2017/2018 Neco Gce Chemistry Obj And Theory Now Out



In a tabular form
C; H; O
Mass/molar mass of C is 6.12g/12
Mass/molar mass of H is 0.85g/1
Mass/molar mass of O is 2.72/16

Under C: 0.51
Under H: 0.85
Under O: 0.17

C = 0.51/0.17
H = 0.85/0.17
O = 0.17/0.17

Empirical Formula is C3H5O
Molecular Formula is. ?
Molar mass is 134
[C3H5O]n = 134
[12 × 3 + 1×5 + 16 × 1]n = 134
[36 + 5 + 16]n = 134
57n = 134
n = 134/57
n = 2.35
n = 2
Molecular Formula [C3H5O]2
= C6H10O2

Isotopy – Atom of the same element are alike in every aspect and differ from atoms of all other element
17Cl and


Sub atomic particle: All elements are made up of small indivisible particles called atoms


I. 2C2H2 + 5O2 —> 4CO2 + 2H2O
II. C2H2 + HCl —> C2H3Cl

Because they are in different states. Steam is in a gaseous state while water is in a liquid state.

(i) Temporary hardness – Dissolved calcium
(ii) Permanent hardness -Dissolved calcium sulfate.
(i) Temporary Hardness can be Removed By Boiling
(ii) Permanent hardness can be removed by use of
washing soda (sodium carbonate); ion exchange; the
use of polyphosphate water softeners.
(i) Calcium ions in the water are good for children’s teeth
and bones.
(ii) The soothe it forms is good for ceramics purposes.
(i) It is more difficult to form a lather with soap.
(ii) Scum may form in a reaction with soap, wasting the
A saturated solution is a chemical solution containing
the maximum concentration of a solute dissolved in the

Mass of impure CaCo3 = 5.2g
Amount n; of CO2 formed = 0.05moles
CaCo3 + 2Hcl —> Cacl2 + CO2 + H2O
1 mole of CaCo3 = 1 mole of Co2
100g of CaCo3 = 1 mole of Co2
Hence Xg of CaCo3 = 0.05mole CO2
X = 0.05 × 1/1 = 0.05mol of CaCo3
but n = m/M
Therefore; m = nM = 0.05 × 100
=5g of CaCo3
%purity of CaCo3
= mass of pure/mass of impure × 100/1
= 5/5.2 × 100/1 = 96.2%

(i) Anthracite Coal
(ii) Bituminous coal
(iii) Subbituminous coal
Coal tar
(i) Zinc is not a transition metal because it forms only
Zn2+ ions with all the 3d electrons present.
(ii) Zn not a transition metal, because it forms only Sc3+
ions with n d-electrons
Fine chemicalChemical substances prepared to a very
high degree of purity for use in research and industry.
(i) dyes
(ii) perfumes

Homogenous mixture is a mixture that is composed in equal amount of proportions .. eg CaCo3

Heterogenous is when it’s unequal eg floodwater

Molar mass = 2×VD
The atomic mass of x is 31g

Petroleum Gas and Petrol>Kerosene>Diesel>Asphalt

I. Asphalt
II. Kerosene
III. Petroleum Gas and petrol
Iv. Asphalt

I. Ethene
II. Propene

(i) Structural Isomerism
(ii) Stereo Isomerism

19R – 1s² 2s² 2p6 3s² 3p6 4s¹
10S – 1s² 2s² 2p6
24T – 1s² 2s² 2p6 3s² 3p6 4s² 3d4

Group 6

I. AgNO3 and BaCl2
II. Bacl2 and Na2SO4
III. Ca(NO3)2 and H2CO3

(i) Filtration
(ii) Flocculation
(iii) Disinfection

Mass of NaCl
= mass of Nacl + mass of H2O
= (23 + 35.5) + 80g
= 58.5 + 80g = 138.5g
Since 39.8g at 100°C = 35.9g at 15°C
138.5g at 100°C = Xg at 15°C
X = 138.5 × 35.9/39.8g
= 124.9g at 15°C
Hence mass of Nacl precipitated
= 138.5 – 124.9g
= 13.6g of Nacl

(i) Coke
(ii) Graphite
(iii) Diamond
(iv) Coal
(v) Charcoal

Le chatelier’s principle states that for a reversible reaction in equilibrium, if any of the factors(temperature, concentration, pressure) keeping the system in equilibrium is altered, the system will shift to adjust the change

I – It will shift from left to right
II – It will shift from left to right
III – It will favor the forward reaction by increasing the product

Kc = [NH]2
4H2O + 3Fe —> Fe3O4 + 4H2
3 moles of Me = 4 moles of H2
3(56)g = 4(22.4dm³) of H2
Therefore; 3.03g of Fe = Xg of H2
X = 3.03 × 4 × 22.4dm³/3 × 56
= 1.62dm³ of H2

3(56)g of Fe = 3(56) + 4(16)g
Therefore; 3.03g of Fe = X
X = 3.03 × 232/168 × 1 = 4.18g of iron oxide

i) increasing the surface area
By adding catalyst to the reaction

If 100g of Caco3—–1mole of co2(22.4dm3)

:.0.896dm^3 of CO2 was produced by 4g of Caco3

17. Normal salt…. Na2co3
Acid salt… NaHSO4
Complex salt…Ca3[Co(Cl)6]2

Be the first to comment

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.