Chemistry Quiz Questions: MCQ Exam!
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Questions and Answers
- 1.
Which of the following relations is correct?
- A.
Cp x Cv = R
- B.
Cp – Cv = R
- C.
Cv – Cp = R
- D.
Cp + Cv = R
Correct Answer
B. Cp – Cv = RExplanation
The correct relation is Cp - Cv = R. This equation represents the difference between the specific heat at constant pressure (Cp) and the specific heat at constant volume (Cv) being equal to the gas constant (R). This equation is derived from the first law of thermodynamics and is used to relate the thermodynamic properties of a gas.Rate this question:
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- 2.
Value of ∆H for exothermic reaction is
- A.
+ve
- B.
–ve
- C.
+ve or – ve
- D.
Zero
Correct Answer
B. –veExplanation
An exothermic reaction is a reaction that releases heat to its surroundings. The negative sign in front of the answer indicates that the enthalpy change (∆H) for an exothermic reaction is negative. This means that the products of the reaction have a lower energy than the reactants, and energy is released during the reaction.Rate this question:
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- 3.
The efficiency of heat engine is always:
- A.
Less than one
- B.
More than one
- C.
Zero
- D.
None of these
Correct Answer
A. Less than oneExplanation
The efficiency of a heat engine is always less than one because it represents the ratio of useful work output to the total energy input. In any heat engine, some energy is always lost as waste heat, resulting in a decrease in the efficiency. Therefore, the efficiency value will always be less than one, indicating that not all of the input energy is converted into useful work.Rate this question:
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- 4.
The entropy of the universe is:
- A.
Increases
- B.
Decreases
- C.
Does not change
- D.
None of these
Correct Answer
A. IncreasesExplanation
Entropy is a measure of the disorder or randomness in a system. According to the second law of thermodynamics, the entropy of an isolated system tends to increase over time. This means that the universe as a whole is constantly moving towards a state of higher disorder. Therefore, the correct answer is "Increases".Rate this question:
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- 5.
The cell constant is expressed by:
- A.
A/l
- B.
L/a
- C.
L + a
- D.
L x a
Correct Answer
B. L/aExplanation
The cell constant is expressed by l/a because the cell constant is defined as the ratio of the distance between the electrodes (l) to the cross-sectional area of the electrodes (a). Therefore, the correct expression would be l/a.Rate this question:
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- 6.
The standard electrode potential of the hydrogen electrode.
- A.
Positive
- B.
Negative
- C.
Zero
- D.
Both positive and negative
Correct Answer
C. ZeroExplanation
The standard electrode potential of the hydrogen electrode is zero because it is used as a reference electrode to measure the electrode potentials of other half-cells. The hydrogen electrode consists of a platinum electrode in contact with a solution of hydrogen ions at a pressure of 1 atm. The electrode potential is measured relative to the standard hydrogen electrode, which is assigned a value of zero. This means that the hydrogen electrode does not have a tendency to gain or lose electrons and serves as a baseline for comparing the electrode potentials of other half-cells.Rate this question:
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- 7.
The sum of pH and pOH will be
- A.
0
- B.
10
- C.
7
- D.
14
Correct Answer
D. 14Explanation
The sum of pH and pOH will be 14 because pH and pOH are related to each other through the equation pH + pOH = 14. The pH scale measures the concentration of hydrogen ions in a solution, while the pOH scale measures the concentration of hydroxide ions. Since the sum of the concentrations of hydrogen ions and hydroxide ions in a solution is always constant at 10^-14 M^2, the sum of pH and pOH will always be 14.Rate this question:
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- 8.
In the periodic table total no of periods are:
- A.
6
- B.
8
- C.
9
- D.
7
Correct Answer
D. 7Explanation
The correct answer is 7 because the periodic table is organized into rows called periods, and there are a total of 7 periods in the periodic table. Each period represents a different energy level or shell in which the elements' electrons are arranged.Rate this question:
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- 9.
EDTA is which type of ligand?
- A.
Bidentate
- B.
Tridentate
- C.
Quadridentate
- D.
Hexadentate
Correct Answer
D. HexadentateExplanation
EDTA is a hexadentate ligand because it has six donor atoms that can form coordinate bonds with a central metal ion. The six donor atoms in EDTA are the two nitrogen atoms from the amino groups and the four oxygen atoms from the carboxylate groups. This allows EDTA to form strong and stable complexes with metal ions by coordinating through all six of its donor atoms simultaneously.Rate this question:
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- 10.
Plutonium is the element of _______block.
- A.
S
- B.
P
- C.
D
- D.
F
Correct Answer
D. FExplanation
The element Plutonium belongs to the f-block. This block consists of the inner transition metals, also known as the lanthanides and actinides. Plutonium is an actinide element, specifically belonging to the actinide series. Therefore, the correct answer is f.Rate this question:
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- 11.
Total number of sigma bond involved in ethylene molecule are:
- A.
3
- B.
5
- C.
2
- D.
1
Correct Answer
B. 5Explanation
In an ethylene molecule, there are a total of 5 sigma bonds involved. Each carbon atom forms 3 sigma bonds with the surrounding atoms, and there is a double bond between the two carbon atoms. The double bond consists of one sigma bond and one pi bond. Therefore, the total number of sigma bonds in an ethylene molecule is 5.Rate this question:
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- 12.
Organic compounds are non-conductors of electricity because they:
- A.
Are insoluble in water
- B.
Do not form ions
- C.
Have low melting point
- D.
Form free radicals
Correct Answer
B. Do not form ionsExplanation
Organic compounds are non-conductors of electricity because they do not form ions. Unlike inorganic compounds, which often dissociate into ions in water, organic compounds do not have the ability to form ions due to their molecular structure. This lack of ions prevents the flow of electric current through the compound, making it a non-conductor of electricity.Rate this question:
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- 13.
Heterolytic fission of C-Br bond results in the formation of:
- A.
Free radicals
- B.
Carbanion
- C.
Carbocation
- D.
Carbanion and carbocation
Correct Answer
D. Carbanion and carbocationExplanation
Heterolytic fission of a C-Br bond results in the formation of a carbanion and a carbocation. Heterolytic fission occurs when the bond breaks unevenly, with one atom receiving both electrons from the bond. In this case, the carbon atom gains the electron pair, forming a carbanion, while the bromine atom becomes positively charged, forming a carbocation. This process is a common reaction in organic chemistry, often seen in nucleophilic substitution reactions involving alkyl halides.Rate this question:
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- 14.
Resonance is not exhibited by
- A.
Phenol
- B.
Aniline
- C.
Nitrobenzene
- D.
Cyclohexane
Correct Answer
D. CyclohexaneExplanation
Resonance is a phenomenon where electrons are delocalized and can move between different atoms or bonds. It is typically observed in molecules with conjugated systems, such as phenol, aniline, and nitrobenzene, where there are alternating double and single bonds. However, cyclohexane does not have any conjugated systems or alternating double and single bonds, so it does not exhibit resonance.Rate this question:
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- 15.
Which of the following species does not act as nucleophile?
- A.
ROH
- B.
ROR
- C.
PCl3
- D.
BF3
Correct Answer
D. BF3Explanation
BF3 does not act as a nucleophile because it does not have a lone pair of electrons to donate. Nucleophiles are species that donate electron pairs to form new chemical bonds. In the case of BF3, it is an electron-deficient molecule with an incomplete octet, meaning it lacks the necessary electron pair to act as a nucleophile.Rate this question:
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- 16.
Which of the following alkanes can not be prepared by Wurtz reaction?
- A.
Methane
- B.
Ethane
- C.
Propane
- D.
Butane
Correct Answer
A. MethaneExplanation
The Wurtz reaction is a method used to prepare alkanes by reacting alkyl halides with sodium metal in the presence of an inert solvent. However, methane cannot be prepared by the Wurtz reaction because it does not have a halogen atom to react with sodium metal. Methane is the simplest alkane and consists of only one carbon atom bonded to four hydrogen atoms. Since it lacks a halogen atom, it cannot undergo the Wurtz reaction.Rate this question:
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- 17.
Which of the following compounds is an example of alkynes?
- A.
C3H8
- B.
C3H6
- C.
C3H4
- D.
C4H8
Correct Answer
C. C3H4Explanation
C3H4 is an example of alkynes because it has a triple bond between two carbon atoms. Alkynes are hydrocarbons that contain at least one triple bond between carbon atoms. In this case, C3H4 has three carbon atoms and one triple bond, making it an alkyne. C3H8, C3H6, and C4H8 do not have triple bonds and are not examples of alkynes.Rate this question:
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- 18.
In ozonolysis of benzene how many molecules of ozone are added?
- A.
1
- B.
2
- C.
3
- D.
4
Correct Answer
C. 3Explanation
In ozonolysis of benzene, three molecules of ozone are added. This process involves the reaction of benzene with ozone, resulting in the formation of three molecules of cyclohexadienone and three molecules of oxygen. This reaction is commonly used in organic chemistry to introduce oxygen functionalities into benzene rings.Rate this question:
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- 19.
Aromatic compounds burn with:
- A.
Blue flame
- B.
Green flame
- C.
Red flame
- D.
Sooty flame
Correct Answer
D. Sooty flameExplanation
Aromatic compounds burn with a sooty flame because they contain a high amount of carbon. When these compounds burn, incomplete combustion occurs, leading to the production of black soot. The soot particles are visible in the flame, giving it a dark and smoky appearance.Rate this question:
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- 20.
Benzene reacts with methyl chloride in the presence of anhydrous aluminum chloride to give:
- A.
Toluene
- B.
Ethyl benzene
- C.
Isopropyl benzene
- D.
Chlorobenzene
Correct Answer
A. TolueneExplanation
Benzene reacts with methyl chloride in the presence of anhydrous aluminum chloride to give toluene. This reaction is known as Friedel-Crafts alkylation, where the methyl group from methyl chloride is transferred to the benzene ring. Toluene is formed as a result of this substitution reaction, where the methyl group replaces one of the hydrogen atoms in the benzene ring.Rate this question:
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Mar 20, 2023Quiz Edited by
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Apr 19, 2020Quiz Created by
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