First Term Examination
Class : SSS 1
Subject : Chemistry
Instruction: Answer all questions correctly in this section.
1. Chemistry is defined
2. All are basic particles from which matter could be made except ________ (a) salt (b) atom (c) ion (d) molecules
3. Atomicity of Ozone is _______. (a) 1 (b) 2 (c) 3 (d) 4
4. Modern standard element with which chemist’s define relative atomic mass is ______ (a) 12C (b) 13C (c) 3H (d) 14C
5. The relative molecular mass of Lead (II) trioxonitrate V is ______. (Pb =108, N = 14, O = 16). (a) 170 (b) 222 (c) 232 (d) 132
6. The percentage of oxygen in Sulphur IV oxide is ________. [S=32, O = 16] (a) 5% (b) 50% (c) 500% (d) 25%
7. A molecule of neon is ______. (a) diatomic (b) ionic (c) triatomic (d) monatomic
8. Which of the following substances is not a homogenous mixture? (a) Filtered seawater (b) Soft drink (c) Flood water (d) Writing ink
9. 3NH3 is ___________. (a) three moles of ammonium (b) three moles of ammonia (c) six moles of ammonia (d) six moles of ammonium
10. Atom is _________. (a) the smallest part of a substance that can take part in a chemical change (b) the smallest part of a compound that can take part in a chemical change (c) the smallest part of an element which can take part in a chemical change (d) the smallest part of a lattice which can take part in a chemical change
11. The empirical formula of C6H6 is _________. (a) CH (b) C3H3 (c) C6H6 (d) 3CH
12. Which of the following elements is diatomic? (a) Sodium (b) Oxygen (c) Iron (d) Neon
13. The separation of petroleum fractions depends on the differences in their ___________. (a) boiling point (b) molar mass (c) melting points (d) solubilities
14. Separation of mixtures of solids with various sizes include (a) Magnetic separation (b) Coarsing (c) Sublimation (d) Sieving
15. Which of the following phenomena leads to decrease in volume
16. Which of the an example of a chemical change? (a) Dissolution of salt in water (b) Rusting of iron (c) Melting of ice (d) Separating a mixture by distillation
17. A heterogenous mixture can be defined as any mixture _________. (a) whose composition is uniform (b) whose composition is not uniform (c) formed by solids and Liquids (d) of a solute and a solvent
18. A mixture of oil and water can be easily separated by ________. (a) sublimation (b) evaporation to dryness (c) using a separate funnel (d) fractional crystallization
19. One mole of oxygen atom ________. (a) has a molar mass of 32g (b) has 6.02 x 10 ^23 molecules (c) can be represented as O2 (d) has a formula mass of 16
20. If the relative molecular mass of CH2O is 60. Calculate its empirical formula. [C = 12, H = 1, O = 16] (a) 4 (b) 1 (c) 2 (d) 3
21. Which element has an electronic configuration of 1s2 2s2 2p6 3s1? (a) Calcium (b) Chlorine (c) Potassium (d) Sodium
22. Determine the maximum number of electrons that can occupy the principal energy level N of an atom. (a) 18 (b) 8 (c) 24 (d) 32
23. The electronic configuration 1s2 2s2 2p3 is (a) chlorine (b) Nitrogen (c) oxygen (d) neon
24. Which of these is the same in isotopes of an element? (a) Mass number (b) Number of neutrons (c) Relative atomic mass (d) Atomic number
25. Arrangement of ions in a regular pattern in a solid crystal is called ________. (a) lattice (b) buffer (c) atomic structure (d) configuration
26. Rare gases are stable because they ________. (a) are mono atomic (b) are volatile gases (c) have duplet or octet electronic configuration in the outermost shells of their atoms (d) have no neutrons in their nucleus
27. The bond type in a diatomic Nitrogen gas is _________ bond . (a) double covalent (b) triple covalent (c) single covalent (d) double electrovalent
28. An element belongs to a period in the periodic table because of _______. (a) the number of electrons in its outer-most shell (b) the shell number (c) the electronic configuration in the azimuthal quantum number (d) the size of the atom
29. The bond between a highly electronegative atom and a hydrogen from another molecule is called _________. (a) hydrogen bond (b) covalent bond (c) inter molecular forces (d) ligand
30. The bond between two iodine molecules is ________. (a) co-ordinate bond (b) electrovalent bond (c) ionic bond (d) van der Waal’s forces
Section B: Theory
Instruction: Answer any three (3) questions from this section.
1a. Define the term mixture and compound.
1b. Give three differences between them
1c. Classify the following substances as element, a mixture or a compound.
[ Limestone, clay, urea, diamond, sand urine, sugar, bronze, gold, iron, neon, air, milk, soap, soil]
2a. State three differences between physical and chemical changes
2b. Classify each of the following changes as either a physical or a chemical change.
i. The addition of water to quicklime (i.e. The slacking of lime)
ii. The melting of candle wax
iii. The change in colour of zinc oxide from white to yellow and vice versa during heating and after cooling respectively
iv. The dissolution of common salt in water
v. The dissolution of copper in concentrated trioxonitrate (V) acid
vi. The hardening of cement by absorption of carbon(IV) oxide
3a. Define the relative atomic mass of an element.
3b. Calculate the relative molecular mass of :
i. Slaked lime, Ca(OH)2
ii. Sodium trioxonitrate(V), NaNO3
3c. Find the empirical formula of the following compounds from their percentage composition by mass.
i. Ag = 63.53%; N = 8.23%; O = 28.24%
ii. N = 26.17% ; H = 7.48% ; CL = 66.35%.
4a. State the Law of Constant Composition (Definite Proportions)
4b Balance the following equations.
i. KCl3 ==> KCl + O2
ii. NH3 + O2 ==> H2O + N2
iii. Cu2S + O2 ==> Cu2O + SO2
4c. State Dalton’s theory about the atom.
5a. Write down the electronic configurations for the following elements using orbital diagrams:
i. Sodium =
ii. Sulphur =
iii. Chlorine =
iv. Argon =
5b. What are the types of bond present in each of the following compounds?
i. Carbon(IV) oxide
ii. Methane
iii. Ammonium chloride
iv. Calcium oxide
5c. What are isotopes?