CSIR-NET chemical science MCQs questions with Aptitude MCQ
MCQ with proper solutions FOR CSIR-NET JUNE 2023
Understand the Exam Pattern: Before starting your preparation, make sure you are familiar with the exam pattern.
here are some CSIR-NET General Aptitude MCQs from previous years with solutions:
The radius of a circle is decreased by 10%. By what percent does its area decrease?
Solution:
Let the original radius be 'r' and original area be 'A'.
New radius = 0.9r
New area = π(0.9r)^2 = 0.81πr^2
Percentage decrease in area = [(A-New area)/A] x 100%
= [(A-0.81πr^2)/A] x 100%
= [0.19πr^2/A] x 100%
= 19%
Answer: 19%
The total age of A and B is 12 years more than the total age of B and C. C is how many years younger than A?
Solution:
Let the ages of A, B, and C be A, B, and C respectively.
According to the problem, we have:
A + B = B + C + 12 (Total age of A and B is 12 years more than the total age of B and C)
Simplifying, we get:
A - C = 12
Therefore, C is 12 years younger than A.
Answer: 12 years
If the selling price of an article is 25% more than its cost price, then the profit percentage is:
Solution:
Let the cost price of the article be 'x'
Selling price = x + 25% of x = 1.25x
Profit = Selling price - Cost price = 1.25x - x = 0.25x
Profit percentage = (Profit/Cost price) x 100%
= (0.25x/x) x 100%
= 25%
Answer: 25%
If 10 men can complete a work in 20 days, how many days will 15 men take to complete the same work?
Solution:
Let the work to be done be '1 unit'
So, 10 men can do the work in 20 days, i.e., they can do 1/20 of the work in a day.
15 men can do the work in (10/15) x 20 = 40/3 days
So, 15 men can do 1/20 of the work in a day.
Therefore, 15 men can complete the work in (20/3) days.
Answer: 20/3 days
The average of 10 numbers is increased by 5. If one number is also increased by 5, then the new average is increased by:
Solution:
Let the sum of the 10 numbers be 'S'.
The original average = S/10
When the average is increased by 5, the new average is (S+50)/10
Let x be the number that is increased by 5.
The new sum of the 10 numbers = S+x+5
The new average = (S+x+5)/10
The difference between the new average and the old average = [(S+x+5)/10] - (S/10)
= (x+5)/10
Answer: (x+5)/10
A car covers the distance between two cities in 6 hours if it travels at a speed of 60 km/h. If the speed is increased by 20%, how much time will it take to cover the same distance?
Solution:
Let the distance between the two cities be 'd'.
Time taken by the car to cover the distance at a speed of 60 km/h = d/60
When the speed is increased by 20%,
Understand the Exam Pattern: Before starting your preparation, make sure you are familiar with the exam pattern
Optional MCQ with solutions from the previous CSIR NET CHEMICAL SCIENCE papers
Sure, here are 50 MCQs with solutions from previous CSIR NET Chemical Science papers:
Which of the following is not an electrophile?
a) HNO3
b) SO3
c) SOCl2
d) BF3
Solution:
b) SO3 is not an electrophile as it is an electron-deficient compound and cannot accept electrons.
Which of the following compounds shows the highest boiling point?
a) CH3CH2OH
b) CH3CH2CH3
c) CH3CH2Cl
d) CH3CH2OCH3
Solution:
a) CH3CH2OH shows the highest boiling point due to the presence of intermolecular hydrogen bonding between the molecules.
The de Broglie wavelength of an electron in the ground state of a hydrogen atom is approximately:
a) 3.3 × 10^-10 m
b) 6.6 × 10^-10 m
c) 1.2 × 10^-10 m
d) 2.5 × 10^-10 m
Solution:
d) The de Broglie wavelength of an electron in the ground state of a hydrogen atom is given by λ = h/p, where h is Planck's constant and p is the momentum of the electron. The momentum of the electron in the ground state is given by p = √(2mE), where m is the mass of the electron and E is the energy of the electron. Substituting the values, we get λ = 2.5 × 10^-10 m.
The isoelectronic series having the largest ionic radius is:
a) F^-, Ne, Na+, Mg2+
b) O2-, F^-, Ne, Na+
c) O2-, F^-, Ne, Na+, Mg2+
d) F^-, Ne, Na+, Mg2+, Al3+
Solution:
a) In an isoelectronic series, the ionic radius decreases with increasing atomic number. Among the given options, F^-, Ne, Na+, and Mg2+ are all isoelectronic with the same number of electrons. Na+ has the largest ionic radius due to the removal of an electron. Therefore, the correct option is (a).
Which of the following elements exhibits the highest first ionization energy?
a) Na
b) Mg
c) Al
d) Si
Solution:
d) Si exhibits the highest first ionization energy due to its smaller atomic size and higher nuclear charge compared to the other elements.
Which of the following compounds will show cis-trans isomerism?
a) CH2=CH2
b) CH3CH=CHCH3
c) CH3CH=CHCH2Cl
d) CH3CH=CHCHO
Solution:
c) CH3CH=CHCH2Cl will show cis-trans isomerism as it has a carbon-carbon double bond and two different groups (H and Cl) attached to each carbon.
The equilibrium constant (Kc) for the reaction N2O4(g) ⇌ 2NO2(g) is 4.65 × 10^-3 at 298 K. What is the value of the equilibrium constant (Kp) for the reaction at the same temperature?
a) 1.16 × 10^-3
b) 4.65 × 10^-3
c) 1.86 × 10^-2
d) 2.33 × 10^-1
Solution:
c) Kp = Kc(RT)^Δn, where Δn = number
Sure, here are 10 more MCQs with solutions from previous CSIR NET Chemical Science papers:
Which of the following compounds is most acidic?
a) CH3CH2OH
b) CH3CH2SH
c) CH3CH2NH2
d) CH3CH2Cl
Solution:
b) CH3CH2SH is the most acidic compound among the given options due to the presence of the sulfhydryl group, which is more acidic than the other functional groups.
The major product of the following reaction is:
CH3CH2CH=CH2 + H2O + H+ → ?
a) CH3CH2COOH
b) CH3CH2CH2OH
c) CH3CH2CHO
d) CH3CH2CH(OH)CH3
Solution:
a) The major product of the given reaction is CH3CH2COOH (propanoic acid) through hydration of the alkene.
The IUPAC name of the compound below is:
(CH3)2CHCH2C(CH3)3
a) 3,3,4-trimethylpentane
b) 2,3,4-trimethylpentane
c) 2,2,4-trimethylpentane
d) 2,2,5-trimethylpentane
Solution:
d) The IUPAC name of the compound is 2,2,5-trimethylpentane as the longest chain has five carbon atoms and the methyl groups are attached to the second and fifth carbon atoms.
The ratio of the radii of Na+ and Cl- is:
a) 1:2
b) 1:1
c) 2:1
d) 3:2
Solution:
c) The ratio of the radii of Na+ and Cl- is 2:1 as Na+ has lost an electron, resulting in a smaller size, while Cl- has gained an electron, resulting in a larger size.
The pH of a solution containing 0.01 M HCl is:
a) 1
b) 2
c) 3
d) 4
Solution:
a) The pH of a solution containing 0.01 M HCl is 2, as HCl is a strong acid and completely ionizes in water to give H+ ions.
Which of the following statements is not true for enzymes?
a) They increase the rate of a chemical reaction.
b) They are highly specific.
c) They are consumed during the reaction.
d) They are biological catalysts.
Solution:
c) Enzymes are not consumed during a reaction, as they only increase the rate of the reaction without being changed themselves.
The hybridization of the carbon atoms in methane (CH4) is:
a) sp
b) sp2
c) sp3
d) sp3d
Solution:
c) The hybridization of the carbon atoms in methane (CH4) is sp3, as the carbon atom is bonded to four hydrogen atoms using four hybrid orbitals.
Which of the following compounds has the highest boiling point?
a) CH3CH2OH
b) CH3OCH3
c) CH3CH2F
d) CH3CH2Cl
Solution:
a) CH3CH2OH has the highest boiling point due to the presence of intermolecular hydrogen bonding between the molecules.
Which of the following molecules has the largest bond angle?
a) H2O
b) NH3
c) CH4
d) SF6
Solution:
c) CH4 has the largest bond angle among the given options, which is 109.5°, due to the tetrahedral geometry of the molecule.
The IUPAC name of the following compound is:
CH3CH=CHCOOH
a) 2-propenoic acid
b) 3-propenoic acid
c) 2-butenic acid
d) 3-butenic acid
Solution:
c) The IUPAC name of the compound is 2-butenic acid as the double bond is between the second and third carbon atoms.
The unit of molar conductivity is:
a) Sm^2/mol
b) S/cm
c) S/m
d) Sm/mol
Solution:
b) The unit of molar conductivity is S/cm.
Which of the following statements is true about the Gibbs free energy change?
a) It is always negative for spontaneous processes.
b) It is always positive for spontaneous processes.
c) It can be either positive or negative for spontaneous processes.
d) It is always zero for spontaneous processes.
Solution:
a) The Gibbs free energy change is always negative for spontaneous processes as it represents the maximum amount of work that can be obtained from a reaction.
The strongest reducing agent among the following is:
a) H2
b) Zn
c) Cu
d) Ag
Solution:
a) H2 is the strongest reducing agent among the given options, as it has the lowest reduction potential and can reduce almost any other species.
The compound which can exhibit cis-trans isomerism is:
a) CH3CH=CH2
b) CH3CH2CH=CH2
c) CH3CH=CHCH3
d) CH3CH2CH2CH=CH2
Solution:
d) CH3CH2CH2CH=CH2 is the compound that can exhibit cis-trans isomerism, as it has a carbon-carbon double bond and four different substituents.
Which of the following is a Lewis acid?
a) H2O
b) Cl2
c) NH3
d) BF3
Solution:
d) BF3 is a Lewis acid, as it is an electron-deficient species that can accept a pair of electrons from a Lewis base.
The number of water molecules present in Mohr's salt (FeSO4(NH4)2SO4.6H2O) is:
a) 2
b) 4
c) 6
d) 8
Solution:
c) The number of water molecules present in Mohr's salt is 6.
The IUPAC name of the following compound is:
C6H5COCH(CH3)2
a) 1-phenylpropanone
b) 1-phenyl-2-propanone
c) 2,2-dimethyl-1-phenylpropanone
d) 2,2-dimethyl-1-phenyl-2-propanone
Solution:
c) The IUPAC name of the compound is 2,2-dimethyl-1-phenylpropanone as the ketone group is attached to the second carbon atom and the two methyl groups are attached to the second and third carbon atoms.
The number of optical isomers of the following compound is:
C6H5CH(OH)COOH
a) 0
b) 1
c) 2
d) 3
Solution:
c) The number of optical isomers of the compound is 2, as it has a single chiral carbon atom.
Which of the following compounds will show geometrical isomerism?
a) CH3CH2CH2NH2
b) CH3CH2CH2COOH
c) CH3CH=CHCH2OH
d) CH3CH=CHCN
Solution:
c) CH3CH=CHCH2OH will show geometrical isomerism, as it has a carbon-carbon double bond and two different substituents.
The product of the reaction of ethylene with HBr in the presence of peroxide is:
a) ethyl bromide
b) propene
c) 1,2-dibromoethane
d) 1,1-dibromoethane
Solution:
d) The product of the reaction is 1,1-dibromoethane, as the reaction proceeds via the formation of a bromonium ion intermediate.
Aptitude Questions
The radius of a circle is decreased by 10%. By what percent does its area decrease?
Solution:
Let the original radius be 'r' and original area be 'A'.
New radius = 0.9r
New area = π(0.9r)^2 = 0.81πr^2
Percentage decrease in area = [(A-New area)/A] x 100%
= [(A-0.81πr^2)/A] x 100%
= [0.19πr^2/A] x 100%
= 19%
Answer: 19%
The total age of A and B is 12 years more than the total age of B and C. C is how many years younger than A?
Solution:
Let the ages of A, B, and C be A, B, and C respectively.
According to the problem, we have:
A + B = B + C + 12 (Total age of A and B is 12 years more than the total age of B and C)
Simplifying, we get:
A - C = 12
Therefore, C is 12 years younger than A.
Answer: 12 years
If the selling price of an article is 25% more than its cost price, then the profit percentage is:
Solution:
Let the cost price of the article be 'x'
Selling price = x + 25% of x = 1.25x
Profit = Selling price - Cost price = 1.25x - x = 0.25x
Profit percentage = (Profit/Cost price) x 100%
= (0.25x/x) x 100%
= 25%
Answer: 25%
If 10 men can complete a work in 20 days, how many days will 15 men take to complete the same work?
Solution:
Let the work to be done be '1 unit'
So, 10 men can do the work in 20 days, i.e., they can do 1/20 of the work in a day.
15 men can do the work in (10/15) x 20 = 40/3 days
So, 15 men can do 1/20 of the work in a day.
Therefore, 15 men can complete the work in (20/3) days.
Answer: 20/3 days
The average of 10 numbers is increased by 5. If one number is also increased by 5, then the new average is increased by:
Solution:
Let the sum of the 10 numbers be 'S'.
The original average = S/10
When the average is increased by 5, the new average is (S+50)/10
Let x be the number that is increased by 5.
The new sum of the 10 numbers = S+x+5
The new average = (S+x+5)/10
The difference between the new average and the old average = [(S+x+5)/10] - (S/10)
= (x+5)/10
Answer: (x+5)/10
A car covers the distance between two cities in 6 hours if it travels at a speed of 60 km/h. If the speed is increased by 20%, how much time will it take to cover the same distance?
Solution:
Let the distance between the two cities be 'd'.
Time taken by the car to cover the distance at a speed of 60 km/h = d/60
When the speed is increased by 20%,
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