NECO Past Questions

NECO Chemistry Practical Questions and Answers | –Download PDF. The National Examination Council of Nigeria (NECO) Examination is around the corner. This article provides the readers with the information on how to download NECO Chemistry Practical Questions and Answers. NECO Mathematics Questions are essential for you to know if you want to pass the NECO SSCE Mathematics Exams 2023.

The NECO Chemistry Practical questions and answers is a compiled material in PDF that contains past questions from NECO Mathematics Exams of previous years. The material comes with answers and is easily downloadable. You can download the materials here. The instructions on how to download the NECO Mathematics can be found below. You are expected to follow the instructions in order for you to succeed. The material does not only contain information on NECO Mathematics Questions and answers but how to pass exams as well. You can see this article on the 21 indispensable steps to pass any exams with high grade.

## NECO Chemistry Practical Sample Questions and Answers 2023

(1a)

Tabulate

Volume of pipette used=25cm3.

Indicator used= Methyl orange

Under Titration, Rough, 1st, 2nd, 3rd,

Final burette reading; |25.00| |23.40| |23.50| 23.60|

Initial burette reading; |0.00| |0.00| |0.00| |0.00|

Volume of A used; |25.00| |23.40| |23.50| |23.60|

(1ai)

Average volume of Acid used=23.40+23.50+23.60/3 =70.5/3=23.50cm3

(1aii)

This is because it is a reaction between a weak acid and strong base

(1aiii)

A funnel should be used while transferring the acid into the burette.

(1bi)

Conc of A in mol|dm³ =?

Conc of A in g|dm³ = 12.75g|dm³

Molar mass of A, NaHSO⁴ = 23+1+32+64

=120g|dm³

From.

Conc(mol/dm³) = conc(g/dm³)/molar mass

Conc =12.75/120

Conc =0.106mol/dm³

(1bii)

Con of B in mol/dm³ =?

Ca =0.106, Cb =? Va =23.50cm³, Vb =25.00cm³

na=1 , nb=1

From; CaVa/CbVb=na/nb

Cb=CaVanb/Vbna

Cb=0.10623501/25.001

Cb=2.5/25

Cb=0.1mol/dm³

(1biii)

Conc of B in g/dm³=?

Molar mass of B , NaOH=23+16+1=40g/mol

From; conc(g/dm³)=conc(mol/dm³)molar mass

=0.140

=4.0g/dm³

(1biv)

Mass of salt formed =?

Recall mole of NaHSO⁴=?

From; mole =con(mol/dm³)*vol(cm³)/1000

Mole=0.106*23.50/1000

Mole=0.0025mol of NaHSO⁴

By proportion 1mol of NaHSO⁴ produce 1mol of Na²SO⁴ 0.0025mol of NaHSO⁴ will produce X mol of Na²SO⁴ X=0.00251=0.0025mol of NaSO⁴

Molar mass of Na²SO⁴=(232) + 32 + (16*4)

=46+32+64

=142g/mol

Recall; mole =mole/molar mass

Mass =mole * molar mass

Mass =0.0025*142

Mass =0.36g of Na²SO⁴

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

(2a)

[PLEASE PUT IN A TABULAR FORM]

TEST

C + 5cm³ of distilled water

OBSERVATION

It dissolve completely

INTERFERENCE

C is a soluble salt

(2bi)

TEST

Solution + NaOH + Heat

OBSERVATION

Effervescence occurs in which a colourless gas with pungent smell and turns red litmus paper to blue is given off.

INFERENCES

NH³ gas from NH⁴+ is present

(2bii)

TEST

Stirring rod of HCL + gas given off

OBSERVATION

a gas which gives a pop sound is given off

INFERENCES

H² is present

(2ci)

TEST

Solution C + drops of BaCL²

OBSERVATION

a white precipitate is formed

INFERENCES

CO²^-3, SO²^-4, SO²^-3, May be present.

(2cii)

TEST

Solution in C(i) + dil HCL

OBSERVATION

the white precipitate dissolve is dil HCL and effervescence occurs in which a colourless and odourless gas which turns blue litmus red and lime water milky is given off

INTERFERENCE

CO² gas from CO²^3- confirmed

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

(3a)

(i)Ca²+

(ii)Pb²+

(3bi)

concentrated acid can be defined as an acid formed when a large quantity of an acid dissolve in a small or little volume of water.

(3bii)

A strong acid is defined as a type of acid that ionize completely in a solution

(3c)

Activated charcoal is used as an adsorbent material

(3d)

(i)Reddish – Brown

(ii) I – red, II – brown.

————————————————

### NECO Chemistry Specimen 2023

CHEMISTRY PRACTICAL SPECIMEN:

Requirements:
(a) One burette (50cm³)
(b) One pippete (20cm³/25cm³). However, all
candidates in a center must use pipettes of the
same volume.
(c) The usual apparatus and reagents for
qualitative work including:
(i) Dilute sodium hydroxide solution
(ii) Dilute ammonia solution
(iii) Dilute hydrochloric acid
(iv) Barium chloride solution
(v) Distilled water
(vi) Red and Blue litmus paper
(vii) Phenolphtalein
(d) Methyl orange
(e) One boiling tube
(f) Five test tubes
(g) Filtration apparatus
(h) Source of heat
Each candidate should be supplied with the
following: Labelled An, Bn, Cn, where ‘n’ is the
candidate’s serial number.
(a) 150cm³ of chloride acid solution in a bottle
labelled “An”. The acid solution which should
be the same for all candidates will contain
3.4cm³ of the concentrated hydrochloric acid
per dm³ solution.
(b) 150cm³ of sodium hydroxide solution in a
bottle labelled “Bn”. The solution which should
be the same for all candidates will contain
4.0g of sodium hydroxide per dm³ of solution.
(c) One spatulaful of copper (ii)
tetraoxosulphate (vi) salt in a specimen bottle
labelled “Cn”.

The questions below are strictly for practice not the 2023 Chemistry expo.

All your burette readings (initials and final) as well as the size of your pipette must be recorded but no account of experimented procedure is required. All calculations must be done in your booklet.

1. A is O.200 moldm3 of HCI. C is a solution containing 14/3g of Na2CO3. x H2O in 500 cm3 of solution. (a) Put A into the burette and titrate it against 20.0 cm3 or 25.0 cm3 portions of C using methyl orange as indicator. Repeat the titration to obtain Consistent titre values. Tabulate your results and calculate the average volume of A used. The equation for the reaction is: Na2CO3 x H2O + 2HCL(aq) → 2NaCI(aq) + CO2(g) + (x+1) H2O(I).

(b) From your results and the information provided. Calculate the: (i) concentration of C in moldm-3; (ii) concentration of C in gdm-3; (iii) molar mass of Na2CO3, xH2O; (iv) the value of x in Na2CO3 xH2O. [H = 1.0; C=12.0; O = 16.0; Na =23.0]

Credit will be given for strict adherence to the instruction, for observations precisely recorded and for accurate inferences. All tests, observations and influences must be clearly entered in the booklet in ink at the same time they are made.

2. F is a mixture to two inorganic salts. Carry out the following exercise on F. record your observation and identify any gas(s) evolved. State the conclusions you draw from the result of each test. (a) Put all of F in a beaker and add about 10cm3 of distilled water. Stir well and filter. Keep the filtrate and the residue. (b)(i) To about 2cm3 of the filtrate, add NaOH(aq) in drops and then in excess (ii) To another 2cm3 portion of the solution, add a few drops of NHO3(aq)followed by few drops of AgNO3(aq). (d)(i) Put all the residue into a clean test-tube and add NHO3(aq) followed by few solution from 2(d)(i) add NaOH(aq) in drops and then in excess.

3. State what would be observed if the following reactions are carried out in the laboratory: (i) methyl orange is dropped into a solution of lime juice (ii) hydrogen sulphide gas is bubbled through iron (III) chloride solution; (iii) sulphur (IV) oxide gas is bubbled into acidified solution of KMnO4; (iv) ethanoic acid is added to a solution of K2CO3.

1. Indicator                                 =          Methyl Orange

Volume of the base used        =          25.00cm3

Average Titre              =          1st + 2nd + 3rd/3

=          24.80 + 24.70 + 24.90/3

=          24.80cm3

Alternatively 2 concordant titres can be used to calculate average titre.

Equation of the reaction: Na2CO3 XH2O + 2HCI(aq) → 2NacI(aq) + CO2(aq) + (x+1)H2O(I)

CAVA/CBVB     =  nA/nB

CA = Molar concentration of HCI(aq) in moldm3

VA = Volume of acid used in cm3 = 24.80cm3

CB = Molar concentration of Na2Cu3 xH2O in moldm3

nA = 2

nB = 1

(b)(i) concentration of C in moldm-3 = ? From the equation of reaction:

CAVA/CBVB     =  nA/nB

CA = 0.200 moldm3     VA = 24.80cm3

CB = ?                          VB = 25.00cm3

Substitution of known values

0.200 x 24.80/ CB x 25.00 = 2/1

CB = 1×0.200×24.80/2×25.00

C = 0.0992 moldm-3

(ii) Concentration of C in g dm-3 = ?

500cm2 → 14.3 g

1000cm3 →14.3/500 x 10002 g

= 28.6 g dm-3

(iii) Molar mass of Na2CO3 xH2O

Molar conc in moldm-3 = conc in g dm-3 / molar mass

Therefore: Molar mass g mol-1 = conc in g dm-3 / molar conc in moldm-3

= 28.6 g dm-3/0.0992 moldm-3

= 288.3065

Approximately 288 g mol-1

(iv) Value of x in Na2CO3 xH2O?

[H = 1.0, C = 12.0, O = 16.0, Na = 23.0]

Na2CO3 xH2O = 288

2(23) + 12 + 3 (16) + x (2(I) + 16) = 288

46 + 12 + 48 + 18x  = 288

106 + 18x        = 288

18x      = 288

18x      = 182

x       = 182/18

x       = 10.11

approximately 10

3 (a)(i) Solution of lime juice turns to pink or red. (ii) The FeCI3 solution changes colour from brown to green and a yellow deposit. (iii) The purple colour of the KMnO4 solution turns colourless or decolourised. (iv) The solution of K2CO3 reacts with the addition of ethanoic acid to evolve a colourless, odourless gas with bubbling of effervescence.

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## Tips on How to Pass NECO Examination 2023

If you want to Past the NECO Examination this year, you will need to follow the instructions below.

• Practice daily with NECO Past Questions and Answers
• Write out your subjects, the dates and time.
• Engage in general revision few days to the examination and dwell more on the subjects you find difficult.
• Focus on only your first paper a week to the exam. This would make it sweet and you will have energy to read for other papers.
• Don’t read any other subject when it is two days to a particular subject.
• When you have two papers that are separated by only one day, read the second one first before going to the subject you have first.
• Ensure to be in the NECO examination venue at least two hours to the examination so that you would be balanced.
• Try to be up to date in cases of changes in the timetable.
• Have a personal copy of the NECO timetable and syllabus.
• Go through your timetable daily so that you don’t miss any paper.
• Don’t go to the hall when you are not having paper that day.

Disclaimer: Please note these are not the actual questions and answers that you will find in the NECO Examination this year, but they are the likely questions. to get the actual NECO Past Questions and answers, please call 07063986527.