EXAM: Neco Gce 2024
SUBJECT: Chemistry
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Chemistry Obj-
01-10: CCBBADBABB
11-20: CADDADACBB
21-30: ABBBCCAAAA
31-40: DBBDDABCBC
41-50: DBCBACCDDA
Completed
01-10: CCBBADBABB
11-20: CADDADACBB
21-30: ABBBCCAAAA
31-40: DBBDDABCBC
41-50: DBCBACCDDA
Completed
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
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
6ciii)
NECO GCE 2024 updated Timetable
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