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Chemistry
UTME / JAMB 2022
Matter & Separation Techniques
Solution
Hard water is water with high concentrations of dissolved ions, in particular calcium and
A
magnesium ions
B
nitrogen ions
C
phosporus ions
D
helium ions
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Hard water is water with high concentrations of dissolved ions, in particular calcium and magnesium ions
Source: Myschool Past Questions Archive (Record #66999)
Chemistry
UTME / JAMB 2022
Matter & Separation Techniques
Solution
Hard water is water with high concentrations of dissolved ions, in particular calcium and
A
magnesium ions
B
nitrogen ions
C
phosporus ions
D
helium ions
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Hard water is water with high concentrations of dissolved ions, in particular calcium and magnesium ions
Source: Official Exam / Past Question Archive
Chemistry
WAEC / WASSCE 2022
Matter & Separation Techniques
Solution
Which of the following sketches is a graphical representation of Boyle's law?
A
A
B
B
C
C
D
D
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Boyles law states that the volume of a given mass of gas is inversely proportional to pressure at constant temperature.
Source: Official Exam / Past Question Archive
Chemistry
UTME / JAMB 2021
Matter & Separation Techniques
Solution
Which one of the following is not a mixture?
A
Air
B
Mercury
C
Milk
D
Cement
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
A mixture is a material made up of two or more different chemical substances which are not chemically combined.
Mercury is a chemical element with the symbol Hg and atomic number 80.
Source: WAEC / JAMB / NECO Classroom Archive (Record #60424)
Chemistry
UTME / JAMB 2021
Matter & Separation Techniques
Solution
Oxygen is absent in?
A
Kerosene
B
Soil
C
Glass
D
Cement
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Kerosene contains hydrocarbon with twelve to eighteen carbon atoms per molecule
Source: WAEC / JAMB / NECO Classroom Archive (Record #60466)
Chemistry
UTME / JAMB 2021
Matter & Separation Techniques
Solution
A sample of any of the following substances disappears after some time when exposed to air like camphor, naphthalene, or dry ice. This phenomenon is called?
A
Sublimation
B
Evaporation
C
Diffusion
D
Radiation
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state.
Familiar substances that sublime readily include iodine, dry ice, menthol, and camphor.
Source: WAEC / JAMB / NECO Classroom Archive (Record #60468)
Chemistry
UTME / JAMB 2021
Basic Chemistry
Solution
The atomic weight of nitrogen is?
A
10
B
12
C
14
D
16
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Atomic weight, also called relative atomic mass, ratio of the average mass of a chemical element's atoms to some standard.
Source: WAEC / JAMB / NECO Classroom Archive (Record #60463)
Chemistry
UTME / JAMB 2021
Basic Chemistry
Solution
The maximum electron in N shell is?
A
2
B
8
C
18
D
32
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
The N shell is the fourth orbit with 32 max number of electrons using 2n\(^2\)
Source: WAEC / JAMB / NECO Classroom Archive (Record #60469)
Chemistry
UTME / JAMB 2021
Basic Chemistry
Solution
The mass number of a nucleus is?
A
Always less than its atomic number
B
The sum of the number of protons and neutrons present in the nucleus
C
Always more than the atomic weight
D
A fraction
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
mass number, is the sum of the numbers of protons and neutrons present in the nucleus of an atom.
Source: WAEC / JAMB / NECO Classroom Archive (Record #60498)
Chemistry
UTME / JAMB 2021
Basic Chemistry
Solution
The mass of one Avogadro number of helium atoms is?
A
1.00gram
B
4.00gram
C
8.00gram
D
6.00gram
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Avogadro's number is an absolute number: there are 6.022\times10\(^23\) elementary entities in 1 mole.
helium has a molar mass of 4.0 grams per mole. So one mole of helium has a mass of 4.0 grams.
Source: WAEC / JAMB / NECO Classroom Archive (Record #60499)
Chemistry
UTME / JAMB 2021
Basic Chemistry
Solution
220g of carbon dioxide contains ----- moles
A
5
B
6
C
3
D
4
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
One mole of carbon dioxide molecules has a mass of 44.01 g,
: 5 mole of carbon dioxide molecules has a mass of 220g
Source: WAEC / JAMB / NECO Classroom Archive (Record #60501)
Chemistry
UTME / JAMB 2021
Basic Chemistry
Solution
The nucleus of an atom consists of?
A
Electrons and neutrons
B
Electrons and protons
C
Protons and neutrons
D
None of the above
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
An atom nucleus is made up of protons and neutrons.
An electron is a negatively charged subatomic particle that orbits the nucleus of an atom.
Source: WAEC / JAMB / NECO Classroom Archive (Record #60510)
Chemistry
UTME / JAMB 2021
Basic Chemistry
Solution
The process by which salt and water reacted in a limited way to form an acid or a base is?
A
Neutral process
B
Basic acidic process
C
Hydrolysis
D
Sublimation
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
- Hydrolysis is any chemical reaction in which a molecule of water breaks one or more chemical bonds.
-Salt hydrolysis is a reaction in which one of the ions from a salt reacts with water, forming either an acidic or basic solution.
Source: WAEC / JAMB / NECO Classroom Archive (Record #60537)
Chemistry
WAEC / WASSCE 2021
Basic Chemistry
Solution
The Bohr model of the atom proposed the existence of?
A
the nucleus
B
electron shells
C
nucleons
D
neutrons
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Bohr Model is a planetary model in which the negatively charged electrons orbit a small, positively charged nucleus similar to the planets .
Source: WAEC / JAMB / NECO Classroom Archive (Record #62092)
Chemistry
WAEC / WASSCE 2021
Acids, Bases, and Salts
Solution
The basic property of salts used as drying agents is by?
A
efforescence
B
high melting point
C
hygroscopy
D
low solubility
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Hygroscopic substances are used to keep products dry or to remove water from an area. They are commonly used in desiccators
Some common examples of hygroscopic substances include: Sodium chloride. Zinc chloride. Calcium chloride
Source: WAEC / JAMB / NECO Classroom Archive (Record #61979)