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NECO GCE LITERATURE IN ENGLISH #1000✅

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Waec Gce chemistry practical 👇

2a)
In a Tabular form

=TEST=
A + heat

= OBSERVATION=
Colourless, odourless gas turned limewater milky.

=INFERENCE=
CO₂ gas evolved, indicating a carbonate or bicarbonate.

(2b)
=TEST=
Residue from (a) + water + litmus paper

=OBSERVATION=
Dissolved to form a colourless solution, turned red litmus paper blue.

=INFERENCE=
Basic solution, likely an alkali such as a metal hydroxide (e.g, Ca(OH)₂).

(2c)
=TEST=
Solution from (b) + NaOH(aq) in drops, then in excess

=OBSERVATION=
White precipitate formed, soluble in excess NaOH.

=INFERENCE=
Al³⁺ ions present.

(2d)
=TEST=
B + water

=OBSERVATION=
Soluble salt.

=INFERENCE=
No direct reaction or insoluble residue indicates a soluble ionic compound.

(2e)
=TEST=
Solution from (d) + NaOH(aq) in drops, then in excess

=OBSERVATION=
White gelatinous precipitate formed; precipitate soluble in excess.

=INFERENCE=
Al³⁺ ions confirmed.

(2f)
=TEST=
Solution from (d) + NH₃(aq) in drops, then in excess

=OBSERVATION=
White precipitate formed, insoluble in excess.

=INFERENCE=
Al³⁺ ions confirmed.

(2g)
=TEST=
Solution from (d) + AgNO₃(aq) + HNO₃(aq) + NH₃(aq) in excess

=OBSERVATION=
White precipitate formed with AgNO₃, soluble in NH₃ after adding HNO₃.

=INFERENCE=
Cl⁻ ions present and confirmed.

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Waec Gce Chemistry Pract-
(3a)
(i) Distillation (for liquids with different boiling points).
(ii) Fractional distillation (for miscible liquids with closer boiling points).

(3bi)
Tongs
(PICK ANY ONE)
(i) Holding hot test tubes, beakers, or crucibles during heating.
(ii) Picking up small pieces of substances or glassware.
(iii) Removing a hot lid from a container.
(iv) Gripping and placing objects into a furnace or flame.

(3bii)
Wire gauze
(PICK ANY ONE)
(i) Supporting glassware (like a beaker) over a flame.
(ii) Distributing heat evenly under a heated container.
(iii) Preventing direct contact between glass and flame to reduce breakage.
(iv) Acting as a platform for conducting flame tests.

(3biii)
Beehive shelf
(PICK ANY ONE)
(i) Supporting a gas jar during gas collection over water.
(ii) Keeping the gas jar stable while transferring gases.
(iii) Directing gas from the delivery tube into the gas jar.
(iv) Serving as an intermediary platform to avoid gas loss during collection.

(2biv)
Spatula
(PICK ANY ONE)
(i) Transferring small amounts of solid chemicals from containers.
(ii) Mixing solid substances or scooping powders for weighing.
(iii) Scraping residues from containers.
(iv) Adding controlled amounts of a solid to a reaction mixture.

(3c)
In a Tabular form

=GAS=
(i) H₂
(ii) CO₂
(iii) C₂H₂

=SOLID=
(i) Mg
(ii) CaCO₃
(iii) CaC₃

=LIQUID=
(i) Dil. HCL
(ii) Dil. HCL
(iii) Cold water

(3d)
Add dilute hydrochloric acid (HCl) to both solutions

(i) NaOH(aq): No visible reaction occurs, as it only forms water and salt.

(ii) Na₂CO₃(aq): Effervescence (bubbling) occurs due to the release of carbon dioxide gas (CO₂), which can be confirmed by bubbling it through limewater that turns milky.

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WAEC GCE CHEMISTRY PRACTICAL ☝️☝️☝️

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NECO CHEMISTRY
01-10: ECCECDAAAE
11-20: CAEDBDACCB
21-30: EDACACDDCC
31-40: DEEBAECECC
41-50: BACBBBBCDA
51-60: ABCDADDBEB
COMPLETED

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6ai)
I - Sulphur dioxide (SO₂) and sulphur trioxide (SO₃)
II - Carbon monoxide (CO), unburnt hydrocarbons, and particulate matter (soot)

(6aii)
Efflorescence is the phenomenon where a hydrated salt loses its water of crystallization when exposed to air, forming a powdery surface.

(6aiii)
Fe + 2HCL → FeCL₂ + H₂

(6aiv)
(PICK ANY THREE)
(i) Applying a protective coating (e.g., paint or grease).
(ii) Galvanization (coating with zinc).
(iii) Using stainless steel or alloys.
(iv) Electroplating (coating the metal surface with another metal, such as chromium or nickel).
(v) Using sacrificial anodes (attaching a more reactive metal like zinc to corrode instead of the iron).
(vi) Storing metals in a dry or controlled environment to prevent exposure to moisture and oxygen.

(6bi)
Number of moles in 5.0×10²⁰ atoms of magnesium

Moles = Number of atoms / Avogadro's number
Moles = 5.10 × 10²⁰ / 6.02 × 10²³
Moles = 8.31 × 10-⁴

(6bii)
Petroleum gasses→ Petrol → Ligroin → Kerosene

(6biii)
Octane rating measures the fuel's ability to resist knocking during combustion in an engine. Higher ratings indicate better performance.

(6biv)
Variation of electron affinity across a period, electron affinity generally increases across a period due to an increase in nuclear charge, which attracts electrons more strongly.

(6ci)
Na₂CO₃ - 7H₂O
Molar mass of Na₂CO₃ - 7H₂O =
(23×2) + 12 + (16 × 3) + 7 [(2×1) + 16] =
286g/mol

Mass of oxygen
(3×16) + (7×16) = 112 + 16
= 128g

(6cii)
Draw the diagram below

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6ciii)
Ammonia gas turns moist red litmus paper blue due to its basic nature.

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