datavorous/entrance-exam-dataset huggingface dataset:
Which of the following oxoacids of sulphur contains "S" in two different oxidation states?

Options:
A H2S2O3
B H2S2O6
C H2S2O7
D H2S2O8

The correct answer is:
H2S2O3

Solution:
In this molecule both sulphur has different oxidation number one has -2 oxidation number and other has +6 oxidation number. Average oxidation number of sulphur will be +2.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), JEE Main, JEE Main 2022 (28 Jun Shift 2)
Which of the following oxyacid contains both P-H and P-P bond simultaneously?

Options:
A H4P2O5
B H4P2O7
C H4P2O6
D None of these

The correct answer is:
None of these

Solution:
P-P linkage exists when calculated oxidation number = maximum Ox. No. (i.e. 5) for P
H4P2O64= No P-H linkage.

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), JEE Main
Which of the following pair is expected to exhibit the same colour in solution?

Options:
A VOCl2 ; ZnSO4
B MnCl2 ; ZnSO4
C CuCl2 , HgCl2
D CuCl2 ; VOCl2

The correct answer is:
CuCl2 ; VOCl2

Solution:
In CuCl 2 , Cu 2+ has d 9 configuration, exhibit d-d transition and show colour. Similarly in VOCl 2 , V 4+ has d 1 configuration, can exhibit d-d transition and show colour.
MnCl 2 = Pink colour
Zn 2 + â 3d 1 0 Colourless
Hg 2 + â 5d 1 0 Colourless
V = 4 s 2 3 d 3
V 4 + = 4s 0 3d 1 (d - d transition)
Cu +2  =  d 9 configuration = 1 - unpaired e â electrons.
Since, in both CuCl 2 and VOCl 2 , Cu 2+ and V 4+ ion contain 1 unpaired electron each, so their colour may be same.

Topic: Chemistry, d and f Block Elements, JEE Main
Which of the following pair is not isoelectronic species?
(Atomic numbers Sm=62; Er=68; Yb=70; Lu=71; Eu=63; Tb=65; Tm=69)

Options:
A Sm2+ and Er3+
B Yb2+ and Lu3+
C Eu2+ and Tb4+
D Tb2+ and Tm4+

The correct answer is:
Tb2+ and Tm4+

Solution:
Isoelectronic species refers to two atoms, ions or molecules that have the same electronic structure and the same number of valence electrons term means "equal electric" or "equal charge". Isoelectronic chemical species typically display similar chemical properties.

Sm2+→electron=60Er3+→electron=65 Tb2+→electron=63Tm4+→electron=65 (not isoelectronic)

While Yb2+ and Lu3+ both will have 68 electrons. and Eu2+ and Tb4+ both will have 61 electrons.so, they are isoelectronic with each other.

Note: According to NTA only option D is given as answer but option A and D both will be the correct answer.

Topic: Chemistry, Structure of Atom, JEE Main, JEE Main 2022 (28 Jul Shift 2)
Which of the following pair of ions may exhibit same colour

Options:
A $\mathrm{Cr}^{+++}$and $\mathrm{Fe}^{++}$
B $T^{+++}$and $V^{++}$
C $\mathrm{V}^{4+}$ and $\mathrm{Mn}^{++}$
D $\mathrm{Fe}^{2+}$ and $\mathrm{Ni}^{+}$

The correct answer is:
$\mathrm{Cr}^{+++}$and $\mathrm{Fe}^{++}$

Solution:
Correct option is 1. $\mathrm{Cr}^{+++}$and $\mathrm{Fe}^{++}$
$\mathrm{Cr}^{+++}$and $\mathrm{Fe}^{++}$is the pair of ions which exhibit almost the same colour
$\mathrm{Cr}^{3+} \rightarrow$ green
$F e^{2+} \rightarrow$ pale - green

Topic: Chemistry, d and f Block Elements, JEE Main
Which of the following pair of molecules contain odd electron molecule and an expanded octet molecule?

Options:
A BCl3 and SF6
B NO and H2SO4
C SF6 and H2SO4
D BCl3 and NO

The correct answer is:
NO and H2SO4

Solution:
An odd electron bond means there is an odd number of the electron in the overall molecule. Or we can say that the molecule has unpaired electrons.

So, in NO, the valence electrons in nitrogen are 5, and valence electrons in oxygen are 6. So, by adding we get, 6+5=11

In sulfuric acid (H2SO4), each oxygen has a full octet (eight valence electrons), whereas sulfur has an expanded octet (twelve valence electrons).

(A) BCl3→ Even Electron molecule SF6→ Expanded octet molecule

(B) NO→ Odd Electron molecule H2SO4→ Expanded octet.

(C) SF6→ Even Electron molecule H2SO4→ Expanded octet.

(D) BCl3→ Even Electron molecule NO→ Odd Electron molecule

Topic: Chemistry, Chemical Bonding and Molecular Structure, JEE Main, JEE Main 2022 (29 Jul Shift 1)
Which of the following pairs are correctly matched?

Options:
A Only I
B $\mid$ and II
C II and III
D II and IV

The correct answer is:
II and IV

Solution:
(i) $R \mathrm{X}+\mathrm{Ag}^{+} \mathrm{OH}^{-}$(moist) $\stackrel{\Delta}{\longrightarrow} \underset{\text { alcohol }}{\mathrm{ROH}}+\mathrm{AgX}$
(ii)
(iii)
(iv) $2 R X+2 \mathrm{Na} \stackrel{\text { ether }}{\longrightarrow} \underset{\text { higher alkanes }}{R-R}+2 \mathrm{NaX}$

Topic: Chemistry, Haloalkanes and Haloarenes, JEE Main
Which of the following pairs constitutes a buffer?

Options:
A \( \mathrm{HCl} \) and \( \mathrm{KCl} \)
B \( \mathrm{HNO}_{2} \) and \( \mathrm{NaNO}_{2} \)
C \( \mathrm{NaOH} \) and \( \mathrm{NaCl} \)
D \( \mathrm{HNO}_{3} \) and \( \mathrm{NH}_{4} \mathrm{NO}_{3} \)

The correct answer is:
\( \mathrm{HNO}_{2} \) and \( \mathrm{NaNO}_{2} \)

Solution:
HNO2 and NaNO2 are examples of acidic buffer.

Acidic buffer is a mixture of weak acid with the salt of weak acid with strong base.

Here HNO2 is a weak acid and NaNO2 is salt of weak acid with strong base.

Hence, HNO2 & NaNO2 is an acidic buffer.

Topic: Chemistry, Ionic Equilibrium, JEE Main
Which of the following pairs constitutes a buffer?

Options:
A $\mathrm{HCl}$ and $\mathrm{KCl}$
B $\mathrm{HNO}_2$ and $\mathrm{NaNO}_2$
C $\mathrm{NaOH}$ and $\mathrm{NaCl}$
D $\mathrm{HNO}_3$ and $\mathrm{NH}_4 \mathrm{NO}_3$

The correct answer is:
$\mathrm{HNO}_2$ and $\mathrm{NaNO}_2$

Solution:
The pair $\mathrm{HNO}_2$ and $\mathrm{NaNO}_2$ constitutes a buffer because $\mathrm{HNO}_2$ is a weak acid and $\mathrm{NaNO}_2$ is a salt of a weak acid $\left(\mathrm{HNO}_2\right)$ with a strong base $(\mathrm{NaOH})$. Hence, it is an example of an acidic buffer solution.
Caution
Solutions of a weak acid and its conjugate base or weak base and its conjugate acid are able to maintain $\mathrm{pH}$ forming buffer solutions.

Topic: Chemistry, Ionic Equilibrium, NEET, NEET 2006
Which of the following pairs give positive Tollen's test?

Options:
A Glucose,sucrose
B Glucose, fructose
C Hexanal,acetophenone
D Fructose,sucrose

The correct answer is:
Glucose, fructose

Solution:
Aldehydes and $\alpha$-hydroxy ketones give positive Tollen's test. Glucose being a polyhydroxy aldehyde and fructose an $\alpha$-hydroxy ketone give positive Tollen's test.

Topic: Chemistry, Aldehydes and Ketones, JEE Main
Which of the following pairs has both members from the same period of periodic table:

Options:
A $\mathrm{Na}, \mathrm{Ca}$
B $\mathrm{Na}, \mathrm{Cl}$
C $\mathrm{Ca}, \mathrm{Cl}$
D $\mathrm{Cl}, \mathrm{Br}$

The correct answer is:
$\mathrm{Na}, \mathrm{Cl}$

Solution:
$_{11} \mathrm{Na} \Rightarrow 2,8,1 ;{ }_{17} \mathrm{Cl} \Rightarrow 2,8,7$
These have same number of shells. Hence, they are the elements of the same period.

Topic: Chemistry, Classification of Elements and Periodicity in Properties, JEE Main
Which of the following pairs has the same size?

Options:
A $\mathrm{Fe}^{2+}, \mathrm{Ni}^{2+}$
B $\mathrm{Zr}^{4+}, \mathrm{Ti}^{4+}$
C $\mathrm{Zr}^{4+}, \mathrm{Hf}^{4+}$
D $\mathrm{Zn}^{2+}, \mathrm{Hf}^{4+}$

The correct answer is:
$\mathrm{Zr}^{4+}, \mathrm{Hf}^{4+}$

Solution:
In general, the atomic and ionic radii increases on moving down a group. But the elements of second transition series (eg, $\mathrm{Zr}, \mathrm{Nb}$, Mo etc) have the almost same radii as the elements of third transition series (eg, Hf, Ta, W etc). This is because of lanthanide contraction ie, imperfect shielding of one $4 \mathrm{f}$-electron by another.

Topic: Chemistry, Structure of Atom, JEE Main
Which of the following pairs has the same size?

Options:
A $\mathrm{Fe}^{2+}, \mathrm{Ni}^{2+}$
B $\mathrm{Zr}^{4+}, \mathrm{Ti}^{4+}$
C $\mathrm{Zr}^{4+}, \mathrm{Hf}^{4+}$
D $\mathrm{Zn}^{2+}, \mathrm{Hf}^{4+}$

The correct answer is:
$\mathrm{Zr}^{4+}, \mathrm{Hf}^{4+}$

Solution:
The similarity in the size of ions of the elements belonging to the same group of the second and third transition series is due to the effect of lanthanoid contraction. Thus, $\mathrm{Zr}^{4+}$ and $\mathrm{Hf}^{4+}$ has same size.

Topic: Chemistry, d and f Block Elements, JEE Main
Which of the following pairs has the same size?

Options:
A Zn2+,Hf4+
B Fe2+,Cu2+
C Zr4+,Hf4+
D Zr4+,Ti4+

The correct answer is:
Zr4+,Hf4+

Solution:
Here Zr+4 (4d) and Hf+4 (5d) are having same size which is possible due to poor screening effect by inner d or f orbitals electrons due to highly diffused shape of these orbitals or lanthanide contraction in Hf .

Topic: Chemistry, d and f Block Elements, JEE Main
Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?

Options:
A Exothermic and increasing disorder
B Exothermic and decreasing disorder
C Endothermic and increasing disorder
D Endothermic and decreasing disorder

The correct answer is:
Exothermic and increasing disorder

Solution:
ΔG < 0. As per Gibbs Helmholtz equation,
ΔG = ΔH−TΔS
Thus ΔG is âve only
When ΔH = −ve (exothermic)
and ΔS = +ve (increasing disorder)
This reaction will be spontaneous at all Temperatures.

Topic: Chemistry, Thermodynamics (C), JEE Main
Which of the following pairs of a chemical reaction is certain to result in spontaneous reaction?

Options:
A Exothermic and decreasing disorder
B Endothermic and increasing disorder
C Exothermic and increasing disorder
D Endothermic and decreasing disorder

The correct answer is:
Exothermic and increasing disorder

Solution:
$\Delta G=\Delta H-T \Delta S$
for spontoneous process $\Delta G$ should be negative in option (3) $\Delta H=-v e$ and $\Delta S=+v e$ than
$\Delta G=(-v e)-T(+v e)=-v e$

Topic: Chemistry, Thermodynamics (C), JEE Main
Which of the following pairs of compounds are enantiomers

Options:
A

B

C

D

The correct answer is:

Solution:
Structures are mirror images of each other which are non super impossible so they are enantiomers.

Topic: Chemistry, General Organic Chemistry, JEE Main
Which of the following pairs of compounds are more stable?

Options:
A K2NiCl6,Pt(CN)42-
B NiCl4,PtCl4
C Ni(CN)42-,K2PtCl6
D PtCl2,NiCl2

The correct answer is:
Ni(CN)42-,K2PtCl6

Solution:
By comparing the value of ionization energies the thermodynamic stability of transition metal compound can be compared. Ionization value shows that NiII compound are more stable then Pt(II) compound while Pt(IV) compound are relatively more stable than Ni(IV) .

Topic: Chemistry, Coordination Compounds, JEE Main
Which of the following pairs of compounds are positional isomers?

Options:
A
B
C
D

The correct answer is:

Solution:
Positional isomers are constitutional isomers that have the same carbon skeleton and the same functional groups but differ from each other in the location of the functional groups in the carbon chain.

Topic: Chemistry, General Organic Chemistry, JEE Main, JEE Main 2015 (11 Apr Online)
Which of the following pairs of gases is mainly responsible for green house effect?

Options:
A Ozone and Ammonia
B Oxygen and Nitrogen
C Nitrogen and Sulphur dioxide
D Carbon dioxide and Methane

The correct answer is:
Carbon dioxide and Methane

Solution:
Greenhouse effect and global warming is a natural phenomenon responsible for heating of earth’s surface and atmosphere due to increase in the concentration of CO2 (64.3%), methane gas (17%) and N2O (6%) (greenhouse gases).

The surface of the earth re-emits heat in the form of infrared radiation but part of this does not reflect back due to greenhouse gases leads to the heating of the earth's atmosphere.

Hence, the right option is 4 carbon dioxide and methane.

Topic: Biology, Environmental Issues, NEET, NEET 2019 (All India)
Which of the following pairs of ions in iso-electronic and iso-structural?

Options:
A $\mathrm{CO}_{3}^{2-}, \mathrm{NO}_{3}^{-}$
B $\mathrm{SO}_{3}^{2-}, \mathrm{NO}_{3}^{-}$
C $\mathrm{ClO}_{3}^{-}, \mathrm{CO}_{3}^{2-}$
D $\mathrm{SO}_{3}^{2-}, \mathrm{CO}_{3}^{2-}$

The correct answer is:
$\mathrm{CO}_{3}^{2-}, \mathrm{NO}_{3}^{-}$

Solution:
In $\mathrm{CO}_{3}^{2-}$, total number of electrons $=32$
In $\mathrm{NO}_{3}^{-}$, total number of electrons $=32$
In $\mathrm{SO}_{3}^{2-}$, total number of electrons $=42$
So, the option (a) is correct.

Topic: Chemistry, Chemical Bonding and Molecular Structure, JEE Main
Which of the following pairs of iron are isoelectronic and isostructural?

Options:
A CO32-,Â SO32-
B ClO3-, CO32-
C SO32-,Â NO3-
D ClO3-, SO32-

The correct answer is:
ClO3-, SO32-

Solution:
Isoelectronic (same no of electrons)
ClO3- & SO32-â17+24+1=42
and 16+24+2=42
Isostructural (same type of hybridization)
ClO3-âH=127+1=4 sp3
SO32-âH=126+2=4 (sp3)

Topic: Chemistry, Structure of Atom, JEE Main
Which of the following pairs of organs includes only the endocrine glands?

Options:
A Adrenal and Ovary
B Parathyroid and Adrenal
C Pancreas and Parathyroid
D Thymus and Testes

The correct answer is:
Parathyroid and Adrenal

Solution:
Testes, Ovaries and Pancreas have both exocrine and endocrine functions; but Parathyroid and Adrenals have only endocrine function.

Topic: Biology, Chemical Coordination and Integration, NEET, NEET 2008 (Mains)
Which of the following pairs represents isobars?

Options:
A ${ }^3 \mathrm{He}_2$ and ${ }^4 \mathrm{He}_2$
B ${ }^{24} \mathrm{Mg}_{12}$ and ${ }^{25} \mathrm{Mg}_{12}$
C ${ }^{40} \mathrm{~K}_{19}$ and ${ }^{40} \mathrm{Ca}_{20}$
D ${ }^{40} \mathrm{~K}_{19}$ and ${ }^{39} \mathrm{~K}_{19}$

The correct answer is:
${ }^{40} \mathrm{~K}_{19}$ and ${ }^{40} \mathrm{Ca}_{20}$

Solution:
${ }^{40} \mathrm{~K}_{19}$ and ${ }^{40} \mathrm{Ca}_{20}$
Atoms of different elements that have the same mass number but different atomic number are called isobars.

Topic: Physics, Atomic Physics, JEE Main
Which of the following pairs represents linkage isomers ?

Options:
A
$\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]\left[\mathrm{Pt} \mathrm{Cl}_4\right]$ and $\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4\right]\left[\mathrm{CuCl}_4\right]$

B
$\left[\mathrm{Pd}\left(\mathrm{PPh}_3\right)_2(\mathrm{NCS})_2\right]$ and $\left[\mathrm{Pd}\left(\mathrm{PPh}_3\right)_2(\mathrm{SCN})_2\right]$

C
$\left[\mathrm{CO}\left(\mathrm{NH}_3\right)_5 \mathrm{NO}_3\right] \mathrm{SO}_4$ and $\left[\mathrm{CO}\left(\mathrm{NH}_3\right)_5 \mathrm{SO}_4\right] \mathrm{NO}_3$

D
$\left[\mathrm{PtCl}_2\left(\mathrm{NH}_3\right)_4\right] \mathrm{Br}$ and $\left[\mathrm{PtBr}_2\left(\mathrm{NH}_3\right)_4\right] \mathrm{Cl}_2$

The correct answer is:
$\left[\mathrm{Pd}\left(\mathrm{PPh}_3\right)_2(\mathrm{NCS})_2\right]$ and $\left[\mathrm{Pd}\left(\mathrm{PPh}_3\right)_2(\mathrm{SCN})_2\right]$

Solution:
NCS is ambidentate ligand and it can be linked through $N$ (or) S

Topic: Chemistry, Coordination Compounds, JEE Main, JEE Main 2009
Which of the following paramagnetic ions would exhibit a magnetic moment (spin only) of the order of $5 \mathrm{BM}$ ?
(At. Nos. $\mathrm{Mn}=25, \mathrm{Cr}=24, \mathrm{~V}=23, \mathrm{Ti}=22$ )

Options:
A
$\mathrm{Mn}^{2+}$

B
$\mathrm{Ti}^{2+}$

C
$\mathrm{V}^{2+}$

D
$\mathrm{Cr}^{2+}$

The correct answer is:
$\mathrm{Cr}^{2+}$

Solution:
Hence $\mathrm{Cr}^{2+}$ has magnetic moment of the order of 5 B.M.

Topic: Chemistry, Structure of Atom, JEE Main, JEE Main 2012 (19 May Online)
Which of the following parameters can define the thermodynamic state of a system?

Options:
A Work
B Temperature
C Gravity
D Velocity

The correct answer is:
Temperature

Solution:
Thermodynamic state of a system is a set of values that specifies the condition of a system at a specific time. It can be defined by specifying certain state variables. Examples of state variables include temperature, volume, pressure, mass, etc.

Temperature is a physical quantity that measures the hotness or coldness of a body. Its SI unit is kelvin.

Topic: Physics, Thermodynamics, JEE Main
Which of the following parameters does not characterize the thermodynamic state of matter?

Options:
A
temperature

B
Pressure

C
Work

D
Volume

The correct answer is:
Work

Solution:
No Solution Available

Topic: Physics, Thermodynamics, JEE Main, JEE Main 2003
Which of the following particles has more electrons than neutrons

Options:
A $\mathrm{C}$
B $\mathrm{F}^{-}$
C $\mathrm{O}^{-2}$
D $\mathrm{Al}^{+3}$

The correct answer is:
$\mathrm{O}^{-2}$

Solution:
have more electrons than neutron $\mathrm{p}=8, \mathrm{e}=10, \mathrm{n}=8$.

Topic: Chemistry, Structure of Atom, JEE Main
Which of the following pentoses will be optically active

Options:
A All
B II and III
C |
D ||

The correct answer is:
All

Solution:
All are optically active

Topic: Chemistry, Biomolecules, JEE Main
Which of the following phosphorus oxyacids can act as a reducing agent?

Options:
A $\mathrm{H}_{3} \mathrm{PO}_{3}$
B $\mathrm{H}_{3} \mathrm{PO}_{4}$
C $\mathrm{H}_{2} \mathrm{P}_{2} \mathrm{O}_{6}$
D $\mathrm{H}_{4} \mathrm{P}_{2} \mathrm{O}_{7}$

The correct answer is:
$\mathrm{H}_{3} \mathrm{PO}_{3}$

Solution:
Oxyacid of phosphorus which contains $\mathrm{P}-\mathrm{H}$ bonds can act as a reducing agent. $\mathrm{H}_{3} \mathrm{PO}_{3}$ contains one $\mathrm{P}-\mathrm{H}$ bond and hence acts as a reducing agent.

Topic: Chemistry, Redox Reactions, JEE Main
Which of the following physical quantities has neither dimensions nor unit?

Options:
A Angle
B Luminous intensity
C Coefficient of friction
D Current

The correct answer is:
Coefficient of friction

Solution:
Unit less physical quantities are always dimensionless. For example, refractive index and relative density. These quantities are the ratio of same physical quantities.

A dimensionless physical quantity may have a unit. For example, plane angle and solid angle. The unit of plane angle is radian but it is dimensionless.

Now,

Coefficient of friction=friction forceNormal reactiom
=MLT-2MLT-2= no dimensions
Unit=NN= no unit

The coefficient of friction is the ratio of two forces. Hence, it is dimensionless. It also don't have any unit.

Topic: Physics, Units and Dimensions, JEE Main
Which of the following physical quantities has neither dimensions nor unit?

Options:
A Angle
B Luminous intensity
C Coefficient of friction
D Current

The correct answer is:
Coefficient of friction

Solution:
Coefficient of friction = Applied force Normal reactiom
=MLT-2MLT-2= no dimensions
Unit=NN= no unit

Topic: Physics, Units and Dimensions, JEE Main
Which of the following physical quantities have the same dimensions?

Options:
A Electric displacement D→ and surface charge density
B Displacement current and electric field
C Current density and surface charge density
D Electric potential and energy

The correct answer is:
Electric displacement D→ and surface charge density

Solution:
Electric displacement

D→=ϵ0E→

D=ϵ0E=ϵ0σϵ0

D=σ

And surface charge density =σ.

Thus, electric displacement D and surface charge density have same dimension.

Topic: Physics, Units and Dimensions, JEE Main, JEE Main 2022 (25 Jul Shift 1)
Which of the following plant species you would select for the production of bioethanol ?

Options:
A Jatropa
B Brassica
C ZeaMays
D Pongamia

The correct answer is:
ZeaMays

Solution:
No Solution Available

Topic: Biology, Strategies for Enhancement in Food Production, NEET, NEET 2009 (Mains)
Which of the following play significant role in depletion of ozone layer?

Options:
A Oxides of nitrogen
B Oxides of carbon
C Oxides of sulphur
D None of the above

The correct answer is:
Oxides of nitrogen

Solution:
Depletion of ozone layer is mainly due to oxides of nitrogen.

Topic: Chemistry, Environmental Chemistry, NEET
Which of the following plays an active role in the RAAS mechanism?

Options:
A A and E
B B and C
C CÂ andÂ D
D A and D

The correct answer is:
A and D

Solution:
The Renin-Angiotensin-Aldosterone System (RAAS) is a hormone system within the body that is essential for the regulation of blood pressure and fluid balance. The system is mainly comprised of the three hormones renin, angiotensin II and aldosterone. Primarily it is regulated by the rate of renal blood flow. The JG cells of the kidney and adrenal gland actively takes part in the RAAS mechanism.
A - adrenal gland
B - renal artery
C - renal vein
D - kidney
E - inferior vena cava

Topic: Biology, Excretory Products and their Elimination, NEET
Which of the following plots of radial-probability function 4πr2ψ2 is/are correct

(i)

(ii)

(iii)

(iv)

Options:
A Only i
B ii and iii
C i and iii
D all

The correct answer is:
i and iii

Solution:
(i) and (iii) are correct graph according to their orbitals 1s & 3s respectively.
Graph of 2s:
Graph of 3p:
(i) - (iv) - As all graphs for 4Ïr2Î¨2 v/s r start from origin. So it is incorrect.

Topic: Chemistry, Structure of Atom, JEE Main
Which of the following plots represent an exothermic reaction?

Options:
A
B
C
D

The correct answer is:

Solution:
For exothermic reaction.
$\because$
$K_{p} \propto \frac{1}{T}$
Thus, as $\frac{1}{T}$ increases (i.e. $T$ decreases), $K_{p}$ increases.
$\because$ $\Delta$ H for exothermic reactions is negative.

Topic: Chemistry, Chemical Equilibrium, JEE Main
Which of the following plots represent correct variation of equivalent conductance (Λ) with dilution for a strong electrolyte?

Options:
A
B
C
D

The correct answer is:

Solution:
This is because equivalent conductance of a strong electrolyte first increases with dilution and then becomes almost constant.

Topic: Chemistry, Electrochemistry, JEE Main
Which of the following points lie on the parabola $x^2=4$ ay

Options:
A $x=a t^2, y=2 a t$
B $x=2 a t, y=a t$
C $x=2 a t^2, y=a t$
D $x=2 a t, y=a t^2$

The correct answer is:
$x=2 a t, y=a t^2$

Solution:
[1]Substituting $\mathrm{x}=\mathrm{at}^2, \mathrm{y}=2$ at in given equation,
Substituting $\mathrm{x}=a t^2, \mathrm{y}=2 \mathrm{at}$ in given equation, $x^2=4 a y$
$\begin{aligned} & \Rightarrow\left(a t^2\right)^2=4 a(2 a t) \\ & \Rightarrow a^2 t^4 \neq 8 a^2 t\end{aligned}$
$\therefore x=a t^2, y=2 a t$ does not lies on parabola
$x^2=4 a y$
[2]Substituting $\mathrm{x}=2 \mathrm{at}, \mathrm{y}=$ at in given equation, $x^2=4 a y$
$x^2=4 a y$
$\Rightarrow(2 a t)^2=4 a(a t)$
$\Rightarrow 4 a^2 t^2 \pm 4 a^2 t$
$\therefore \mathrm{x}=2 \mathrm{at}, \mathrm{y}=$ at does not lies on parabola $\mathrm{x}^2=4 a y$
[3]Substituting $\mathrm{x}=2$ at, $\mathrm{y}=2$ at in given equation,
$x^2=4 a y$
$\Rightarrow(2 a t)^2=4 a(2 a t)$
$\Rightarrow 4 a^2 t^2 \neq 8 a^2 t$
$\therefore x=2 a t, y=2 a t$ does not lies on parabola
$x^2=4 a y$
[4]Substituting $\mathrm{x}=2 \mathrm{at}, \mathrm{y}=a \mathrm{at}^2$ in given equation,
$x^2=4 a y$
$\Rightarrow(2 a t)^2=4 a\left(a t^2\right)$
$\Rightarrow 4 a^2 t^2=4 a^2 t^2$
$\therefore x=2 a t, y=a t^2$ lies on parabola $x^2=4 a y$

Topic: Mathematics, Parabola, JEE Main
Which of the following points lies on the locus of the foot of perpendicular drawn upon any tangent to the ellipse, x24+y22=1 from any of its foci?

Options:
A (-2,3)
B (-1,2)
C (-1,3)
D (1,2)

The correct answer is:
(-1,3)

Solution:
Foot of perpendicular from focus upon any tangent lies on auxiliary circle

So equation of locus is: x2+y2=4

Now verify option

Topic: Mathematics, Ellipse, JEE Main, JEE Main 2020 (06 Sep Shift 1)
Which of the following points lies on the tangent to the curve x4ey+2y+1=3 at the point (1,0)?

Options:
A (2, 2)
B (2, 6)
C (–2, 6)
D (-2, 4)

The correct answer is:
(–2, 6)

Solution:
eyy'x4+4x3ey+2y'12y+1=0

at (1,0)
y'+4+y'=0 ⇒ y'=-2
equation of tangent at (1,0) is 2 x+y-2=0
so option (3) is correct

Topic: Mathematics, Application of Derivatives, JEE Main, JEE Main 2020 (05 Sep Shift 2)
Which of the following poisons is a narcotic?

Options:
A Opium
B Liquor
C Hashish
D Cannabis

The correct answer is:
Opium

Solution:
Opium:
- It is a narcotic and highly addictive drug.
- It is collected from dried latex from the opium poppy.
- Heroin is manufactured from the alkaloids morphine, which is contained in opium.
- Its alkaloid and byproducts, known as opiates, are widely known for causing respiratory and central nervous system depression, which can lead to death when taken in excess.
- It mainly comes from Pakistan, Afghanistan, Mexico, Myanmar, India, Laos, Colombia, China, and Australia.
Thus, opium poisons are a narcotic.

Topic: Chemistry, Chemistry in Everyday Life, JEE Main