Neco chemistry answers 2022

Here is the Neco chemistry answers 2022

NECO CHEMISTRY SOLUTIONS

Chemistry+Obj!

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11BCBCACADCA

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31CCACCACCDE

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51CBACCDCBCD

Theory answers

(1ai)

(i) KAl(SO₄)₂. 12H₂O

(ii) Na₂SO₄

(1aii)

Number of moles of sodium reascted = reacting mass/molar mass

= 3.6/23

= 0.1565moles

Number of moles of oxygen reacted = (1/4) x Number of sodium

= 1/4 x (3.6/23)

= 0.03913

Reacting mass of oxygen = Number of moles x molar mass

= 0.03913 x (16×2)

= 1.252grams

(1bi)

Air in gaseous form is first passed through caustic soda to remove CO₂. It is compressed and cooled until ut becomes a liquid at -200°C. It is then led to a fractionating column. On distillation, Nitrogen which has a lowet boiling point of -196°C is evolced first leaving behind Oxygen in liquid form. Further heating converts the liquid to a gas at -183°C.

(1bii)

(i) It is used for combustion

(ii) It is used for artificial respiration

(1biii)

This is because room temperature is warmer

(1biv)

(i) Methyl orange

(ii) Phenophthalein

(1ci)

An ion is an atom or molecule which has a net electric charge due to the loss or gain of one or more electrons.

(1cii)

HCl gas doesn’t contain ions

(1cii)

(i) Noble gases: Neon, Helium

(ii) Halogens: Iodine, Fluorine

(iii) Alkaline earth metals: Calcium, Magnesium

(1civ)

Halogens attain stable octet configuration by accepting an electron from donors Group I elements.

(1di)

A sol is a colloid where solid particles are dispersed in liquid medium.

(1dii)

Jelly

(1diii)

(i) Acid-base titrations are used to determine the percentage purity of a substance

(ii) Acid-base titrations are important to determine the number of water molecules in a hydrate.

1a
i. ammonium iron(II) sulfate

ii. NaCl

aii) Loading…

bi)

The liquid air undergoes a process called fractional distillation. Fractional distillation uses the different boiling points of the main elements of air. As the liquid air is heated, the elements change from liquid to gas and separate from one another. Pump air through a filter to remove dust and other contaminants.

ii)

1. production of steel, plastics and textiles

2. rocket propellant

iii)

If the room is closed, all vapor generated by boiling will stay in the room, If it is at constant volume, the pressure will rise in it.

iv)

1. Phenol Red

2. Methyl Orange

ci)

An ion is an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons.

ii)

HCI gas does not conduct electricity, but hydrochloric acid conducts electricity because in hydrochloric acid( aq), hydrogen ions are present to facilitate the movement of electrons whereas no such medium is present in gas

iii)

I. Noble Gases: Helium,Neon

II. Halogens: Flourine,Iodine

III. Alkaline earth metals: Magnesium,Calcium

iv)

They form bonds like those in the chlorine molecule: one single bond between atoms and three lone pairs of electrons per atom.

di)

Sol is a colloid (aggregate of very fine particles dispersed in a continuous medium) in which the particles are solid and the dispersion medium is fluid.

ii)

Gel

iii)

1. To determine the acid solution concentration by titrating it with a basic solution of known concentration, or vice versa until there is neutralization.

2. To analyse the purity of medicines.

(2ai)
A molar solution of a compound contains one mole or the molar mass of the compound in one dm³ of the solution.

(2aii)
(i) Identification of gases
(ii) Identification of acidic and metallic radicals

(2aiii)
(i) Purification of bauxite
(ii) Electrolysis of alumina

(2bi)
[img]https://i.ibb.co/vPBwDjB/IMG-20220725-WA0082.jpg[/img]

(2bii)
This is because of the presence of copper which is a transition metal

(2bii)
(i) Methanamide is a liquid while the rest amides are crystalline solids
(ii) Melting points and boiling points of aides are much higher than expected.

(2ci)
(i) Heavy chemicals are produced in very large quantities in industries While fine chemicals are produced in small quantities for specific purposes
(ii) Heavy chemicals are in a crude state While fine chemicals are purified.

(2cii)
(i) Million’s reagent
(ii) Feeling’s solution

(2ciii)
Graham’s law of diffusion states that at a constant temperature and pressure the rate of diffusion of a gas is inversely proportional to the square root of its density.

(2civ)
RO₂/RCH₄ = √(MCH₄/MO₂)
5/(200/t) = √[(12+4)/(16×2)]
5t/200 = √16/32
t/40 = 1/√2
t = 40/√2
t = (40/√2) × (√2/√2)
t = 20√2 seconds
Time taken = 28.28 seconds.
CHEMISTRY OBJ
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11-20: BCDCAAEDCC
21-30: ABCBDDAACC
31-40: CCACBACCDE
41-50: DDDEDDBDAD
51-60: CBACCEDBBD

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