2020 free Neco chemistry practical answers
2020 free Neco chemistry practical answers

====Completed====


Our English answers will be posted tonight. Earlier subscribers enjoy earlier answers.

If your English answers not posted tonight, and verified please feel free to request for refund.

Always use our official contact you see on the homepage because those people claiming to be us or partner with, we must fail them this time around. 

Remember, if you didn't get what you paid for, latest 6am, ask for your money back (only those that subscribe before 12midnight through our official contact)



English Language is only

N600 mtn recharge for pin,

N800 for whatsapp,

N1000 for direct as sms,


Send the card to our office number on the homepage either SMS or whatsapp. 

 

Wait for us tonight......

(1a)

Titrationsrough1st2nd3rd
Final Burret reading (cm³)18.0015.6017.4020.50
Initial burret reading (cm³)0.000.002.005.00
Volume of acid used (cm³)18.0015.6015.4015.50

Or

Tabulate:

Titrations |Rough|1st |2nd |3rd |
Final burette reading |18.00|15.60|17.40|20.50|
Initial burette reading |0.00 |0.00 |2.00 |5.00 |
volume of Acide used |18.00|15.60|15.40|15.50|

(1ai)
Average volume of Acid used
VA = (VA1 + VA2 + VA3)cm³/3
VA = (15.60+15.40+15.50)/3
VA = 46.50/3 
VA = 15.50cm³

(1aii)
2HCl(aq)+Na2CO3(aq)-->2NaCl(aq)+H2O(l)+CO2(g)

(1bi)
CA VA/CB VB =NA/NB
0.1moldm-³ x 15.50cm3/CB x 25cm3 x 2/1
CB x 25cm3 x 2 = 0.1moldm-³ x 15.50cm3 x 1
CB x 50 = 1.55
CB = 1.55/50 = 0.031moldm-³

(1bii)
25cm³---->0.031mole
1000cm³---->x
x=1000*0.031/25=31/25
x=1.24moldm-³

(1biii)
concentration in mold-³ =Con glm^³ /molar mass
0.031moldm-³=x/106
x=0.031*106
x=3.29gldm³






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



(2a)
Tabulate

(2ai)
OBSERVATION: C dissolves in water
INFERENCE: C is a soluble salt

(2aii)
OBSERVATION: White precipitate formed
INFERENCE: CO3²-, SO3²-, SO4²- suspected

(2aiii)
OBSERVATION: White ppt dissolves in excess of dil HCl
INFERENCE: CO3²- , SO3²- suspected

(2bi)
OBERSVATION: Effervescence occurs with the evolution of a gas
INFERENCE: CO3²- present

(2bii)
OBERSVATION: Solutions turns to pink
INFERENCE: CO3²- Confirmed



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



(3ai) 
Zinc Chloride(ZnCl2) solution reacts with NaOH(aq) to form white ppt in drops. The precipitate dissolves in excess of NaOH. 

Sodium hydroxide reacts with ammoniumtrioxocarbonate(iv) to form a solution which turns red litmus paper blue. 

Calcium trioxonitrate(v) Ca(NO3)2 on reaction with sodium hydroxide forms a white powder precipitate insoluble in excess NaOH(aq)

(3aii) 
I. Liquid substances - Boiling point of the substances. 
II. Solid substances - The melting point of the substance. 

(3bi) 
(i) Evaporation takes place at almost all temperatures, while Boiling takes place at a specific temperature. 
(ii) Only the surface of a liquid is involved in evaporation while the entire mass of the liquid is involved in boiling. 

(3bii) 
Carbon(iv)oxide does not support combustion. 

(3ci)
A molar solution is an aqueous solution that contains one mole of solute in 1000cm³ of the solution. 

(3cii)
Indicator. 

(3ciii) 
(i) Methyl orange
(ii) Phenolphthalein