2020 Waec Chemistry Practical Correct Questions and Answers Expo        

logo






FOR ENQUIRY:: ONLY TEXT OR WHATSAPP US WITH OUR ADMIN NUMBER 07058713598 (CALLS ARE NOT ALLOWED, DUE TO WE ARE VERY BUSY)


 

« | »

2020 WAEC CHEMISTRY PRACTICAL CORRECT QUESTIONS/ANSWERS VERIFIED EXPO

Waec 2020 runs for gistpower.com

WAEC-CHEMISTRY-PRACTICAL-ANSWERS

(1a)
Burette reading (cm)³|1st reading|2na Reading|3rd reading|
Final |15.25|30.53|45.79|
Initial |0.00|15.25|30.53|
Volume of acids used |15.25|15.28|15.26

Average volume of acid used =15.25+15.26/2
=15.255cm³
=15.26cm³
Or =15.27cm³

(1b)
Given; mass con of A =5g/500cm³ = 5g/0.5dn³
CA=10g/dm³
A is HNO3
Therefore molar mass =1+14+(16*3)=15+48=63g/mol¹

Molarity of A = gram con/molar mass
CA=10/63=0.1587mol/dm3

(1bii)
Using CAVA/CBVB =Na/NB
With reacting equation ; HNO³ + NaOH—NaNO3+H2O
nA=1 nB=1
0.1587*15.26/CB*25.00=1/1
25CB=0.1587*15.26
CB=0.1587*15.26/25
CB=0.09687mol/dm³

(1biii)
B is NaOH
Molar mass
23+16+1=40g/mol
Conc of B in g/dm³=molarity * molar mass
= 0.09687*40
=3.8748g/dm³

(1biv)
No of moles present in 250cm³ of NaOH is =molar conc * volume
=0.09687*250/1000
=0.0242moles
Mole ratio of NaOH and NaNO3 is 1;1
No; of mole of NaNO3 which reacted is 0.0242
Mass of NaNO3 formed =molar mass * no; of moles
=85*0.0242
=2.05grams

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

(2a)
TEST: C+burning splint

OBSERVATION: Sample C burst into flame .It burns with non smoky blue flame without soot. Colorless gas that turns wet blue litmus paper faint red and turns like water milky is present.

CHECK OUT:  WAEC 2019 FINANCIAL ACCOUNTING OBJ AND ESSAY VERIFIED ANSWER

INFERENCE: C is volatile and flammable. The gas is CO2 from combustion of saturated organic compound.

(2bi)
TEST: C + distilled water + shake

OBSERVATION: Clear or colorless solution is observed

INFERENCE: C is miscible with water

(2bii)
TEST: C + Acidified K2Cr207

OBSERVATION: Orange color of K2Cr207 solution turns pale green and eventually pale blue on cooling

INFERENCE: C is a reducing agent

(2C)
TEST: D + C + 10% NaOH + Shake

OBSERVATION: D dissolves slowly in C and produces reddish brown solution. Reddish brown solution turns yellow precipitate. The precipitate has an antiseptic odour
INFERENCE: D is soluble in organic solvents

(2d)
Compound belongs to the class of secondary alkanol

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

(3ai)
Zinc nitrate

(3aii)
2 Zn(NO 3 )2 —–>2 ZnO + 4 NO 2 + O 2

(3aiii)
It turns white when cold from it yellow colour when it was hot

(3b)
Pipette / measure 50.0cm3 of the stock solution into a 250
cm3 volumetric flask (containing some distilled water). Shake / swirl and add more distilled water until the mark is reached.

(3c)
Al2(SO4)3 – turns blue litmus red
=====================================
Complete.

CHECK OUT:  2020 WAEC AGRICULTURAL SCIENCE OBJ AND ESSAY CORRECT QUESTIONS/ANSWERS VERIFIED EXPO

(1)

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

Solving….

KEEP REFRESHING Every Minutes..

Tags: ,

Categories: Waec runs 2020 expo answer supply


SELECT EXAM YOU WILL WRITE AND CLICK ON IT

2 Responses

  1. Ceebook direct me to you that u are the best

    by john on Jun 13, 2020 at 11:41 pm

  2. I need answers and question for all subject

    by Anonymous on Aug 19, 2020 at 1:27 pm

Leave a Reply

« | »


For Daily/Per Subject Subscribers, Always Send Your Subscription a Day or Two Days Before Your Paper!



Open Chat
1
Whatsapp Us
ADMIN
Dear Candidate, Welcome to Gistpower.
Subscription for our NECO / WAEC GCE 2020 RUNS is in
progress!
SCORING A's & B's is 100% sure if you
subscribe with us.
Click the Open chat let's hear from you!