Neco 2021 Chemistry Answers

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(i) Base has bitter taste
(ii) Base is soapy to touch
(iii) Base turns red litmus paper blue

(i)Shift conversion
(ii)Removal of carbon (iv) oxide
(iii)Steam reforming

Cracking is the breaking down or decomposition of a compound by action of heat. It also involves splitting larger molecules into smaller molecules by subjecting them to high temperature and pressures.

Thermal cracking

P ion = 1s²2s²2p⁶

Formula of chloride is Pcl2

Reducing agent
This is because it undergoes oxidation by losing electrons

Electron affinity is the energy released when a gaseous atom gains an electron to form a gaseous negative ion.

This is because it has lone pairs of electrons

(i) By adding a catalyst

(ii) FeS(s) + 2HCl(g) —–> FeCl(g) + H2S(s)

Xg = ?
No. of FeCl2 = 127g/mole
No. of FeS= 88g/mole

Mole = Mass/ No. of Mass = 3.2/127 = 0.025mole of FeCl2

By comparison,
1 mole of FeS = 1 mole of FeCl2
X moles of FeS = 0.025 of FeCl2
X = 0.025mole of FeS

Mass = Mole * molar mass
Mass = 0.025*88
Mass = 2.2g of FeS
X = 2.2g

(2ai) Three postulates of kinetic theory of gasses
(i) gas molecules move randomly in straight lines
(ii) the collisions of gas molecules are perfectly elastic
(iii) the coercive forces between the gas molecules and negligible

Solubility in water easily liquefies

Copper, iron, aluminum, Magnesium


(i) activation energy is the minimum amount of energy possesses by colliding reactants particles for reaction to occur
(ii) catalyst lowers the activation energy
(iii) finely divided nickel
(iv) Sodium trioxocarbonate (iv) (Na2CO3) and Water (H2O)

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(i) it reacts with alkanols to form esters
(ii) It Liberates Carbon(iv) Oxide to form trioxocarbonate (iv)

(i) I.2KI(aq) + Cl2(g) ––> 2KCl2(g) + I(s)
(ii) Zn(s) + Cl2(g) ––> ZnCl2(s)

Cl2 + 2NaOH ––> NaCl + H2O + Q
Q is sodium Trioxochlorate(v)

Covalent bond

(i) Butane
(ii) Propene
(iii) Ethanol
(iv) Ethyne
(i) this is the heat evolved when one mole of the substance is Burned completely and oxygen under standard conditions
(ii) isomerism is a phenomenon where two or more compounds has the same molecular formula but different structures

(i) acidic = NO2
Neutral = CO
basic = Fe2O3
Amphoteric = Al2O3

(i) nitrous oxide
(ii) carbon (iv) oxide

Fractional distillation of liquid air

2KNO3 —> 2KNO2(s) + O2(g)
(NH4)2 (CO)3 —> 2NH3(g) + CO2(g) + H2O(g)

No of molecules=4/16 × 6.02 × 10²³
=1.51 × 10²³

I W = Carbon(iv) Oxide
II Carbon
(iii) I Hydration
III Oxidation

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Updated: July 28, 2021 — 11:05 am

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