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Chemistry
UTME / JAMB 2007
Periodic Table & Periodicity
Solution
The presence of nitrogen in air is to slow down
A
respiration and combustion
B
combustion and corrosion
C
corrosion and respiration
D
respiration and transpiration
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Nitrogen in the air slows down the burning process of materials, essentially acting as a fire suppressant by diluting the oxygen concentration needed for combustion to occur rapidly; making up the majority of air, it prevents flames from spreading too quickly.
Also,nitrogen in the air does slow down corrosion because it is an inert gas, meaning it doesn't readily react with metals, while the primary contributor to corrosion, oxygen, is displaced by the presence of nitrogen in the atmosphere; essentially, by taking up space, nitrogen limits the amount of oxygen that can come into contact with a metal surface, thus slowing down the corrosion process.
Conversely, nitrogen in the air does not slow down respiration because it is not used in respiration, just as the nitrogen in the soil can affect transpiration rates, but the relationship depends on soil moisture and other factors.
Source: Myschool Past Questions Archive (Record #3994)
Chemistry
UTME / JAMB 2007
Water, Solutions & Solubility
Solution
A good drying agent should be
A
deliquescent
B
effervescent
C
hygroscopic
D
efflorescent
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
A good drying agent should be hygroscopic because this property means it readily absorbs moisture from the surrounding environment, making it effective at drying substances; while efflorescence is the opposite, where a substance releases water, making it unsuitable for drying purposes. Examples of hygroscopic drying agents: Silica gel, calcium oxide, concentrated sulphuric acid.
Source: Myschool Past Questions Archive (Record #3997)
Chemistry
UTME / JAMB 2007
Air & Environmental Chemistry
Solution
Smog usually occurs over cities which
A
burn a lot of fossil fuels
B
have very few plants
C
are surrounded by water
D
are overpopulated
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
The correct answer is A. Burn a lot of fossil fuels.
Smog, a type of air pollution, is often associated with urban areas that burn large amounts of fossil fuels, such as coal, oil, and gasoline. These fuels release pollutants like nitrogen oxides, sulphur dioxide, and particulate matter into the atmosphere, which can react with sunlight and other chemicals to form ground-level ozone and smog.
While options B, C, and D may be related to urban areas, they are not the primary cause of smog. Burning fossil fuels is the main culprit!
Source: Myschool Past Questions Archive (Record #4000)
Chemistry
UTME / JAMB 2007
Stoichiometry, Mole Concept & Volumetric Analysis
Solution
What weight of NaCl is needed to make 2.0 dm3 of a 1.5M solution?
[Na = 23, Cl = 35.5]
A
116 g
B
175 g
C
87 g
D
58 g
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Molar mass of Nacl = 23 + 35.5 = 58.5 g/mol
Number of moles of Nacl = conc. in mol/dm3
x vol. in dm3
= 1.5 * 2.0 = 3.0 moles
1 mole of NaCl has a weight of 58.5 * 3
= 175.5g
Source: Myschool Past Questions Archive (Record #4002)
Chemistry
UTME / JAMB 2007
Organic Chemistry I: Hydrocarbons & Crude Oil
Solution
Use the diagram above to answer the question below:
The alternative raw material labelled M is
A
carbon
B
steam
C
oxygen
D
natural gas
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
The alternative raw material labelled M is steam
Source: Official Exam / Past Question Archive
Chemistry
WAEC / WASSCE 2007
Atomic Structure, Orbitals & Nuclear Chemistry
Solution
When sodium atom form the ion Na+,
A
it gains one proton
B
it achieves a noble gas configuration
C
its atomic number increases
D
it gains one electron
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
When the sodium atom forms an ion, Na+ it loses one electron, i.e. it achieves a noble gas electronic configuration. It will lose one of its 11 electrons to have 10 electrons like neon.
\(Na - e^- → Na^+\)
Na → \(Na^+ + e^-\)
Source: Myschool Past Questions Archive (Record #37132)
Chemistry
WAEC / WASSCE 2007
Chemical Bonding & Intermolecular Forces
Which of the following statements about rare gases are correct?
A
Their outermost shells are fully filled
B
They are generally unreactive
C
Their outermost shells are partially filled
D
They have lone pair of
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #37133)
Chemistry
WAEC / WASSCE 2007
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following properties is characteristic of the halogens?
A
Ability to accept electrons readily
B
Ability to donate electrons readily
C
Ability to from basic oxides
D
Formation of coloured compounds
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #37134)
Chemistry
WAEC / WASSCE 2007
Periodic Table & Periodicity
In which of the following atoms is the ionic radius larger than the atomic radius? [11 Na, 12Mg,13AI,17CI]
A
Aluminium
B
Chlorine
C
Magnesium
D
Sodium
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #37135)
Chemistry
WAEC / WASSCE 2007
Metals, Transition Elements & Extraction
A transition metal would be expected to
A
from oxides with different formulae
B
have strong oxidizing ability
C
have low density
D
have an atomic structure with an incomplete outermost shell
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #37136)
Chemistry
WAEC / WASSCE 2007
Periodic Table & Periodicity
Which of the following properties of atoms generally increases down a group in the periodic table?
A
Electron affinity
B
Electronegativity
C
Ionic radius
D
lonization energy
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #37137)
Chemistry
WAEC / WASSCE 2007
Stoichiometry, Mole Concept & Volumetric Analysis
Which of the following statements about sodium is not true?
A
Na+ is smaller in size than Na
B
Na is smaller in size than Na+
C
Na+ has fewer electrons than Na
D
The effective nuclear charge in Na+ is greater than in Na
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #37138)
Chemistry
WAEC / WASSCE 2007
Chemical Bonding & Intermolecular Forces
If the difference between the electronegativities of two elements is large, the type of bond that can be formed between them is
A
covalent
B
dative
C
ionic
D
metallic
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #37139)
Chemistry
WAEC / WASSCE 2007
Chemical Bonding & Intermolecular Forces
Which of the following compounds has hydrogen bonds between its molecules?
A
HF
B
HBr
C
HCI
D
HI.
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #37144)
Chemistry
WAEC / WASSCE 2007
Chemical Bonding & Intermolecular Forces
Which of the following species does not contain a co-ordinate bond?
A
AI2CI6
B
CCI4
C
H3O+
D
NH + 4
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #37145)