datavorous/entrance-exam-dataset huggingface dataset:
Which of the following polymer is a polyamide ?

Options:
A
Terylene

B
Nylon

C
Rubber

D
Vulcanised rubber

The correct answer is:
Nylon

Solution:
Nylon is a polyamide fibre. It is prepared by the condensation polymerisation of adipic acid (HOOC. $\left.\left(\mathrm{CH}_2\right)_4 \mathrm{COOH}\right)$ and hexamethylene diamine $\left(\mathrm{H}_2 \mathrm{~N} \cdot\left(\mathrm{CH}_2\right)_6 \cdot \mathrm{NH}_2\right)$.

Topic: Chemistry, Polymers, JEE Main, JEE Main 2013 (23 Apr Online)
Which of the following polymer is formed by chain growth polymerisation process?

Options:
A Nylon-6, \( 6 \)
B Bakelite
C Terylene
D Teflon

The correct answer is:
Teflon

Solution:
Condensation reaction proceeds via step-growth polymerisation and addition reaction proceed through chain-growth polymerisation.

Nylon-6, 6 is synthesized by polycondensation reaction of hexamethylenediamine and adipic acid. Hence, undergo a step-growth mechanism.
Bakelite forms in a condensation reaction of phenol and formaldehyde. Hence, undergo a step-growth mechanism.
Terylene is a condensation polymer of ethylene glycol and terephthalic acid. Therefore it will also proceed via step growth.
Teflon is manufactured by heating tetrafluoroethene with a free radical or persulphate catalyst at high pressures. Teflon is an addition polymer of CF2=CF2. so, it will be formed by chain growth polymerisation.

Topic: Chemistry, Polymers, JEE Main
Which of the following polymer is not a synthetic rubber?

Options:
A Buna-S
B Thiokol
C Teflon
D Neoprene

The correct answer is:
Teflon

Solution:
Synthetic rubber is an artificial elastomer. In elastomeric polymers, the polymer chains are held together by the weak intermolecular forces. These weak binding forces permit the polymer to be stretched.

Teflon is manufactured by heating tetrafluoroethylene with a free radical or persulphate catalyst at high pressures. Hence, Teflon is thermoplastic. Teflon is not a synthetic rubber.

Topic: Chemistry, Polymers, JEE Main
Which of the following polymer is used in the manufacture of wood laminates ?

Options:
A cis-poly isoprene
B Melamine formaldehyde resin
C Urea formaldehyde resin
D Phenol and formaldehyde resin

The correct answer is:
Urea formaldehyde resin

Solution:
Urea-formaldehyde (UF) resin, one of the most important formaldehyde resin adhesives, is a polymeric condensation product of formaldehyde with urea, and being widely used for the manufacture of wood-based composite panels, such as plywood, particleboard, and fiberboard.

Urea -HCHO resin is used in manufacture of wood laminates.

Topic: Chemistry, Polymers, JEE Main, JEE Main 2021 (16 Mar Shift 2)
Which of the following polymers are correctly matched?

Options:
A 1, 2
B 3, 4
C 1, 3, 4
D 1, 2, 3, 4

The correct answer is:
1, 3, 4

Solution:
Accept terylene (2) rest are correctly matched. The correct structure of Terylene is given below

Topic: Chemistry, Polymers, JEE Main
Which of the following polymers is synthesized using a free radical polymerization technique?

Options:
A Terylene
B Melamine polymer
C Nylon 6, 6
D Teflon

The correct answer is:
Teflon

Solution:
Terylene, Melamine and Nylon-6, 6 are condensation polymers.

Teflon is addition polymer as monomer is alkene derivative CF2=CF2

Topic: Chemistry, Polymers, JEE Main, JEE Main 2016 (10 Apr Online)
Which of the following potential energy (P.E.) diagrams represents the SN1 reaction?

Options:
A
B
C
D

The correct answer is:

Solution:
P.E. diagram for SN1
SN1 is two step reaction where in step 1 formation of carbocation is RDS.

Topic: Chemistry, Haloalkanes and Haloarenes, JEE Main, JEE Main 2019 (09 Apr Shift 2)
Which of the following presents the correct order of second ionization enthalpies of $\mathrm{C}, \mathrm{N}, \mathrm{O}$ and $\mathrm{F}$ ?

Options:
A
F $>\mathrm{O}>\mathrm{N}>\mathrm{C}$

B
O $>$ N $>$ F $>$ C

C
$\mathrm{C}>\mathrm{N}>\mathrm{O}>\mathrm{F}$

D
O $>$ F $>$ N $>$ C

The correct answer is:
O $>$ F $>$ N $>$ C

Solution:
In a period the value of ionisation potential increases from left to right with breaks where the atoms have some what stable configuration. After removing an $e^{-}$ oxygen will acquire stable configuration. Hence $\mathrm{O}^{+}$has highest second ionisation enthalpy than $\mathrm{F}^{+}$and $\mathrm{N}^{+}$.
$\therefore$ correct order is $\mathrm{O}>\mathrm{F}>\mathrm{N}>\mathrm{C}$

Topic: Chemistry, Classification of Elements and Periodicity in Properties, JEE Main, JEE Main 2012 (26 May Online)
Which of the following process involves smelting?

Options:
A ZnCO3→ΔZnO+CO2
B Fe2O3+3C→Heat2Fe+3CO
C 2 PbS+3O2→Heat2PbO+2SO2
D Al2O3. 2H2O→HeatAl2O3+2H2O

The correct answer is:
Fe2O3+3C→Heat2Fe+3CO

Solution:
We know that smelting is reduction with carbon. Here Fe 2 O 3 with the help of carbon.

Topic: Chemistry, General Principles and Processes of Isolation of Metals, JEE Main
Which of the following process is used in the extractive metallurgy of magnesium?

Options:
A Fused salt electrolysis
B Self-reduction
C Aqueous solution electrolysis
D Thermite reduction

The correct answer is:
Fused salt electrolysis

Solution:
Magnesium is a strong electropositive metal. Hence its fused salt is used as electrolyte.

Topic: Chemistry, General Principles and Processes of Isolation of Metals, JEE Main
Which of the following processes are based on adsorption?
a. Separation of noble gases using coconut charcoal
b. Thin layer chromatography
c. Concentration of sulphide ore by froth floatation
d. Reduction of ethene using \( \mathrm{Ni}-\mathrm{Al} \) Alloy/ \( \mathrm{NaOH} \)
e. Formation of delta where the river meets the sea

Options:
A \( \mathrm{a}, \mathrm{b} \& \mathrm{c} \) but not \( \mathrm{d} \& \mathrm{e} \)
B \( c, d \& \) e but not a \& b
C \( \mathrm{a}, \mathrm{d} \& \mathrm{e} \) but not \( \mathrm{b} \& \mathrm{c} \)
D \( a, b, c \& d \) but not e

The correct answer is:
\( a, b, c \& d \) but not e

Solution:
Noble gases are adsorbed by charcoal, based on temperature region a particular noble gas is adsorbed and can be separated.

Solute particles in solution are adsorbed over stationary phase in thin layer chromatography.

By using pine oil in the froth flotation process, sulphide ore is concentrated by separating it from silica and earthy matter.

Ethene is in the gaseous phase and adsorbs over Ni.

River water is a colloidal solution of clay which on meeting the electrolyte of sea undergoes coagulation.

Topic: Chemistry, Surface Chemistry, JEE Main
Which of the following processes involves smelting

Options:
A ZnCO 3 → ZnO+CO 2
B Fe 2 O 3  + 3C→2Fe + 3CO
C 2PbS +  3O 2 →2PbO +  2SO 2
D Al 2 O 3 .2H 2 O→ Al 2 O 3  +  2H 2 O

The correct answer is:
Fe 2 O 3  + 3C→2Fe + 3CO

Solution:
Reduction with carbon is called smelting
Fe 2 O 3  + 3C→2Fe + 3CO

Topic: Chemistry, General Principles and Processes of Isolation of Metals, JEE Main
Which of the following processes play a part in the formation of a rainbow?
(i) Refraction
(ii) Total internal reflection
(iii) Dispersion
(iv) Interference

Options:
A
(i), (ii) and (iii)

B
(i) and (ii)

C
(i), (ii) and (iv)

D
(iii) and (iv)

The correct answer is:
(i), (ii) and (iii)

Solution:
Rainbow is formed due to the dispersion of light suffering refraction and total internal reflection (TIR) in the droplets present in the atmosphere.

Topic: Physics, Ray Optics, JEE Main, JEE Main 2012 (07 May Online)
Which of the following products can be formed when 2-chloro-2-methylpentane reacts with sodium methoxide in methanol ?

1.
2.
3.

Options:
A 3 only
B 1 and 2
C 1 and 3
D 1, 2 and 3

The correct answer is:
1, 2 and 3

Solution:
possible mechanism which takes place is E2 and S N 1 mechanism. Hence possible products are

Topic: Chemistry, Haloalkanes and Haloarenes, JEE Main
Which of the following products is formed when benzaldehyde is treated with $\mathrm{CH}_3 \mathrm{MgBr}$ and the addition product so obtained is subjected to acid hydrolysis

Options:
A Secondary alcohol
B A primary alcohol
C Phenol
D Tert-Butyl alcohol

The correct answer is:
Secondary alcohol

Solution:
\(\underset{\text{Benzaldehyde}}{\mathrm{C}_6 \mathrm{H}_5 \mathrm{CHO}} \xrightarrow[\mathrm{H}^{+} / \mathrm{H}_2 \mathrm{O}]{\mathrm{CH}_3 \mathrm{Mg} \mathrm{O}} \underset{2^\circ \text{Alcohol}}{\mathrm{C}_6 \mathrm{H}_5 \mathrm{CH}(\mathrm{OH}) \mathrm{CH}_2}\)

Topic: Chemistry, Aldehydes and Ketones, JEE Main
Which of the following properties is not true for an alkali metal

Options:
A Low atomic volume
B Low ionization energy
C Low density
D Low electronegativity

The correct answer is:
Low atomic volume

Solution:
They possess highest atomic volume in their respective periods.

Topic: Chemistry, s Block Elements, JEE Main
Which of the following properties show gradual decrease with increase in atomic number across a period in the periodic table

Options:
A Electron affinity
B Ionization potential
C Electronegativity
D Size of atom

The correct answer is:
Size of atom

Solution:
It is a fact.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, JEE Main
Which of the following property displays progressive increase down a group in the Bohr's periodic table

Options:
A Electronegativity
B Electron affinity
C Ionization potential
D Size of the atom

The correct answer is:
Size of the atom

Solution:
In completely filled shell inter atomic repulsion is more so have greater size.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, JEE Main
Which of the following public health measures, as safeguard against infectious diseases?

Options:
A Drinking cold water
B Maintenance of personal and public hygiene
C Visiting doctor every week
D None of the above

The correct answer is:
Maintenance of personal and public hygiene

Solution:
Maintenance of personal and public hygiene is one of the public health measures to safeguard against infectious diseases.

Topic: Biology, Human Health and Diseases, NEET
Which of the following quantities do not change when a resistor connected to a battery is heated due to the current?

Options:
A Drift speed
B Resistivity
C Resistance
D Number of free electrons

The correct answer is:
Number of free electrons

Solution:
Only number of free electrons is constant, other factors are temperature dependent.

Topic: Physics, Current Electricity, JEE Main
Which of the following radiations has the least wavelength?

Options:
A
$\gamma$-rays

B
$\beta$-rays

C
$\alpha$-rays

D
X-rays

The correct answer is:
$\gamma$-rays

Solution:
$\mathrm{R} \rightarrow$ Radio waves ; $\mathrm{M} \rightarrow$ Micro waves; $\quad \mathrm{I} \rightarrow$ Infra red rays; $\mathrm{V} \rightarrow$ Visible rays; $\mathrm{U} \rightarrow$ Ultraviolet rays; $\mathrm{X} \rightarrow \mathrm{X}$ rays; $\quad \mathrm{G} \rightarrow \gamma$ rays; $\quad \mathrm{C} \rightarrow$ Cosmic rays
$\Rightarrow \gamma$ rays has least wavelength

Topic: Physics, Nuclear Physics, JEE Main, JEE Main 2003
Which of the following rate laws has an overall order of 0.5 for reaction involving substances $x, y$ and $z$

Options:
A Rate $=K\left(C_x\right)\left(C_y\right)\left(C_z\right)$
B Rate $=K\left(C_x\right)^{0.5}\left(C_y\right)^{0.5}\left(C_z\right)^{0.5}$
C Rate $=K\left(C_x\right)^{1.5}\left(C_y\right)^{-1}\left(C_z\right)^0$
D Rate $=K\left(C_x\right)\left(C_z\right)^n /\left(C_y\right)^2$

The correct answer is:
Rate $=K\left(C_x\right)^{1.5}\left(C_y\right)^{-1}\left(C_z\right)^0$

Solution:
Order of reaction is sum of the power raised on concentration terms to express rate expression.

Topic: Chemistry, Chemical Kinetics, JEE Main
Which of the following rays are not electromagnetic waves?

Options:
A X-rays
B $\gamma$-rays
C $\beta$-rays
D heat rays

The correct answer is:
$\beta$-rays

Solution:
$\beta$-rays are not electromagnetic waves.

Topic: Physics, Electromagnetic Waves, JEE Main
Which of the following reaction DOES NOT involve Hoffmann Bromamide degradation ?

Options:
A
B
C
D

The correct answer is:

Solution:
Hoffmann Bromanide degradation is conversion of amide to amine with one less no. of carbon atom. Only 1°amides undergo this reaction.

This reaction does not involve haffmann bromanide degradation Rest all options involve haffmann bromamide degradation during the reaction of Br2 + NaOH with amide.

Topic: Chemistry, Amines, JEE Main, JEE Main 2021 (16 Mar Shift 1)
Which of the following reaction does not occur spontaneously?

Options:
A Fe+3+CdâCd+2+Fe+2
B Fe +3 + I − → Fe +2 + I 2
C Fe +2 + MnO 4 − → H + Fe +3 + Mn +2
D Fe+3+Ce+3âFe+2+Ce+4

The correct answer is:
Fe+3+Ce+3→Fe+2+Ce+4

Solution:
Ce+4 is a strong oxidising agent so the reverse reaction takes place
Ce+4+Fe+2→Ce+3+Fe+3

Topic: Chemistry, d and f Block Elements, JEE Main
Which of the following reaction follows Anti-Markovnikov's addition?

Options:
A \( \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HBr} \stackrel{\text { peroxide }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CHBr}-\mathrm{CH}_{3} \)
B \( \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HBr} \stackrel{\text { peroxide }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br} \)
C \( \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HCl} \stackrel{\text { peroxide }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CHClCH}_{3} \)
D \( \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HI} \stackrel{\text { peroxide }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CHI}-\mathrm{CH}_{3} \)

The correct answer is:
\( \mathrm{CH}_{3} \mathrm{CH}=\mathrm{CH}_{2}+\mathrm{HBr} \stackrel{\text { peroxide }}{\longrightarrow} \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br} \)

Solution:
Anti-Markovnikov rule or peroxide effect is only observed in case of HBr and also in presence of peroxide.

CH3-CH=CH2+HBr →peroxide CH3-CH2CH2Br

Topic: Chemistry, Hydrocarbons, JEE Main
Which of the following reaction is a redox reaction

Options:
A $\mathrm{P}_2 \mathrm{O}_5+2 \mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{H}_4 \mathrm{P}_2 \mathrm{O}_7$
B $2 \mathrm{AgNO}_3+\mathrm{BaCl}_2 \rightarrow 2 \mathrm{AgCl}+\mathrm{Ba}\left(\mathrm{NO}_3\right)_2$
C $\mathrm{BaCl}_2+\mathrm{H}_2 \mathrm{SO}_4 \rightarrow \mathrm{BaSO}_4+2 \mathrm{HCl}$
D $\mathrm{Cu}+2 \mathrm{AgNO}_3 \rightarrow 2 \mathrm{Ag}+\mathrm{Cu}\left(\mathrm{NO}_3\right)_2$

The correct answer is:
$\mathrm{Cu}+2 \mathrm{AgNO}_3 \rightarrow 2 \mathrm{Ag}+\mathrm{Cu}\left(\mathrm{NO}_3\right)_2$

Solution:
$\mathrm{Cu}+2 \mathrm{AgNO}_3 \rightarrow \mathrm{Cu}\left(\mathrm{NO}_3\right)_2+2 \mathrm{Ag}$. This is a redox reaction.

Topic: Chemistry, Redox Reactions, JEE Main
Which of the following reaction is an example of ammonolysis?

Options:
A C6H5COCl+C6H5NH2⟶C6H5CONHC6H5
B C6H5CH2CN⟶[H]C6H5CH2CH2NH2
C C6H5NH2⟶HClC6H5NH3Cl-
D C6H5CH2Cl+NH3⟶C6H5CH2NH2

The correct answer is:
C6H5CH2Cl+NH3⟶C6H5CH2NH2

Solution:
The process of cleavage of the C-X bond by Ammonia molecule is known as ammonolysis.

Ex: R-CH2-Cl+N¨H3⟶R-CH2-NH2

Topic: Chemistry, Amines, JEE Main, JEE Main 2021 (17 Mar Shift 1)
Which of the following reaction is correct?

Options:
A
B
C
D C2H5CONH2+Br2+NaOH→C2H5CH2NH2+Na2CO3+NaBr+H2O

The correct answer is:

Solution:
The Markovnikov Rule predicts the regiochemistry of HX addition to unsymmetrically substituted alkenes. The halide component of HX bonds preferentially at the more highly substituted carbon, whereas hydrogen prefers the carbon which already contains more hydrogen.

By the reaction withHNO2 amine doesnot lose any carbon while producing alcohol.

CH3CH2CH2NH2→HNO2/0-5oCCH3CH2CH2OH+N2+HCl

Cyclohexene undergo allylic substitution reaction with bromine in the presence of sunlight.

In Hoffmann bromamide degradation amides give amines by loss of one carbon.

C2H5CONH2+Br2+NaOH→C2H5NH2+Na2CO3+NaBr+H2O

Topic: Chemistry, Amines, JEE Main, JEE Main 2024 (29 Jan Shift 2)
Which of the following reaction is correct?

Options:
A 2LiNO3⟶Δ2LiNO2+O2
B 4LiNO3⟶Δ2Li2O+2N2O4+O2
C 4LiNO3⟶Δ2Li2O+4NO2+O2
D 2LiNO3⟶Δ2Li+2NO2+O2

The correct answer is:
4LiNO3⟶Δ2Li2O+4NO2+O2

Solution:
Lithium nitrate when decomposed, the product formed are Li2O, NO2 and O2. The remaining alkali metal nitrates decomposes to nitrite of metals and oxygen gas. It is due to the lithium monoxide is stable than other monoxides.

4LiNO3⟶Δ2Li2O+4NO2+O2

Topic: Chemistry, s Block Elements, JEE Main, JEE Main 2023 (30 Jan Shift 2)
Which of the following reaction is feasible?

Options:
A

B $\mathrm{H}_3 \mathrm{CCH}=\mathrm{CHCH}_2 \mathrm{OH} \stackrel{\mathrm{PCC}}{\longrightarrow} \mathrm{H}_3 \mathrm{CCH}=\mathrm{CHCHO}$
C $\mathrm{CH}_3 \mathrm{CH}_2 \mathrm{CH}_2 \mathrm{OH} \stackrel{\mathrm{KMnO}_4}{\mathrm{H}^{+}} \mathrm{H}_3 \mathrm{CCH}_2 \mathrm{CHO}$
D

The correct answer is:
$\mathrm{H}_3 \mathrm{CCH}=\mathrm{CHCH}_2 \mathrm{OH} \stackrel{\mathrm{PCC}}{\longrightarrow} \mathrm{H}_3 \mathrm{CCH}=\mathrm{CHCHO}$

Solution:
Reaction in (a) is not feasible because replacement of $-\mathrm{OH}$ by $-\mathrm{Cl}$ is not possible for phenol due to partial $\mathrm{C}$ $=\mathrm{O}$ bond and resonance stabilization.
Reaction is (c) is not feasible because $\mathrm{KMnO}_4$ is a strong oxidizing agent and converts $-\mathrm{C}-\mathrm{OH}$ to $-\mathrm{COOH}$.
Reaction in (d) is not feasible because $20 \% \mathrm{PO}_4$ is not a strong enough dehydrating agent and therefore $85 \% \mathrm{~h}_3$ $\mathrm{PO}_4$ is used.

Topic: Chemistry, Carboxylic Acid Derivatives, JEE Main
Which of the following reaction is involved in the preparation of primary amines:
(i) Hofmann’s bromamide reaction and
(ii) Gobriel phthalimide synthesis

Options:
A (i)
B (ii)
C Both of these
D None of these

The correct answer is:
Both of these

Solution:
(i) Hofmannâs bromamide reaction: The conversion of a primary amide to a primary amine, containing one carbon atom less than the original amide, on heating with a mixture of Br 2 in presence of NaOH is called Hofmannâs bromide reaction
CH 3 CONH 2 + Br 2 +4NaOHââ CH 3 â NH 2 +2NaBr+ Na 2 â CO 3 +2 H 2 âO AcetamideââââââââââââââââââââââââââââââââââââââââââââMethylamine
(ii) Gabriel phthalimide reaction: This is a very convenient method for the preparation of pure aliphatic and aryl primary amines.

Topic: Chemistry, Amines, JEE Main
Which of the following reaction is not feasible

Options:
A $2 \mathrm{KI}+\mathrm{Br}_2 \rightarrow 2 \mathrm{KBr}+\mathrm{I}_2$
B $2 \mathrm{H}_2 \mathrm{O}+2 \mathrm{~F}_2 \rightarrow 2 \mathrm{HF}+\mathrm{O}_2$
C $2 \mathrm{KBr}+\mathrm{I}_2 \rightarrow 2 \mathrm{Kl}+\mathrm{Br}_2$
D $2 \mathrm{KBr}+\mathrm{Cl}_2 \rightarrow 2 \mathrm{KCl}+\mathrm{Br}_2$

The correct answer is:
$2 \mathrm{KBr}+\mathrm{I}_2 \rightarrow 2 \mathrm{Kl}+\mathrm{Br}_2$

Solution:
$2 \mathrm{KBr}+\mathrm{I}_2 \rightarrow 2 \mathrm{Kl}+\mathrm{Br}_2$

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), JEE Main
Which of the following reaction is possible at anode?

Options:
A
$2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}$

B
$\mathrm{F}_2 \rightarrow 2 \mathrm{~F}^{-}$

C
$(1 / 2) \mathrm{O}_2+2 \mathrm{H}^{+} \rightarrow \mathrm{H}_2 \mathrm{O}$

D
none of these

The correct answer is:
$2 \mathrm{Cr}^{3+}+7 \mathrm{H}_2 \mathrm{O} \rightarrow \mathrm{Cr}_2 \mathrm{O}_7^{2-}+14 \mathrm{H}^{+}$

Solution:
No Solution Available

Topic: Chemistry, Electrochemistry, JEE Main, JEE Main 2002
Which of the following reaction is taking place resulting in discolouration of marble of the buildings like Taj Mahal?

Options:
A CaCO3+H2SO4→CaSO4+H2O+CO2
B CaCO3+2HCl→CaCl2+H2O+CO2
C CaCO3+H2O→CaOH2+CO2
D CaCO3→CaO+CO2

The correct answer is:
CaCO3+H2SO4→CaSO4+H2O+CO2

Solution:
High level of sulphur and nitrogen oxides cause acid rain which reacts with marble to decolourise it.

Topic: Chemistry, s Block Elements, JEE Main
Which of the following reaction is/are feasible?

Options:
A
B
C Both (a) and (b)
D None of the above

The correct answer is:

Solution:
S N 2 reaction can easily take place on primary alkyl halides.

Topic: Chemistry, Alcohols Phenols and Ethers, JEE Main
Which of the following reaction produce alkane as the product?

Options:
A I, II, III
B I, III, IV
C I, II, IV
D II, III, IV

The correct answer is:
I, II, IV

Solution:
(I)
The mixture of $\mathrm{NaOH}+\mathrm{CaO}$ is called sodalime when it reacts with sodium salt of carboxylic acid, it gives corresponding alkane. The reaction is called decarboxylation of salts of carboxylic acids.
(I) $\mathrm{R}-\mathrm{COO}{ }^{+}+\mathrm{NaOH} \underset{\Delta}{\stackrel{\mathrm{CaO}}{\longrightarrow}} \underset{\substack{\text { (Alkane }\}}}{(R-\mathrm{H})}$
(II)
The above reaction is called Clemmensen-reduction. It converts aldehydes and ketones to corresponding alkane.
(III)
This reaction is used for reduction of alkynes which gives corresponding alkenes.
This reaction is used for reduction of alkynes which gives corresponding alkenes.
(iv)
Hence, option (3) is the correct answer.

Topic: Chemistry, Hydrocarbons, JEE Main
Which of the following reactions and facts of D -glucose cannot be explained by its open chain structure?

(i) Despite having the aldehyde group, glucose does not give Schiff test and 2,4-DNP test.

(ii) Glucose does not react with sodium hydrogen sulphite to form addition product.

(iii) The pentaacetate of glucose does not react with hydroxyl amine showing the absence of free- CHO group.

Options:
A

(i)

B

(ii)

C

(iii)

D

All of above

The correct answer is:

All of above

Solution:
The above behaviour could not be explained by the open chain structure. Because one of the –OH groups of glucose add to the –CHO group and form a cyclic hemiacetal structure. It was found that glucose forms a six membered ring in which –OH at C-5 is involved in ring formation. This explains the absence of –CHO group.

Topic: Chemistry, Biomolecules, JEE Main
Which of the following reactions are disproportionation reactions?

1 Cu+→Cu2++Cu

2 3MnO42-+4H+→2MnO4-+MnO2+2H2O

3 2KMnO4→K2MnO4+MnO2+O2

4 2MnO4-+3Mn2++2H2O→5MnO2+4H+

Choose the correct answer from the options given below:

Options:
A 1, 2
B 2, 3, 4
C 1, 2, 4
D 1, 4

The correct answer is:
1, 2

Solution:
In disproportionation reaction, both oxidation and reduction of same chemical species occurs.

Oxidation is gain in oxidation number.

Reduction is loss in oxidation number.

1) Cu+⟶Cu2++Cu

Oxidation state of Cu+=+1.

Oxidation state of Cu2+=+2.

Oxidation state of Cu=0 .

Here, Cu+ is getting both reduced and oxidised.

2) 3MnO4-+4H+⟶2MnO4-+MnO2+2H2O

Oxidation state of Mn in MnO4-=+7.

Oxidation state of Mn in MnO2 =+4.

Here, reduction is taking place.

3) 2KMnO4⟶K2MnO4+MnO2+O2

Here in the reaction, Mn is changing its oxidation state from +7 to +6 and +4. In both cases, reduction is occurring.

4) 2MnO4-+3Mn2++2H2O⟶5MnO2+4H+

Here in the reaction, product with Mn in only one, so there is no possibility of both oxidation and reduction reactions at the same time.

Topic: Chemistry, Redox Reactions, JEE Main, JEE Main 2024 (01 Feb Shift 1)
Which of the following reaction(s) can be used for the preparation of alkyl halides?

I. CH3CH2OH+HClâAnhyd. ZnCl2

II. CH3CH2OH+HClâ¶

III. CH33COH+HClâ¶

IV. CH32CHOH+HClâAnhyd. ZnCl2

Options:
A I III and IV only
B I and II only
C IV only
D III and IV only

The correct answer is:
I III and IV only

Solution:
I and IV can be used due to presence of anhydrous ZnCl2
(III) which gives alkyl halide due to formation of more stable carbocation.

Topic: Chemistry, Haloalkanes and Haloarenes, JEE Main
Which of the following reactions can be used to prepare ketones from secondary alcohols?

Options:
A Reduction with $\mathrm{LiAlH}_4$
B Oxidation with PCC
C Oxidation with $\mathrm{KMnO}_4$
D Dehydration with $\mathrm{H}_2 \mathrm{SO}_4$

The correct answer is:
Oxidation with $\mathrm{KMnO}_4$

Solution:
Oxidation with $\mathrm{KMnO}_4$
Explanation: $\mathrm{KMnO}_4$ is a strong oxidizing agent that can oxidize secondary alcohols to ketones.

Topic: Chemistry, Aldehydes and Ketones, JEE Main