solution of alkaline pyrogallol? Carbon (iv) oxide b. helium c. nitrogen d. oxygen e. water vapour
10. Which law is obeyed when 1 volume of Hydrogen reacts with 1 volume of chlorine to form 2 volumes of Hydrogen chloride? a.Law of constant composition b. Boyle’s law c. Charle’s law d. Gay Lussac’s law e. law of reciprocal proportions
11. What volume of oxygen in dm3 is given off at s.t.p. When 17g of Hydrogen peroxide completely decomposes according to the following equation 2H₂O_2(l)——-2H₂O_(l)+O₂(g) (H=1 ,O=16 and the molar volume of a gas at s.t.p=22.4dm³) a.32 b.22.4 c.11.2 d.5.6 e.2.8
12.  One mole of a substance contains the atomic mass b. Avogadros number of particles c. mass number d.oxidation number e. quantum number
13. The gas law represented by the mathematical expression,p=p1+p2+p3 is avogadro’s law b. Daltons law of partial pressure c. Grahams law of diffusion d. law of constant composition e. law of multiple proportion
14.  What is the volume occupied by 2 moles of ammonia at S.T.P? a. 44.8dm^-3 b. 22.4dm^–  c. 11.2dm^-3 d. 5.6dm^-3
15. The volume occupied by 0.4g of hydrogen gas at STP is (H=1.00, molar volume at STP =22.4 dm³(a) 2.24 dm³ (b) 4.48dm³ (c) 22.4dm³ (d) 8.96 dm³
16. What type of bond holds Hydrogen fluoride molecules together to form larger aggregates? a. covalent b. dative c. hydrogen d. ionic e. metallic
17. What is the percentage by mass of sodium in a molecule of Na₂CO₃.10H₂O? (H=1 , C=12, O=16 , Na=23) A. 160 b. 187 C. 186 D. 250
18. The relative molecular mass of a gas which has a vapour density of 16 is a.ʅ32/2 b. ʅ16 c.8 d.32 e.64
19.  What is the amount in mole of sodium trioxocarbonate (iv) in 5.3g of the compound?(CaCO3=106) a. 0.05 b.0.10 c.0.20 d.0.50 e.2.00
20.  Calculate the mas of chlorine gas which occupies a volume of 1.12dm3 at s.t.p.(Cl=35.5, 1 mole of gas occupie 22.4dm3 at s.t.p) a. 21.4 g b. 3.55g c. 31.7g d. 4.35g
21. Given that 32.0g of sulphur contains 6.02×1023 sulphur atoms, how many atoms are there in 2.7g of aluminium?(Al=27, s=32) a. 6.02 x10²³ b.3.01×10²³ c.6.02x 10²² d.5.08×10²² e.3.01×10²²
22.  Which of the following gives the products of the equation given below Zn(s) +HCl (aq)——– a.ZnCl₂+H₂ b. ZnCl₂+H c. ZnCl+H₂ d. ZnCl+H
23.  The molar mass of HNO₃ is (H=1, O=16, N=14) 53 b.73 c.63 d.5
24. What is the percentage by mass of copper in copper(i)oxide Cu₂O (O=16,Cu=64) a.88.9% b.80.0% c.66.7 d.20.5 e.11.1%
25. If the volume of a given mass of a gas at 00C is 27.3cm,what will be the volume of the gas at 100C, pressure remaining constant? a. 2.73cm³ b.28cm³ c.37.3 cm³ d.273 cm³ e.28.3 cm³
26. Which of these gases will have the highest rate of diffusion under the same condition?(H=1,C=12,O=16,S=32,Cl=35.5) a. O₂ B.Cl₂ c. HCl d.H₂S e.CO₂
27. A given volume of methane diffuses in 20seconds.How long will it take the same volume of sulphur(iv) oxide to diffuse under the same condition. (CH₄=16,SO₂=64) a.5 seconds b.20 seconds c.40 seconds d.60 seconds e.80seconds
28. The ratio of reactants to products is 1:3:2 in the reactions represented by the equation:N₂(g)+3H₂——–2NH_3(g) Which of the following laws is demonstrated by this? a.Boyle’s law b. Law of multiple proportion c. Gay Lussacs law d. Law of constant composition E. Avogadro’s law
29.  A solid substances with high melting and boiling points is likely to be a/an a. covalent compound b. dative covalent compound c. electrovalent compound d. non-metal
30.  If X is a group III element. Its oxide would be represented as a. X₃O₂ b. X₃O c. X₂O₃ d. XO₃
31.  What is the volume occupied by 2 moles of ammonia at S.t.p? a. 44.8dm^-3 b. 22.4dm^-3 c. 11.2dm^-3 d. 5.6dm^-3
32.  An organic compound contains 40.0% carbon, 6.7% hydrogen and 53.3% oxygen. What is the empirical formula of the compound?[O = 16.0, C = 12.0, H = 1.0] a.C₂HO b. CHO c. CH₂O d. CHO₂
33.  Which of the following statements about electrovalent compounds is not correct? a. crystals are formed b. electrons are shared c. ions are formed d. strong electrostatic forces are involved
34. Which of the following pairs of elements form a compound by transfer of electrons? a. carbon and chlorine b. carbon and oxygen c. hydrogen and chlorine d. potassium and chlorine
35. What is the value of X in the following equation? 2H₂S + SO₂→ 2H₂O + XS A. 6 B. 4 C.3 D. 2
36.  The law which describes the relationship between volume of a fixed mass of gas and its absolute temperature at constant pressure is a. Boyle’s law b. Charles’s law c. Gay Lussac’s law d. Graham’s laws
37.  The two types of bonds that exist in H₃O+ are A. covalent and ionic B. dative covalent and covalent C. metallic and ionic D. polar covalent and metallic
38.  Given that r is rate and p is density, the expression r α¹/_√P represent a. Boyle’s law b. Charles’s law c. Dalton’s law d. Graham’s law
39. .If the atomic number of an element X is 11 and that of oxygen is 8, the most likely formula of the oxide of X is? (a) X₂O (b) X₃O₂ (c) XO₂ (d) XO₃
40. An element X₁with electronic configuration 2,8,2 and element Y with electronic configuration 2,8,7 are likely to combine by (a) metallic bonding (b) covalent bonding (c) electrovalent bonding (d) dative bonding
41. The relative molecular mass of limestone CaCO₃ is [Ca =40, C=12, O=16]? (a) 65 (b) 105 (c) 100 (d) 312
42. All pure samples of a particular chemical compound contain similar elements combined in the same proportion by mass is the law of ? (a) conservation of mass (b) definite proportions (c) multiple proportions (d) reciprocal proportions
43. Which of the following compound is covalent? (a) CaCl₂ (b) MgO (c) NaH (d) CH₄
44.  All these are cause of luminousity in flames except; a. Solid particles b. Solid particles and increase temperature c. Solid particles and increased pressures. d. Size of materials burnt.
45.  The gases burn with blue flame except: a H₂ b. CH₄ c.2H₂ d.CO
46. Which of these is not necessary for metallic corrosion? a. Water b. Oxygen c. Heat d. Sulphur (iv) oxide
47.  The most abundant nobles gas in nature is: a. Neon b. Radon c. Helium d. Argon.
48.  Which type of bond exist between two atoms of an element with atomic number of 7.
49.  Which of the following exist as a molecular solid? a. Silica b. sodium c. iodine d. diamond
50.  If the atomic number of an element is 10, then the outermost shell will have
51. a. 2 electrons b.4electrons c.6electrons d.8electrons

THEORY

1(i)What volume is occupied by 24.5g of dichlorofluoromethane CF₂Cl₂ at s.t.p?

C=12 ,F=19 ,Cl=35.5 and 1 mole of gas at s.t.p occupies 22.4dm³ 4marks

(ii) Distinguish between dative and covalent bond 4marks

(iii) State the type of intermolecular forces present in:

a. hydrogen fluoride

b. argon 2marks

2(i) State Dalton’s law of Partial Pressure 2marks

(ii) If 200cm³ of carbon (iv) oxide were collected over water at 18^oC and 700 mmHg, determine the volume of the dry gas at s.t.p

(standard Vapour pressure of water at 18^oC = 15mmHg] 4marks

(iii) A hydrocarbon with a vapour density of 29 contains 82.76% carbon and 17.24% hydrogen.

Determine the:

I. empirical formula

II. molecular formula of the hydrocarbon

[H = 1.00 C = 12.00] 4marks

3.(i) Two different sample, 1 and 2 of Zinc oxide were obtained from different sources. When heated in a stream of hydrogen they were reduced to yield the results below.

Show that the result above explains the law of constant composition. 4marks

ii. What happens when a beaker of air is inverted over trough of water containing dissolved alkaline pyrogallol left overnight? 3marks

iii. What are the products of the combustion of a candle? Describe an experiment to identify the products of the burning candle. 3marks

4a.State the law of multiple proportion. 2marks

b. ii. A metal M forms two chlorides P and Q. On analysis,2.00 g of p was found to contain 0.69g of M and 10.0g of Q was found to contain 4.41g of M.

I Calculate the mass of chlorine which combined with 1.00g M to form P and Q respectively.

II. Deduce whether the law of multiple proportions is obeyed.

III. Write the correct formula of P and Q. 5 marks

c. If 250cm³ of a gas at s.t.p is heated to 27⁰C at constant pressure, calculate its new volume. 3marks

5.(a) State the type of chemical bonding which accounts for each of the following observations

Chlorine exists as discrete molecules

ii. Sodium chloride dissolves readily in water.

iii. CuSO_4(aq) forms a deep blue complex ion with excess NH_3(aq)

Name the type of bonds that exist in each of the following compounds:

iv.CaCl₂

v.NH₄Cl

vi.CCl₄ 3marks

(b).How many moles of calcium trioxocarbonate (iv) are there in 5.0g of calcium trioxocarbonate(iv)?(Ca=40, C=12,O=16) 1mark

c. Complete and balance this equation.

i. Mg_(s)+O₂——

ii. NaOH _(aq)+H₂SO₄

iii.H₂SO₄+Al(OH)₃—–

iv.KOH+H₂SO₄——– 6marks