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Neco 2017 Chemistry Obj And Theory Answers – May/June Expo

By | On July 5, 2017 (1 month ago)

CHEMISTRY THEORY ANSWERS


COMPLETED SOLUTION 

FROM STUDENTCLUB

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CHEMISTRY OBJ​

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1-10ACBAEDCCAB


 11-20ECACDCADBC


21-30ECCEBADADB


31-40CABEBBABEA


4159DDDBAABDEB


51-60-CEEEEECBDA

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CHEMISTRY THEORY

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1ai)

i)neutral to Litmus paper

ii)Has a boiling point of 100°C 


1aii)

=[Na] / [Na2So4]  × 100%

=23/ (23×2) +32+ (16×4)  × 100%

=23/142 × 100%

=16.2%

Percentage of mass of a sodium 

=16.2%

Also, 

[O4] /[Na2SO4]  × 100%

=(4×16) / 142 × 100%

=64/142 × 100%

=45.1%

Percentage of mass of oxygen 

=45.1


1aiii)

-Aluminum 

1iv)

-Bauxite (Al2O3 +2H2O)


1bi)

I = (A) Is2 , 2s2 ,2p2

II= (B) Is2 , 2s2, 2p6,3s2

III=(C) Is2, 2s2, 2p6

IV=(D) Is2 ,2s2, 2p6, 3s2,3p5

V=(E)  Is2, 2s2, 2p4


1bi)

A Standard solution is a solution of known concentration.it is a solution containing known amount (in grams or mols) of a substance in a known volume of a solution. 


1bii)

A concentrated solution contains lesser molecule of water than a dilute solution

 

1Ci)

i)simple sugar

ii) complex sugar


1cii) diagram(coming as image) 


1ciii)

Insert a glowing splinter into a test tube containing the unknown gas the rekindling of the glowing splinter indicates the presence of oxygen


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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]


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.


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

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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)

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4ai )

i ) addition of soda

ii) addition of zeolite

4aii )

the solubility of KCl increase at a constant rate with the rise in temperature while the solubility of NaCl is independent of temperature

4aiii )

PH of a solution is measure of the molar concentration of hydrogen ions in the solution

4aiv )

i ) A is most acidic

ii) E is most basic

iii ) C is neutral

4bi )

i ) gases are made up of molecules which are in constant random motion

ii) the particles do not attract each other

iii ) during motion the molecules of the gas collides with one another and with the wallss of container

4bii)

given that

P 1 = 320MMHg

P 2 = 760MMHg

V 1 = 220Cm ^ 3

V 2 =?

T 1 = 22degree

T 2 = 100degree

using P 1V 1/ T 1= P 2V 2/ T 2

V 2 = 320* 220 * 100 / 22* 760

V 2 = 7040000 / 16720

V 2 = 421. 05cm ^ 3

4ci )

Daigram

Loading .

4cii )

i ) it is used for respiration

ii) it is used in industries for removal of carbon sulphur and impurities in pig iron

iii ) oxygen is used as propelants in space rocket .

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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



  ( 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.

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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

((12*1)+(1*2)+(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

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Neco 2017 Chemistry QUESTION AND ANSWERS NOW 100% AVAILABLE WITH US. MAKE PAYMENT BELOW AND GET IT!!! Direct SMS: N500 MTN CARD (Full Answers Comes Direct To Your Phone As SMS/Text Message) Link/Pin: N300 MTN CARD (Pin To Access Our Answers Immediately After Subscription Will Be Sent To You) SEND: MTN CARDS, SUBJECT NAME AND PHONE NUMBER TO 09075552707 Answers/Password Will Come To Your Phone Before Exam Time. No Doubt About It. Pay And Enjoy Our Services NOTE:- All SMS Sent To The Above Number Are Attended To, Our Phone Number Might Be Diverted To Avoid Distraction. Always Send Us SMS Of Your Complaint Even When Our Number Is Diverted Or Not Available, Your Message(s) Will Get To Us And We Will Reply You ASAP.

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