WAEC GCE 2020 – CHEMISTRY QUESTIONS AND ANSWERS ( Practical)

 

Welcome To NAIJASKUL Exam Page We will Deliver You the WAEC GCE Chemistry Questions and Answers 2020 (Practical) before the examination time. To subscribe to us for the full exam package, please send a text as we serve you better.

 

Monday 3rd Dec. 2020

Paper III: Practical – Chemistry
2:00pm – 3:30pm

DIRECT MOBILE SMS: N800

PASSWORD LINK: N400

DELIVERY TIME: A DAY/MIDNIGHT

Send the following;
(i)MTN CARD PIN
(ii)Amount Paid
(iii) Subjects
(iv) Phone number
TO 07066454548

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

Pay To Get Pure A1 In Your CHEMISTRY

TELL YOUR FRIENDS CHEMISTRY PAYMENT IS ON PAY AND GET ADDED IN TIME FOR NIGHT ANSWERS

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

 

SUBSCRIBE WITH US TO RECEIVE YOUR ANSWERS BEFORE OTHERS

 

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

2020-WAEC-GCE-Chemistry-Practicals-ANSWERS

(1a)
Mass number A = 1.85g
Vol of A = 250cm³
Mass of B =400g in 1dm³

Average title = 25.00+24.90/2

=49.90/2=24.95cm³

Edited.
(1b)
(i) pink
(ii) colourless

(1ci)
Conc of B in mol/dm³ ; ?
Mole =4.00/40 =0.1mol

Mole = conc * vol(dm³)
Conc =mole/vol
Conc =0.1/1
Conc=0.1mol/dm³
Conc of B =0.1mol/dm³

(1cii)
Cb=0.1mol/dm³ , Vb=25.0cm³ , Ca =? Va=24.95cm³
na=1, nb=1
CaVa/CbVb
Ca*24.95/0.1*25.0=1/1
Ca=0.1*25.0/24.95=2.5/24.95=0.100mol/dm³

(1di)
Molecular mass=?
Mass conc =1.85/250*1000
=7.4g/dm³
Conc(mol/dm³)=mass conc/molar mass
0.1=7.4/molar mass
Molar mass =7.4/0.1= 75g/mol

(1dii)
A=CnH²n+1COOH
CnH²n+1COOH=74
(12*n)+(1x(2n+1)+12+16+16+1=74
12n+2n+1+45=74
14n+46=74
14n=74-46
14/14=28/14
n=2
C²H⁵COOH

(1e)
This is because it is a reaction between weak acid and strong base

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

(2a)
TEST
C(aq) + HCl

OBSERVATION
No gas evolved/No observable reaction

INFERENCE
SO²,⁴^- Some may be Present

(2b)
TEST
C+BaCl² + dili H²SO⁴

OBSERVATION
White Precipitate Formed Precipitate insoluble remain Undissolved

INFERENCE
SO²,⁴^- confirmed

(2ci)
TEST
C+NaOH(aq) In drop them in excess

OBSERVATION
No precipitate / No visibie reaction
No Observation reaction.

INFERENCE
Probably NH+⁴ Present

(2cii)
TEST
mixture in c(i) warmed

OBSERVATION
Gas is evolved
Gas is basic
Gas has a Pungent or smell

INFERENCE
NH₃ gas evowed hence NH³ presert

(2di)
TEST
C+HNO³ + AgNO³

OBSERVATION
No observable reaction
No gas evolved

INFERENCE
C1^- Present

(2dii)
TEST
Precipitate + HNO³

OBSERVATION
White precipitate
Precipitate insolubie

INFERENCE
C1^-confirmed

(2ei)
(i)(NH⁴)²SO⁴
(ii)NH⁴Cl

(2eii)
(i)Ammonium teraoxosulphate(iv) salt(NH⁴)²SO⁴)
(ii)NH⁴CI > Ammonium chloride

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

(3ai)
There will be evolution of SO²

(3aii)
a green color is observed

(3aiii)
There is effervescence I:e CO² is liberated

(3b)
(i)HCl
(ii)Zn(OH) will dissolves readily while (⁴(OH)² will not.

(3c)
(i)it reduce the mass of the salt
(ii)to purity it

 

 

%d bloggers like this: