TODAY’S NECO CHEMISTRY EXPO ANSWERS (OBJ &THEORY) 2017 | In this page we have Neco questions and answers for this june/july 2017 chemistry exams/examinations | TODAY’S NECO CHEMISTRY EXPO ANSWERS (OBJ &THEORY) 2017. Therefore we urge you readers to keep calm and read carefully.
As a matter of fact here is the NECO Chemistry Questions and Answers 2017NECO Chemistry Questions and Answers 2017.
No doubt – The National Examinations Council is an examination body in Nigeria that conducts the Senior Secondary Certificate Examination and the General Certificate in Education in June/July and December/January respectively.
First and foremost let’s work on the Section that has more work and marks.
A mixture contains two or more constituents which can easily be seperated by physical methods.
magnesium trioxonitrate(v) = Mg(NO3)2
molar mass of Mg(NO3)2.
=(1*24) + 2 (14*1 + 16*3)
=24 + 2 (14 + 48)
=24 + 28 + 96 = 148g/mol
% of nitrogen = 2*24*100/148
=% of nitrogen = 48*100/148
% of nitrogen = 4800/148
Finally % of nitrogen = 32.43%.
it is collected by upward delivery.
mass of gas = 1.58*22.4 = 35.392
vapour density = 35.392/1
relative molecular mass= V . D * 2
relative molecular mass= 70.784.
i)carbon monoxide and hydrogen.
ii)carbon monoxide,carbon dioxide,hydrogen and nitrogen.
2Cr + 3 (-2*1 + -2*4) = 0
2Cr + 3 (-2 – 8) = 0
=2Cr + 3 (-10) = 0
2Cr – 30 = 0
2Cr/2 = 30/2
Cr = 15.
vulcanization is a chemical process of converting netural rubber or related polymers into more durable materials through the addition of sulphur or other equivalent curatives or accelerators.
iii)litmus 1cii) NH4Cl+Ca(OH)2—–>CaCl2+2NH3+2H2O 1ciii) it is collected by upward delivery 1civ) mass of gas = 1.58*22.4 = 35.392 vapour density = 35.392/1 relative molecular mass= V . D * 2 =35.392*2 relative molecular mass= 70.784 ==================================.
5ai) i)carbon monoxide and hydrogen ii)carbon monoxide,carbon dioxide,hydrogen and nitrogen 5aii) i)colloids is an intermediate between true solution and a suspension ii)condensation is the process by which water vapour in the air is changed to liquid water.
5bi) CaC03+2HCl—–>CaCl2+H2O+CO2 5bii) i)it is used in fire extinguishers ii)it is used in the manufacturing of mineral water iii)carbon.
4c) TABULATE -THERMOPLASTS- i)it melts when heat is applied to it ii)highly recycled -THERMOSETS- i)does not melt when heat is applied ii)cannot be recycled. ================================== 2ai) ionization energy deals with electron loss while electron loss while electron afinity deals with electron gain 2aii) i)they are used to dry gases.
ii)they are used to recover valuable vapours from industrial effluents and refine petroleum.
2bi) TABULATE -RHOMBIC SULPHUR- i)bright yellow in colour ii)it is octohedral in shape -MONOCLINIC SULPHUR- i)amber in colour ii)it is needle like in shape.
2bii) oxygen = 60% sodium = 40% oxygen 60/16 3.75/1.74 = 2 sodium 40/23 1.74/1.74 = 1 the emperical formula is NaO2 2biii) sodium(iv)oxide 2ci) i)x is hydrophobic region ii)y is hydrophilic religion.
2cii) i)for laundry purpose ii)for fuel 2ciii) i)first and foremost the distance of outermost electron from the nucleus ii)above all the size of the positive nuclear charge iii)finally the screening effect of inner electrons.