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Chemistry
UTME / JAMB 2020
Acids, Bases, and Salts
Solution
Proteins in acid solution undergo?
A
Substitution
B
Fermentation
C
Hydrolysis
D
Polymerisation
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Acid hydrolysis refers to a hydrolysis reaction occurring under acidic conditions. Acid hydrolysis of a protein breaks the polymer down into its constituent amino acids.
Source: Myschool Past Questions Archive (Record #56817)
Chemistry
UTME / JAMB 2020
Matter & Separation Techniques
Solution
The general formula for the Alkanals is?
A
R\(_2\)CO
B
RCHO
C
ROH
D
RCOOR
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Alkanals or Aldehydes have the general formula RCHO while Alkanones or Ketones have the general formula RCOR'.
Where R and R' may be alkyl or aryl groups.
Source: Myschool Past Questions Archive (Record #56818)
Chemistry
UTME / JAMB 2020
Electrochemistry and Redox
Solution
When cathode rays are deflected onto the electrode of an electrometer, the instrument becomes?
A
Bipolar
B
Negatively charged
C
Positively charged
D
Neutral
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
When these cathode rays are deflected onto an electrode of an electrometer, the instrument measured a negative charge. The rays tested also were deflected by application of an electric field.
Source: Myschool Past Questions Archive (Record #56819)
Chemistry
UTME / JAMB 2020
Matter & Separation Techniques
Solution
When a solid substance disappears completely as a gas on heating, the substance is said to have undergone?
A
Sublimation
B
Crystallization
C
Distillation
D
Evaporation
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.
Source: Myschool Past Questions Archive (Record #56820)
Chemistry
UTME / JAMB 2020
Atomic Structure and Periodic Table
Solution
An electron can be added to a halogen atom to form a halide ion with?
A
8 valence electrons
B
7 valence electrons
C
2 valence electrons
D
3 valence electrons
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
A halide ion is a halogen atom bearing a negative charge (which is an anion with a charge of -1). The halide anions are fluoride (F−), chloride (Cl−), bromide (Br−), iodide (I−) and astatide (At−).
Source: Myschool Past Questions Archive (Record #56821)
Chemistry
UTME / JAMB 2020
Matter & Separation Techniques
Solution
Aluminum hydroxide is used in the dyeing industry as a?
A
Dye
B
Dispersant
C
Salt
D
Mordant
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Aluminum hydroxide is also used as a mordant in dyeing.
Source: Myschool Past Questions Archive (Record #56822)
Chemistry
UTME / JAMB 2020
Stoichiometry & Mole Concept
Solution
The most important element on the earth's crust is?
A
Nitrogen
B
Hydrogen
C
Oxygen
D
Fluorine
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Oxygen, O2, is by far the most abundant element in earth's crust at 46.6 percent, nearly half of the mass of the crust.
Source: Myschool Past Questions Archive (Record #56823)
Chemistry
UTME / JAMB 2020
Matter & Separation Techniques
Solution
To obtain pure carbon(ii)oxide from its mixture with carbon(iv)oxide, the mixture should be?
A
Passed over heated copper(ii)oxide
B
Bubbled through water
C
Bubbled through conc H\(_2\)SO\(_4\)
D
Bubbled through conc NAOH
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Carbon(ii)oxide is prepared from carbon(iv)oxide by passing the latter through red-hot carbon and the unchanged CO\(_2\) is removed when the mixture of the gases through conc NaOH.
Source: Myschool Past Questions Archive (Record #56824)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
Which or the following substances is a polypeptide?
A
Starch
B
Glycogen
C
Protein
D
Fats
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
- A polypeptide is defined as a polymer of amino acids joined together by peptide bonds.
- Proteins are polymers of amino acids.
Source: Myschool Past Questions Archive (Record #58788)
Chemistry
WAEC / WASSCE 2020
Organic Chemistry
Solution
Which or the following products could be formed during incomplete combustion of a hydrocarbon.
i.Carbon ii. Hydrogen III. Carbon (Il) oxide
A
I only
B
I and II only
C
I and III only
D
II and III only
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Incomplete combustion occurs when the supply of air or oxygen is poor. Water is still produced, but carbon monoxide and carbon are produced instead of carbon dioxide. The carbon is released as soot.
Source: Myschool Past Questions Archive (Record #58794)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Solution
What quantity of electrons is lost when one mole of iron (II) ions is oxidized to iron (III) ?
A
0 mole
B
I mole
C
2 moles
D
3 moles
medium Difficulty
Verified Correct Answer: Option B
Chemical Principles & Mechanism
Fe\(^{2+}\) → Fe\(^{3+}\)
The pale greenFe\(^{2+}\) is oxidized to orange Fe\(^{3+}\) because it loses an electron.
Source: Myschool Past Questions Archive (Record #58796)
Chemistry
WAEC / WASSCE 2020
Stoichiometry & Mole Concept
Solution
What is the mass of silver deposited when 24,125 C of electricity is passed through a solution or silver salt.
[Ag = 108, IF = 96,500 C ]
A
432g
B
108g
C
54g
D
27g
medium Difficulty
Verified Correct Answer: Option D
Chemical Principles & Mechanism
Ag + e → Ag
1 mole of Ag+ = 108
i.e 108 X 1 X 96500
But, 24,125C will produce ( 108 X 24,125 ) / ( 1 X 96500 )
Ag = 27g
Source: Myschool Past Questions Archive (Record #58797)
Chemistry
WAEC / WASSCE 2020
Stoichiometry & Mole Concept
Solution
Equal masses of calcium trioxocarbonate(iv) were added to dilute hydrochloric acid at the temperature specified. Under which of the following conditions would the reaction be slowest?
A
Calcium trioxocarbonate ( iv ) chips a 20°C
B
CalcIum trioxocarbonate (IV) chips at 40°C
C
Calcium trioxocarbonate (IV) powder at 20'C
D
Calcium trioxocarbonate (IV) powder at 40'C
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
- Increasing the surface area of a reactant increases the frequency of collisions and increases the reaction rate.
- Chips have a lower surface area compared to powder, so it accounts for the slowest
Source: Myschool Past Questions Archive (Record #58798)
Chemistry
WAEC / WASSCE 2020
Acids, Bases, and Salts
Solution
Which of the following substances is an example of a fine chemical?
A
Sodium hydroxide
B
Hydrochloric acid
C
Ethylene
D
Ammonia
medium Difficulty
Verified Correct Answer: Option C
Chemical Principles & Mechanism
Fine chemicals are complex, single, pure chemical substances, produced in limited quantities while Heavy chemicals are produced and handled in large lots and are often in a crude state. Some examples of heavy chemicals are ammonia, sulfuric acid, and sodium hydroxide.
Unfortunately, all the substances provided in the options are heavy chemicals.
Source: Myschool Past Questions Archive (Record #58770)
Chemistry
WAEC / WASSCE 2020
Atomic Structure and Periodic Table
Diagram
Solution
The IUPAC name of the compound represented by the structure below is ?
Attached Figure / Diagram
A
2- chloro but-I ,3-diene.
B
But-1,3-chlorodiene.
C
2-chloro but-diene.
D
3 -chloro but -1.3-diene.
medium Difficulty
Verified Correct Answer: Option A
Chemical Principles & Mechanism
Firstly, we identify the parent name. Here, how many Carbon atoms do we have? Four carbon atoms, i.e But...
However, because there are two C=C double bonds on C-1 and C-3, the parent name will be but,1,3- diene.
Secondly, we identify the substituent group present, which is Chlorine present on C-2 i.e 2- Chloro
Finally, join the two names to get the IUPAC Nomenclature of the compound. i.e 2-chloro but-1,3 diene.
Hence, the correct answer is option A.
Source: Myschool Past Questions Archive (Record #58781)