CHEMISTRY EXAM QUESTIONS| FIRST TERM EXAMINATION, 2018/2019 SESSION

CHEMISTRY EXAM QUESTIONS| FIRST TERM EXAMINATION, 2018/2019 SESSION

CHEMISTRY EXAM QUESTIONS| FIRST TERM EXAMINATION, 2018/2019 SESSION

CLASS: SS1       SUBJECT:  CHEMISTRY      TIME: 2 HOURS

SECTION A – OBJECTIVES [50MARKS]

Instructions: Answer all questions


  1. Chemistry can be applied in the following fields EXCEPT A. Agriculture Oil and gas  C. Politics  D. Metallurgy
  2. Separation of mixtures of solids with various sizes can be done
  3. Magnetic separation B. Coarsing C. Sublimation   D. Sieving
  4. Which of the following is an example of a chemical change?
  5. Dissolution of salt in water B. Rusting of iron C. Melting of ice
  6. Separating of mixture by distillation
  7. These are basic particles from which matter could be made EXCEPT
  8. Salt B. Atoms C. Ions   D. Molecules
  9. A molecule of neon is A. Diatomic Ionic  C. Triatomic  D. Minoatomic
  10. Which of these requires crystallization most? A. Drug making Cement making  C. Paint making  D. Perfume making
  11. Which one is the odd-one out? A. Air Urine  C. Brass  D. Sand
  12. Chemical hypothesis is different from chemical law that A. Hypothesis is not reasonable explanation to observation made while law is reasonable Hypothesis is a reasonable explanation to observations while law is a statement from a scientist   C. Hypothesis is a reasonable explanation to observations while law is a statement which confirms the hypothesis after extensive tests  D. None of the above
  13. Separating funnel is used for separating a mixture of A. Liquids with different boiling points  Liquids with sediment  C. Liquids with different colour  D. Liquids that are immiscible
  14. The simplest unit of water that retains its properties is called? An atom   B. An element  C. An hydroxide   D. A molecule
  15. Of the basic particles that make up an atom, the one with the smallest mass is A. A proton A neutron   C. An     D. An electron
  16. The atomic mass of an element is mostly due to the mass of A. Electrons and protons Electrons and neutrons  C. Protons and neutrons
  17. Positions and neutrons
  18. One of the following is NOT a branch of chemistry Analytical chemistry   B. Medicinal chemistry  C. Organic Chemistry  D. Hybrid chemistry
  19. One of these professions has no need for chemistry A. Mining
  20. Engineering C. Philosophy D. Geology
  21. How many molecules are there in 1 mole of chlorine molecules? A. 35.5 molecules 6.02 x 10-23 molecules  C. 17.0 molecules  D. 6.02 x 23 molecules
  22. A heterogeneous mixture can be defined as any mixture A. Whose compositions combine to produce a uniform substance Whose compositions combine to produce a non-uniform substance  C. Formed by solids and liquids  D. Of a solute and a solvent
  23. Atomicity of Ozone is A. 1 2    C. 3   D. 4
  24. The relative molecular mass of Lead (ii) trioxonitrate (v) is? (Pb = 207,

N = 14, O = 16) A. 170  B. 222   C. 232  D. 132

  1. The percentage of oxygen in sulphur(iv) oxide is (S = 32, O=16) A. 5%   50%   C. 500%   D. 25%
  2. The empirical formula of CH6 is CH  B. C3H3   C. C6H6   D. 3CH
  3. Which of the following techniques can be used to obtained ethanol from a mixture of ethanol and water? A. Boiling Chromatography
  4. Crystallization D. Distillation
  5. What is the relationship between empirical formula and molecular formula? A. Empirical formula = Molecular formula Empirical formula  = n x molecular formula (n=1,2,3…)   C. Molecular formula = n x Empirical  formula (n = 1, 2,3…) D. Molecular formula x Empirical  formula = 1
  6. Based on the IUPAC way of representing symbols, the symbol for Iron is A. He   Ir    C. Ion  D. Fe
  7. Calculate the percentage by mass of Lead in 1 mole of Pb (NO3)2

(Pb = 207; N = 14, 0 = 16) A. 76.9%   b. 62.5%   C. 77.5%   D. 87.3%

  1. How many moles of magnesium atoms are present in 0.80g of magnesium? (Mg = 24) A. 0.003mole 0.30mole  C. 0.33mole
  2. 0.03mole
  3. Modern standard element with which chemists define relative atomic mass  is A. 12C    13C    C. 3H   D. 14C
  4. Which of the following are mixtures? (i) Petroleum (ii) Rubber latx  (iii) Vulcanizers solution (iv) carbon (ii) sulphur  i, ii and iii   B. i, ii and iv   C. i  and iii only  D. i  and iv
  5. Which of the following substances is NOT a homogenous mixture?
  6. Filtered seawater B. Soft drink c. Flood water   D. writing ink
  7. Fractional crystallization is a method of separating A. Crude oil
  8. Liquid-liquid mixture C. coal D. solids of different solubilities in a liquid
  9. There are three main states of matter; liquid, solid, and gas. All have different properties. Which statement describes the physical state of a solid but not a liquid or gas? A. It has its own shape It does not have its own shape  C. It takes the shape of its container   D. It changes shape with temperature
  10. Which of the following is a property of both liquids and gases, but not solids? A. Can flow Can be compressed  C. Has a definite shape
  11. Has a definite texture
  12. Chemical symbol represents A. Chemical formula Molecular formula  C. Structural formula  D. Atomic formula
  13. A modern model of an atom show that electrons are present outside the nucleus in region of highest A. Probability Velocity  C. Speed
  14. Energy level
  15. Smaller particles in an atom are called A. Atomic particles Subatomic particles  C. Smaller particles  D. Neutral particles
  16. At room temperature, helium does Not have a definite shape or volume. Which state is it in? A. Gas  Solid  C. Water  D. Liquid
  17. Which property determines whether one substance will sink or float in another substance? A. Texture Density  C. Volume   D. Temperature
  18. The water supply system in your town is contamin with salt water. Drinking water can be obtained from the contaminated water by A. Filtration Evaporation  C. Crystallization  D. Distillation
  19. Which of the following methods would you recommend to recover Iron pieces from a garbage dump containing dry leaves, papers and broken glass? A. Burning of leaves and paper  Filtration  C. Hand picking of iron pieces  D. Magnetic separation
  20. The criteria to verify the purity of a solid substance are I. Boiling point Melting paint  III. Density  IV. Refractive Index  A. I, II   B. II, III  C. I, II, III  D. I, IV
  21. Valency is the combining power of an element. The valency of Nitrogen is A. 1 2     C.3   D. 2 or 3
  22. What is the mass in grammes of 0.50mole of oxygen atoms? (O= 16)
  23. 0.50g B. 2.0g   C. 5.0g   D. 8.0g
  24. The mass spectrometer is used to measure A. The number of protons in the nucleus of atom  The number of electrons in an atom  C. The relative molecular mass of an atom  D. Quantity of mass
  25. A molecule of neon is A. N N2  C. Ne  D. Nez
  26. One mole of oxygen atoms A. Has a molar mass of 32g Has 6.02 x 1023 molecules  C. Can be represented as O2   D. Contains Avogadro’s number of atoms
  27. The constituents of a leaf pigment can be separated by
  28. Chromatography B. Filtration C. Fractional crystallization
  29. Fractional distillation
  30. An element X with relative atomic mass 16.2 contains two isotopes with relative abundance of 90% and  with relative abundance of 10%. The value of m is A. 14   12   C. 18    D.16
  31. What is the percentage of mass of sodium in sodium hydroxide (Na = 23, O = 16, H =1) A. 40.4%   42.5%  C. 57.2%  D. 73.0%
  32. Neutral atoms of neon with atomic number 10 have the same number of electrons as A. 02- Ca2+   C. K+   D. S2-
  33. The modern way of representing symbols was developed in 1818 by
  34. Einstein B. Berzelius C. Dalton   D. Rutherford
  35. In countries where temperatures are most times far below zero, why is common salt sprinkled on the icy-roads? A. To remove impurities  To lower the melting point of the ice

SECTION B – THEORY

Instruction: This section is divided into two parts. Attempt only ONE question in part I and any THREE (3) questions in Part II


PART I [40MARKS]

  1. Using a neat diagram, explain how a mixture of two immiscible liquids of your choice can be separated.

2a.     Define the terms (i) mixture  (ii)compound. Give three differences between them

  1. Classify the following substances as an element, a mixture or a compound (i) Limestone (ii) Diamond  (iii) Sand (iv) Soil (v) Urine (vi) Bronze  (vii) Sugar (viii) Gold   (ix) Clay  (x) Urea  (xi) Antimony   (xii) Soap (xiii) Milk  (xiv) Air  (xv) Neon  (xvi) Iron
  2. Why is sodium chloride solution regarded as a mixture?
  3. How would you separate the components of the following mixtures?

(i) A mixture of sodium chloride and ammonium chloride  (ii) A mixture of Iron dust and zinc dust  (iii)A mixture of water and sugar

(iv) A mixture of two solids which have widely different solubilitus in water  (v) A pure solid from a concentrated solution of its salt.


PART II  [ 60 MARKS]

 State Dalton’s atomic theory and its corresponding modification

4a.     How is a Homogenous mixture different from a Heterogeneous mixture?

  1. Classify each of the following changes as either a physical change or a chemical change

(i)       The addition of water to quicklime

(ii)      The melting of candle ware

(iii)     The change in colour of zinc oxide from white to yellow when

Heated

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

(v)      The addition of a base to an acid to form salt and water only

5a.     Define the relative atomic mass of an element

  1. Calculate the relative molecular mass of;
  2. Slaked lime, Ca(OH)2
  3. Sodium trioxonitrate(v), NNO­3

iii.      Hydrated copper(ii) tetraoxosulphate(vi), CuSO4 – 5H2O

  1. What do you understand by the atomicity of an element?

(Ca = 40; O = 16;  H=1; Na = 23; N = 28; S = 32; Cu = 64)

  1. Find the empirical formula of a compound which on analysis yields the following as the reacting masses. Carbon = 2.0g, hydrogen = 0.34g, Oxygen = 2.67g. from your result, find the molecular formula of the compound, if its relative molecular mass is 60.

7a.     Define the following

(i) Mole   (ii) Molecule   (iii) Iron   (iv) atom

  1. How many moles are there in 20g of CaCO3?
  2. Calculate the percentage by mass of nitrogen in trioxonitrate(v) acid