NECO GCE Chemistry practical Questions And Answers For 2018

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NECO GCE Chemistry practical Questions And Answers For 2018

 

NECO GCE 2018 CHEMISTRY PRACTICAL Expo FROM EXAMCLASS.NET
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1ai)
Tabulate
Titration|1|2|3|
Final burette reading (cm^3) |21.30|
21.50|24.00|
Initial burette reading (cm^3) |01.30|01.00|03.50|
Volumeeading are when the reading are exactly the same

1aiv)
Because it is a reaction between strong acid and strong base

1av)
i)Avoid air bubbles in the pipette
ii)rinse the pipette with the base solution before use

1avi)
the base sodium hydroxide has a soapy feel

1bi)
mole= 0.6mol1dm^3*20.50cm^3/1000
=1.23/1000=0.00123mole

1bii)
conc in mol1dm^3
=4.0/40=0.1mol1dm^3

1biii)
mole =0.1mol1dm^3*25cm^3/1000
=2.5/1000=0.0025mole

1biv)
mole of acid = 0.00123mole m 0.001mole
mole of base= 0.0025mole m 0.003mole
mole ratio =0.001/0.003=1:3

1ci)
it is a strong acid.
Methly orange is used as an indicator in a strong acid, strong base titration

1cii)
H3PO4+3NaOH—>Ha3PO4+3H2O

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(2a)
C is soluble salt

(2ai)
– Zn^2+ or Al^3+ present
– Zn^2+ or Al^3+ present

(2aii)
– Zn^2+ or Al^3+ present
– Zn^2+ is confrim

(2bi)
SO3^2- or SO4^2-present

(2bii)
SO3^2- present

(2biii)
SO3^2- confrim

(2c)
ZnSO3

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(3a)
(i) Co2 can be removed by adding canstic soda i.e sodium hydroxide
(ii) purity of water can be determined through it boiling point as it is noted that pure water boils at 100oc
(iii)
AgN03 produce brown fumes as NO2 is produced on heating as 2AgNO3 (s) ==> 2Ag(s) + O2(g) 2NO2(g)
(iv)
It changes the litmus paper red as the hydrogen ion in the wet litmus forms as acid on exposure to the litmus paper.

(3b)
(i) it don’t like drowing
(ii) it cannot be collected by displacement of air because nitrogen constitutes to large percentage of the air constitutes (78%)
(iii) HCL gas or ammonia gas

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