CHEMISTRY QUESTION AND SOLUTION FOR 2017/2018

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  2ai) – Oxidation is a process involving on loss of electrons

  • Reduction is a process Involving the removal at electronegative elements as well as the addition of electro positive elements
    2aii) – Nitrogen is a colourless,odourless and tasteless gas

  • it is slightly lighter than air
    2aiii) X represents urea [(NH2)2Co)]

  • Y represents water[H2o]
    2ciii) Polymerization is the process whereby two or more monomers link together to form a compound of high molecular mass called the polymer

*

2civ) – It is used as a fuel in rockets

  • It is sometimes uses as an anti-freeze

-it is used to dissolve soaps,perfumes etc

CHEMISTRY SOLUTIONS*
1ai)-Boiling Point and Freezing Point.

-Surface Tension, Heat of Vaporization,volume

apor Pressure.
1aii) [Na]/[Na2So4] × 100%

23/(23×2)+32+(16×4) × 100%

23/142 × 100%

=16.2%

Percentage by mass of sodium=16.2%

Also,

[O4]/[Na2So4] × 100%

4×16/142 × 100%

64/142 × 100℅

=45.1℅

Percentage by mass of oxygen=45.1%
1aiii)- Aluminium
1aiv)bauxite
1bi)-A

-D

-C

-E

-B
1bii) A standard solution is a solution containing a precisely known concentration of an element or a substance. A known weight of solute is dissolved to make a specific volume. It is prepared using a

standard subs as a primary

standard.
1biii)-A dilute solution contains a smaller amount of solute than does a concentrated solution

  • A dilute solution contains more solvent than an equal volume of

concentrated solution does.
1ci)- monosaccharides 

-disaccharides 
1cii) DRAW TJE STRUCTURAL FORMULA
1ciii) A lighted wooden splint goes out in a

test tube of carbon dioxide but this happens with other gases, too. It is better to bubble the test gas through limewater – calcium hydroxide solution. Carbon dioxide turns limewater cloudy white.

==================

2ai) – Oxidation is a process involving on loss of electrons

  • Reduction is a process involving the removal at electronegative elements as well as the addition of electro positive elements
    2aii) – Nitrogen is a colourless,odourless and tasteless gas

  • it is slightly lighter than air
    2aiii) X represents urea [(NH2)2Co)]

  • Y represents water[H2o]
    2bi) 

Chlorine|35|17|18|1s^2 2s^2 2p^6 3s^2 3p^5

Fluorine|18|9|10|1s^2 2s^2 2p^5
2bii) No of moles= Mass/Molarmass

=5/25+16+1

=5/40

No of moles=0.125mole
2biii) Relative atomic Mass= 

(18 × 1/3) + (20 × 2/3)

=19.3
2ci)Faraday’s second law of electrolysis states that, when the same quantity of electricity is passed through several electrolytes, the mass of the substances deposited are proportional to their respective chemical equivalent or equivalent weight.
2cii) Single line represents the electrode/electrolyte reaction

  • Double lines represents interface in the full cell
    2ciii) Polymerization is the process whereby two or more monomers link together to form a compound of high molecular mass called the polymer
    2civ) – It is used as a fuel in rockets

  • It is sometimes uses as an anti-freeze

-it is used to dissolve soaps,perfumes etc

3ai)

i) Metals differ so widely in hardness, ductility (the potentiality of being drawn into wire), malleability, tensile strength, density, and melting point. 
ii) Mercury is liquid at room temperature and gallium melts on our hand while tungsten has a melting point of 3687K (3414 0C)

iii) Most metals are highly lustrous (they shine very brightly) and sonorous (they produce sound when struck)

5a) Peroxide are oxides containing a higher proportion of oxygen than the ordinary oxides 
ii)-Sodium Peroxide Na2O2

-Hydogen Peroxide H2O2

-Barium Peroxide Ba2O

-Calcium Peroxide CaO2
Iii)

 II)The Ionic Polar Head of Soap Molecules that are responsible for it solubility 

III) In acidic Water it react with excess Hydogen ions to form unionized fatty Acids
iv) Biodegradibility of Soap Molecules means that Soap can easily be decomposed by bacteria into simple inorganic substances, so it does not cause Water Pollution

5ci) Boyle’s law states that at constant temperature for a fixed mass, the absolute pressure and the volume of a gas are inversely proportional. The law can also be stated in a slightly different manner, that the product of absolute pressure and volume is always constant.

[7/6, 9:45 AM] Master ExM: CHEMISTRY SOLUTIONS
1ai)-Boiling Point and Freezing Point.

-Surface Tension, Heat of Vaporization,volume

apor Pressure.
1aii) [Na]/[Na2So4] × 100%

23/(23×2)+32+(16×4) × 100%

23/142 × 100%

=16.2%

Percentage by mass of sodium=16.2%

Also,

[O4]/[Na2So4] × 100%

4×16/142 × 100%

64/142 × 100℅

=45.1℅

Percentage by mass of oxygen=45.1%
1aiii)- Aluminium
1aiv)bauxite
1bi)-A

-D

-C

-E

-B
1bii) A standard solution is a solution containing a precisely known concentration of an element or a substance. A known weight of solute is dissolved to make a specific volume. It is prepared using a

standard subs as a primary

standard.
1biii)-A dilute solution contains a smaller amount of solute than does a concentrated solution

  • A dilute solution contains more solvent than an equal volume of

concentrated solution does.
1ci)- monosaccharides 

-disaccharides 
1cii) DRAW TJE STRUCTURAL FORMULA
1ciii) A lighted wooden splint goes out in a

test tube of carbon dioxide but this happens with other gases, too. It is better to bubble the test gas through limewater – calcium hydroxide solution. Carbon dioxide turns limewater cloudy white.

==================

2ai) – Oxidation is a process involving on loss of electrons

  • Reduction is a process involving the removal at electronegative elements as well as the addition of electro positive elements
    2aii) – Nitrogen is a colourless,odourless and tasteless gas

  • it is slightly lighter than air
    2aiii) X represents urea [(NH2)2Co)]

  • Y represents water[H2o]
    2bi) 

Chlorine|35|17|18|1s^2 2s^2 2p^6 3s^2 3p^5

Fluorine|18|9|10|1s^2 2s^2 2p^5
2bii) No of moles= Mass/Molarmass

=5/25+16+1

=5/40

No of moles=0.125mole
2biii) Relative atomic Mass= 

(18 × 1/3) + (20 × 2/3)

=19.3
2ci)Faraday’s second law of electrolysis states that, when the same quantity of electricity is passed through several electrolytes, the mass of the substances deposited are proportional to their respective chemical equivalent or equivalent weight.
2cii) Single line represents the electrode/electrolyte reaction

  • Double lines represents interface in the full cell
    2ciii) Polymerization is the process whereby two or more monomers link together to form a compound of high molecular mass called the polymer
    2civ) – It is used as a fuel in rockets

  • It is sometimes uses as an anti-freeze

-it is used to dissolve soaps,perfumes etc

3ai)

i) Metals differ so widely in hardness, ductility (the potentiality of being drawn into wire), malleability, tensile strength, density, and melting point. 
ii) Mercury is liquid at room temperature and gallium melts on our hand while tungsten has a melting point of 3687K (3414 0C)

iii) Most metals are highly lustrous (they shine very brightly) and sonorous (they produce sound when struck)

5a) Peroxide are oxides containing a higher proportion of oxygen than the ordinary oxides 
ii)-Sodium Peroxide Na2O2

-Hydogen Peroxide H2O2

-Barium Peroxide Ba2O

-Calcium Peroxide CaO2
Iii)

 II)The Ionic Polar Head of Soap Molecules that are responsible for it solubility 

III) In acidic Water it react with excess Hydogen ions to form unionized fatty Acids
iv) Biodegradibility of Soap Molecules means that Soap can easily be decomposed by bacteria into simple inorganic substances, so it does not cause Water Pollution

5ci) Boyle’s law states that at constant temperature for a fixed mass, the absolute pressure and the volume of a gas are inversely proportional. The law can also be stated in a slightly different manner, that the product of absolute pressure and volume is always constant.

6ai)

I)solution A is starch solution, sample B is Iodine

II)the colouration is formed due to the formation of an Iodine starch complex

III)

i)Iodine is used in treatment of goitre

ii)Iodine is used in making dye for colour photography

6aii)

dalton’s law of partial pressure states that in a mixture of non-reacting gases, the total pressureexerted is equal to the sum of the partial pressuresof the individual gases.

6bi)

C – 4.08/12, H – 0.68/1, O – 5.46/16

0.34/0.34, 0.68/034, 0.34/0.34

1, 2, 1.

The emperical formula is CH2O

6bii)

( CH2O)n =60

((121)+(12)+(16*1))n=60

(12+2+16)n=60

30n/30=60/30

n=2

(CH2O)2=C2H4O2

the molecular formular is C2H202

6ci)

i)exothermic reaction

ii)A is activation energy, B is DH(Negative)

6cii)

i)removeal of carbon(iv)oxide

ii)liquetying the air

6ciii)

vander waal forces

6di)

fats have higher melting point than oil because fats are more denser

6dii)

i)it is poisonous

ii)it is 2,5 times denser than air

iii)it is greenish-yellow gas with a choking smell

6diii)

Zn^2+ has comppletely filled d-orbitals and there are no vacant d-orbitals for the transition of electrons while Sc^3+ has completely empty d-orbital and there are no electrons for d-d transition thus they are colourless

​CHEMISTRY OBJ​ BY GistNaira TeaM

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