NECO Chemistry Past Questions & Answer 2017 | Essay & Objectives Theory
Firstly, this is the Past NECO Chemistry 2017 Objectives & Theory answers published for students who is searching for guidelines to pass the upcoming Chemistry examination scheduled for next week.
Sometime last month we published an article on Past NECO Chemistry Practical Specimen 2017 for students writing NECO practical and thousands of students sent us mail to thank us for giving out past questions which they studied before writing the exam.
Similarly, the Essay & Objectives Theory NECO Chemistry 2017 answers has been published on this page to assist students who wants to use it to study.
WARNING: 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.
Date for Writing NECO Chemistry Exam 2017
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Chemistry 2 (Essay) Thursday 6th July: 10am - 1pm
Chemistry 1 (Objective) Thursday 6th July: 10am - 1pm
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Chemistry Past Obj Answers: No Questions at all
01 - 10 = ACDBCBDBCA11 - 10 = DBAADCDBCB21 - 20 = DBCBCCDBAD31 - 30 = BACBACBCCD41 - 50 = BDACABDABD
Chemistry Past Theory Answer: The Questions are not Here
Question 3
1ai) An acid base indicator is a weak acid or weak base that exhibits a colour change as the concentration of hydrogen (H^+) or hydroxide (H^-) ions changes in an aqueous solution
1aii) Methyl-orange
1b)
i) Oxidizing agent
ii) Mixed anhydride
1ci)
Enthalpy of combustion is the heat evolved when one mole of a substance is completely burns in oxygen gas under standard conditions
1cii)
Enthapy of combustion is always negetive since it involvs a rise in temperature and heat of reactants is greater than the heat of products
1d)
Primary cell is a cell that cannot be re charged while secondary cell is a cell that can be recharged
1dii)
primary cell -- daniell cell
secondary cell -- lead accumulator
1e)
Mole is the unit of measurement in the International System of Units (SI) for amount of substance. The unit is defined as the amount of a chemical substance which contains as many representative particles, e.g., atoms, molecules, ions, electrons, or photons, as there are atoms in 12 grams of carbon-12 (12C), the isotope of carbon with relative atomic mass
1f)
n= V=40cm^3
c= 0.40moldm^3
n=cv/1000
0.40*40/1000 = 0.016mol
1g)
i) Platinum
ii) Carbon
1h)
i) Hydrogen bonds
ii) Vander waals forces
1i) Water(H2O) and Carbonmonoxide (Co)
1j) 1s^2 2s^2 2p^6 3s^2 3p^6 3d^3 4s^2
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Question 3
3b)
In other words the oil is stained red. This is a specific test for fats if suden (iii) is added to fats a distinct red colouration is observed
3c)
Given 2502+02+2H20--->2H2SO4
1mole produce 2mole
1.3mole produce 3mole
moles of H2SO4=3mole
molar mass of H2SO4=(1+2)+32+(4*16)
=2+32+64 = 98gmol-^1
mole=mass/molar mass
mass and H2SO4=Mole*molar mass
=3*98 =294g
3di) DH2
Question 4
4ai) Thermal cracking
4aii) C4H8
4aiii)
(I) H H. H
| | |
H-C-C-C=C
| | | |
H H H H
and
(II) H H
| |
H-C-C=C-C-H
| | | |
H H H H
4aiv)
I-normal butene
II -But-2-ene
Ni
4av)
C4H8 +H2 -------> C4H10
250c
4b)
method
- rub the fat on a blank white paper
- pour Sudan (III) dye over the paper
-wash the paper under tap
Observation
- rubbing the fat on the paper produces a translucent color
-pouring sudan (III) will stain the blot red
Conclusion
- fat is present because sudan (III) can stain fat red
Question 5
5bi)
C(s) + O2(g) =====> Co2(g)
Co2(g) + C(s) =====> 2Co(g)
Fe2O3(s) + 3Co(g) =====> 2Fe(l) + 3Co2(g)
The limestone present decomposes as follows:
CaCo3(s) =====> CaO(s) + Co2(g)
Which is available to remove silicon(iv) oxide impurity
SiO2(s) + CaO(s) =====> CaSiO3(s)
5bii)
Faraday’s first law of electrolysis states that, the mass (m) of an element discharged during an electrolysis is directly proportional to the quantity of electricity (Q) passing through it.
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