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2019 WAEC GCE CHEMISTRY EXPO QUESTIONS AND ANSWERS

WAEC 2020 Expo

2019 WAEC GCE CHEMISTRY EXPO

2019 WAEC GCE Chemistry Questions Compiled By Olodo9ja to our amirable students.

1.    An element belongs to a period in the periodic table because of
(a) The number of electrons in the outermost shell
(b) The shell number
(c) The electronic configuration is the azimuthal quantum number
(d) The size of the atom.

2.    Rare gases are stable because they

(a) Are mono-atomic
(b) Are volatile gases
(c) Form ions easily
(d) Have duplet or octet electronic configurations in the outermost shells of the atoms.
3.    In electro-valency, valence electrons are transferred and the atomic number is (a) Also reduced
(b) Stabilized
(c) Unaffected
(d) Destabilized

4.    Mendeleev periodic table was arranged in order of their
(a) Atomic numbers
(b) Molecular shapes and orbitals
(c) Increasing relative atomic mass
(d) Orbital configuration

5.    S-block element of the periodic table are made up of
(a) Groups 1, 2, 3
(b) Groups land 2
(c) Groups 3
(d) Groups 3 to 7

6.    Energy required to remove the most loosely bound electron from a gaseous atom to form the gaseous ion is
(a) Gaseous energy
(b) Ionization energy
(c) Dissociation energy
(d) Atomization energy

7.    Element in the same group in the periodic table have the same
(a) Number of valence electrons
(b) Numbers of shells
(c) Atomic mass
(d) Atomic number

8.    Water exist as a solid, liquid and gas respectively because
(a) Water is colourless
(b) Water is electrovalent
(c) Water in any state processes a certain degree of motion in the molecules (d) Water is molecular
9.    According to kinetic theory, an increase in temperature causes the kinetic energy of particles to
(a) decrease
(b) increase
(c) be zero
(d) remain constant
10.    A gas exerts pressure on its container because ____
(a) some of its molecules are moving faster than other
(b) of the collision of the molecules with each other
(c) of the mass of molecules of gas
(d) the molecules of gs collide with walls of the container

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11.    An element belongs to a period in the periodic table because of
(a) The number of electrons in the outermost shell
(b) The shell number
(c) the electronic configuration in the azimuthal quantum number
(d) The size of the atom

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12.    The major reason why chemical reaction occurs among elements is that they have the tendency to
(a) Attain the nearest noble gas structure
(b) Become a metal (c) Become a non-metal
(d) Become any noble element

13.                                      2p
2s
1s

The above orbital diagram shows the electronic configuration of                            (a) Chlorine
(b) Nitrogen
(c) Neon
(d) Oxygen

14.    Which of these is the same in isotopes of element
(a) Mass number
(b) Number of neutrons
(c) Relative atomic man
(d) Atomic number

15.    There are basic particles from which matter could be made except                     (a) Salt
(b) Atom
(c) Ion
(d) Molecules

16.    Atomicity of oz(O2) is
(a) 1
(b) 2
(c) 3
(d) 4

17.    The modern standard element with which chemist define relative atomic mass is
(a) 12C
(b) 13C
(c) 3H
(d) 14C

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18.    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

19.    The empirical formula of C6H6 is
(a) CH
(b) C3H3
(c) C¬6H¬6
(d) 3CH

20.    3NH3 is
(a) 3 moles of ammonium
(b) 3 moles of ammonia
(c) 6 mole of ammonia
(d) 6 mole of ammonium

SECTION B (THEORY)

ANSWER ONLY FOUR (4) QUESTIONS. (show all rough works in your answer script).

1.    Balance the following equations.
i.    H2(g)   +   O2(g)         2H2(g)
ii.    Mg    +    HCL        Mgcl2  +    H2
2.    Write the electronic configuration of the following elements
i.    Na     ii. K    iii. Cl        iv. Ca        v. C
3.    Write down the names of the following compounds;
i.    Nacl    ii. Hcl        iii. H2SO4
4.    State the following laws with their formular
(i) boyle’s law
(ii) charle’s law
(iii) General gas equation
(v) Avogadro’s law
5.    Calculate the volume of oxygen at 250c and 745 mmhg pressure which could be obtained by heating log of potassium trioxodiulorate(v) (pb + 207, N = 14, o= 16, molar volume of gases at s.t.p = 22.4dm3) required to convert
6.    Find the number of molecules of oxygen 6.60dm3 of S02, measured at s.t.p = 220.4dm3 Avogadro’s number = 6.02 x 1023 particles per mole
Section B
7.    Define the following: (i) Mixture (ii) sublimation (iii) fine chemicals
8.    (a) Differentiate between heavy chemical and fine chemical
(b) Give two (2) examples each
9.    List and explain five(s) career opportunities attached to the knowledge of chemistry
10.    (a) explain fractional distillation
(b) List five(5) differences between evaporation and boiling

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