NECO Chemistry 2017 Theory & Obj Essay | Expo Questions & Answers

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NECO Chemistry 2017 Theory & Obj Essay | Expo Questions & Answers

NECO Chemistry 2017 Theory & Obj Essay

Complete Chemistry 2017 Theory & Obj Essay Expo Questions & Answers: Presently, this article contains the NECO Past Chemistry 2017 Objectives & Theory answers released online for students looking for simple guidelines to pass the upcoming Chemistry exam scheduled by National Examination Council to take place next week Thursday.

Furthermore, it can be recalled that we published an article the previous month on NECO Past Chemistry Specimen & Practical 2017 past questions and answers to help students preparing to participate NECO practical. Afterwords, we received hundreds of feedback from students appreciating the guide we wrote online. Note that is is not an expo/runz.

Additionally, the Objectives and Theory/Essay NECO Chemistry 2017 Answers cannot be seen online until the exam has be completely written. However, samples questions and answer has been published on this page to guide people who are serious minded and wants to use it to read their books.

Chemistry (OBJ And ESSAY) NECO 2017 Free Expo Answers

WARNING: Above all, This is not the current NECO exam answers 2017. DO not use it as expo for examination malpractice because you will fail. Its for study purpose only.

Thursday 18th April 2016

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CHEMISTRY 2 (ESSAY) 2.00PM – 4.00PM

CHEMISTRY 1 (OBJ) 4.00PM – 5.00PM

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NECO Chemistry Objective Answer

1-10 CAACDBCABC

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11-20 BDBABBBDCA

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21-30 BCCABBCACB

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31-40 AACDCCCBBA

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41-50 ABCBBABBBB

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NECO Chemistry Theory/Essay Answer

Question 1

1a )

nucleons is the collective name for two important sub-atomic particles : neutrons and protons

1b)

Graham ‘s law of diffusion states that at a constant temperature and presure , the rate of

diffusion of a gas is inversely proportional to the square root of it density

1c )

because when aluminum is exposed to moist air, a thin continuous coating of aluminum oxide

is formed , which prevents futher attack of the aluminium by atmospheric oxygen and water or

steam under normal conditions 

1d)

  • i ) electron – affinity
  • ii ) electron – negativity
  • iii ) ionization – energy

1e )

  • i ) the molecule of real gases occupies space and there are forces of the attraction between them
  • ii ) real gases do liquefy when their temperature droops .

1f )

  • i ) used in separation of different component of crude oil .
  • ii ) it is used for separating acetonic from water
  • iii ) it is used for obtaining different gases from air for industrial use .

1g)

  • i ) concentration of ions in electrolyte
  • ii )the nature of the electrode
  • iii )the position of ions in the electro chemical series

1h)

  • i ) substitution reaction
  • ii )addition reaction

1i )

  • i ) carbon dioxide
  • ii )water vapour
  • iii ) carbon monoxide

1j )

  • i ) centrifugation
  • ii )sieving
  • iii )evaporation to dryness

Question 2

2a) 

i ) isotopy

ii ) they have the same number of proton (atomic

number) but different mass number

iii ) oxygen ,carbon

iv )1s ^2, 2s ^2, 2p^6 ,3 s ^2, 3p^5

2bi)

PHYSICAL PROPERTIES METAL

  • i ) high melting and boiling point
  • ii ) they are good conductor of heat and electricity

NON -MATEL

  • i ) they have lower melting and boiling point
  • ii ) they are poor conductors of heat and electricity .

CHEMICAL PROPERTIES METAL – NECO CHEMISTRY

  • i ) they form basic and ampheric oxides
  • ii )the react by electron lose or donation of electron

NON -METAL

  • i ) the form acidic oxides
  • ii )the react by sharing and accepting electrons

2bii )

  • i ) Al 2 O 3(Aluminum oxide )
  • ii ) sodium hydride (NaH )
  • iii ) zinc trioxocarbonate( iv )ZnCo 3
  • iv ) silicon tetrachloride (SiCl 4)

2ci )

  • i ) variable oxidation states
  • ii ) complex ion formation
  • iii ) they possess strong metallic bonding

2cii )

  • 1s ^2, 2s ^2, 2p^6 , 3s ^2, 3p^6, 3 d^10, 4 s ^2

2ciii )

Zinc is not considered as a typical transition element bacause it has only one oxidation state of +2 , it metallic ion are not coloured and it is not used as a catalyst.

2d)

Na 2Co 3 + MgCl 2 — — > 2NaCl + MgCo 3

1mole 1mole 2 mole 1mole

molar mass of Na 2 Co 3 = 2 * 23 + 12 * 1 + 16 *

3 = 46+ 12+48 = 106g

Question 3

3ai)

Structral isomerism is the existence of two or more compounds ( known as isomers) with the same molecular formula but different molecular structures

3ai)

  • i) tertiary alkanol
  • ii) secondary alkanol
  • iii) primary alkanol

3bi)

  • i) 2[CH3 CH2 COOH ] 2K(s)
  • ii) [CH3 CH2 COO ] K + H2

i) 2[CH3 CH2 COOH ] +2 K(s) ——> 2[ CH3 CH2 COO ] K + H2

ii) CH3 CH2 COOH + C4 H9OH HEAT—->CH3 CH2 COO C4 H9 + H20 H2SO4

iii)CH3 CH2 CH2 CH20H + H^+KMnO4——> CH3 CH2 CH2 CH2 – 0H EXCESS

3bii)

  • i) potassium ethanoate,hydrogen
  • ii) butyl propanoate and water
  • iii) enthanal

3c)

the percentage composition of the hydrocarbon = 100

H + C = 100

14.3 + C =100

C= 100 – 14.3

C= 85.7%

NECO Chemistry 2017 Theory & Obj Essay

Question 4

(4ai) calcium chloride, CaCl2

(4aii) To the unknown ssubstance in a gas jar, add small quantity of lime water. if the gas is carbon(iv)oxide, it turns lime water milky while carbon (ii) oxide has no effect

(4bi) Oxygen is releasedf abundantly from air and nitrogen is produced by the reaction of potassium trioxonitrate(v) with concentrated hydrochloric acid

(4bii) Oxygen gas rekindle a lighted splint while nitrogen does not

(4ci) Bauxite is preferred because it is readily available in the earth crust

(4cii) Trioxosilicate and carbon(iv)oxide

(4ciii) It helps to purify the bauxite

(4civ) It is difficult to extract aluminium by chemical reduction of aluminium oxide in amphoteric

(4cv) – AL2O3+NaOH=>Na2O + Al+ H20

Question 5

5ai )

Na 2S 2O 3 ===> 2 + 2x + 6 = 0

2x = 6 – 2 = 4

X = 4/2

X = 2

The oxidation number of sulphur is 2

5aii ) Rhombic & monoclinic

5aiii )

  • – Both are tetravalent
  • – both are allotrope of carbon

5bi) CO2 & Chloroflorocarbon

5bii ) There is increase in sun radiation reaching the earths surface ie Global warming

5biii )ThunderStorm

5iv )

I 2KNo 3. – — – — — > 2KNO3 + O 2

2AgNo 3 — — – — — > . 2Ag + 2No

5ci ) Calcium chloride in a solution can give rise to crystal using filteration & evaporation to dryness. The sol is filtered into filtrate & residue before evaporation to dryness takes place .

5cii )

  • – Because of presence of hydrogen bonding in NH 3
  • – Because Iodine as higher molecular mass than chlorine

5di)

Mol of Nacl = Mass / MM

= 5 . 85/ 58. 01

= 0 . 1mol

From the equation 2mol of Nacl gives 2mol of HCL, 0. 1mol of Nacl gives 0. 1mol of Hcl

Vol of Hcl = 0. 1 x 22. 4 = 2. 24mol /dm^3

Question 8

(8ai) Each successive member of a homologous series differ by ~CH2~group.Members of a homologous series show similar chemical properties.

(8biii) C2H5OH +CH3CH2COOH=CH3CH2COOC2H5 ethylpropanoate

(8biii) C2H5OH+CH3CH2COOH=CH3CH2COOC2H5 ethylpropanoate

(8ai) Each successive member of a homologous series differ by ~CH2~group.Members of a homologous series show similar chemical properties.

(8biii) C2H5OH +CH3CH2COOH=CH3CH2COOC2H5 ethylpropanoate.

(8ai) Each successive member of a homologous series differ by ~CH2~group.Members of a homologous series show similar chemical properties.

(8biii) C2H5OH+CH3CH2COOH=CH3CH2COOC2H5 ethylpropanoate

(8biii) C2H5OH+CH3CH2COOH=CH3CH2COOC2H5 ethylpropanoate

(8ai) Each successive member of a homologous series differ by ~CH2~group.Members of a homologous series show similar chemical properties.

(8biii)C2H5OH + CH3CH2COOH = CH3CH2COOC2H5 ethylpropanoate.

=====NECO PAST QUESTIONS AND ANSWER COMPLETED=====

NECO Chemistry 2017 Theory & Obj Essay

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