# Ondo State Joint Chemistry Answers 2021

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OBJ:
01-10: BDACDBDACA
31-40:ABDDBBBDAC
Completed.!
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THEORY!

(1)
2HCL + Na2CO3 –––> 2Nacl + CO2 + H2O

TABULATE
Final burette Reading (cm³) | Rough 24.00 | First 22.50 | Second 23.00 | Third 23.10

initial Burette Reading (cm³) | Rough 0.00 | First 0.00 | Second 0.00 | Third 0.00 |

Volume of Acid used (cm³) | Rough 24.00 | First 22.50 | Second 23.00 | Third 23.10

*NOTE: ENSURE YOU USE YOUR SCHOOL TITRE VALUE AND VOLUME OF ACID USED*

(1ai)
25cm³

(1aii)
Methyl Orange

(1bi)
b=22.50-0.00
b=22.50cm³

a=23.00 – 23.00
a=0
c=23.10 – 0.00
c=23.10cm³

(1bii)
Average Titre Value = 2nd Titre Value + 3rd Titre Value ÷ 2
= 23.00 + 23.10 ÷ 2
= 23.05cm³

Therefore, Average Titre Value, VA = 23.05cm³

CA=?, CB=?, VA=23.05cm³, VB=25cm³

Mass of A = 3g/dm³
Molar Mass Of A = H + Cl = 1 + 35.5
Molar Mass of A = 36.5g/Mol

Molar Concentration = Mass Concentration ÷ Molar Mass
= 3 ÷ 36.5
= 0.0822mol/dm³
:. CA = 0.0822mol/dm³

(1biii)
CAVA/CBVB = nA/nB
Where nA = 2 , nB = 1, CB =?, CA = 0.0822mol/dm³ , VB = 25

===> 0.0822 × 23.05 ÷ CB × 25 = 2/1
CB = 0.0822 × 23.05 ÷ 2 × 25
CB = 1.8947 ÷ 50
CB = 0.0379Mol/dm³

(1ci)
(i) Beaker
(ii) Separating funnel
(iv) Pipette
(v) Burette

(i) Beaker:- This is used to hold liquids in the laboratory for liquid

(ii) Separating funnel:- This is used in the laboratory for Liquid Extractions, It is Precisely used to separate a mixture of two solvents of different densities.

(iii) Conical Flask:- This is used for holding And Measuring Chemical Liquid Samples.

(iv) Pipette:- This is used to measure out Or transfer Small Quantities of liquids.

(v) Burette:- This is used during quantitative analysis to measure the volume of a given liquid or gas.

(1cii)
(Pick Any five)
(i) Obey safety Rules
(ii) Dress Properly
(iii) Handle Corrosive chemicals with extreme care
(iv) Do not mix chemical carelessly
(v) Seek the guidance of the lab attendant if you are in doubt of any mixture you want to carry out
(vi) Do not taste or sniff Chemicals
(vii) Identify Safety Equipment
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(5ai)
Definition of water pollution. Water pollution is the release or injection of substances into the water bodies in quantities or level that are harmful to man, animals and plants.

(5aii)
(Pick any four)
(i) Domestic waste/sewage/household waste.
(iii) Agricultural wastes/pesticides/insecticides/fertilizers.
(iv) Oil spillage.
(v) Hot water/thermal plants.

(5aiii)
(Pick any Five)
(i)Proper legislation on use of water bodies.
(ii) Avoid dumping of untreated wastes into the waters.
(iii) Public enlightenment.
(iv) Good fishing practices.
(v) Providing public utilities e.g. toilets, incinerators, etc.
(vi) Treatment of industrial waste.

(5bi)
(i) Yellow Rhombic Sulphur (α-sulphur).
(ii) Monoclinic Sulphur (β-sulphur).

(5bii)
(i) Rhombic sulphur exists as rhombic octahedral crystals whereas Monoclinic sulphur exists as long, needle-shape prisms.
(ii) Rhombic sulphur the S8 molecules fit tightly into each other, whereas in Monoclinic sulphur, the S8 molecules are piled up on top of each other.
(iii) Rhombic sulphur is stable below 96°C whereas Monoclinic sulphur is stable above 96°C.
(iv) Rhombic sulphur is bright in yellow in colour while; Monoclinic Sulphur is dull yellow in colour.
(v) Rhombic sulphur has low thermal and electrical conductivity while; Monoclinic Sulphur has high thermal and electrical conductivity.

(5c)
(i) Purification of some metals.
(ii) Electrolysis is used in production of gases, e.g. Hydrogen from water.
(iii) Used in extraction of some metals from their ores, e.g. Aluminium from bauxite.
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(3ai)
Graham’s law of diffusion states that the rate of diffusion of a gas is inversely proportional to the square root of its vapour density.

(3aii)
Check the diagram

(3ci)
(i)Covalent bond.
(ii)Dative or Co-ordinate covalent bond.

(3cii)
-(Choose any 3)-
(i)They have high melting point or boiling point.
(ii)They conduct electricity when molten or in solution.
(iii)They exist as aggregates of ions.
(iv)They are soluble in polar solvent e.g water and insoluble in non-polar solvents.
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(2ai)
Basicity of an acid is defined as the number of replaceable hydrogen atom of the same acid by a base

(2aii)
TABULATE

MONOBASIC
HCL
CH3COOH

DIBASIC
H2SO4
———-

TRIBASIC
H3PO4
———-

(2b)
(i) Lactic Acid ——> Milk
(ii) Absorbic ——> Orange (Citrus Fruit)
(iii) Amino Acid ——> Meat, Beans, Fish, Eggs (Pick one)
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Completed.!
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