datavorous/entrance-exam-dataset huggingface dataset:
Two features present in meiosis but absent in mitosis are

Options:
A Pairing of non-homologous chromosomes
B Pairing of homologous chromosomes and recombination between them
C Replication of chromosome
D All of these

The correct answer is:
Pairing of homologous chromosomes and recombination between them

Solution:
Homologous chromosomes are made up of chromosome pairs of approximately the same length, centromere position, and staining pattern, for genes with the same corresponding loci. One homologous chromosome is inherited from the organism's mother; the other is inherited from the organism's father. They have a tendency to pair with each other during meiosis and undergoes crossing over to produce new genetic recombinations.

Topic: Biology, Cell Cycle and Cell Division, NEET
Two fixed frictionless inclined planes making an angle 30o and 60o with the vertical are shown in figure two blocks A and B are placed on the two planes. What is the relative acceleration of A with respect to B?

Options:
A Zero
B 4.9 m s-2 in the vertical direction
C 4.9 m s-2 in horizontal direction
D 9.8 m s-2 in the vertical direction

The correct answer is:
4.9 m s-2 in the vertical direction

Solution:
a→A=gsin⁡60ocos⁡60i^
=g34i^-3g4j^
a→B=gsin⁡30cos⁡30i^-gsin2⁡j^
=g34i^-gj^4
a→AB= a→AB= a→A-a→B
=-3g4j^+g4j^
=-29j^
a→AB=-4.9j^

Topic: Physics, Rotational Motion, NEET
Two flasks A and B of equal volume containing equal masses of H2 and CH4 gases are at 100 K and 200 K temperature, respectively. Which of the following is true about the total KE (kinetic energy)?

Options:
A Total KE of H2 is four times that of CH4
B Total KE of CH4 is four times that of H2
C Total KE of H2 is two times that of CH4
D Total KE of CH4 is two times that of H2

The correct answer is:
Total KE of H2 is four times that of CH4

Solution:
Total KE =KE- (per mole) Ã Moles of molecules
Total KEA=32RTAnA
nA=m2
nB=m16
So nAnB=8
So Total KEATotal KEB=TANATBNB=12Ã8=4 .

Topic: Chemistry, States of Matter, NEET
Two friends are eating together on a dining table. One of them suddenly starts coughing while swallowing some food. This coughing would have been due to improper movement of

Options:
A diaphragm
B neck
C tongue
D epiglottis

The correct answer is:
epiglottis

Solution:
The epiglottis is a flap that is made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. It prevents the entry of food into the larynx, and directs it to the oesophagus. Due to improper movement of epiglottis, one may suddenly start coughing while swallowing some food.

Topic: Biology, Breathing and Exchange of Gases, NEET, NEET 2011 (Screening)
Two friends are eating together on a dining table. One of them suddenly starts coughing while swallowing some food. This coughing would have been due to improper movement of

Options:
A Epiglottis
B Diaphragm
C Neck
D Tongue

The correct answer is:
Epiglottis

Solution:
The coughing would have been due to improper movement of epiglottis.

Topic: Biology, Digestion and Absorption, NEET
Two gases A and B having the same temperature 'T', same pressure 'P' and same volume 'V' are mixed. If the temperature of mixture is unchanged and the volume occupied by it is 'V/2', then the pressure of the mixture will be

Options:
A P/2
B P
C 2P
D 4P

The correct answer is:
4P

Solution:
Since temperature, pressure and volume are same for both the gases implies that their number of moles, on mixing becomes double. Keeping the temperature same and reducing the volume to half, pressure becomes 4 times.
P1V1=n1RT
P2.V12=2n,RT
That is P2=4P1

Topic: Chemistry, States of Matter, NEET
Two gases $A$ and $B$ having the same volume diffuse through a porous partition in 20 and 10 seconds respectively. The molecular mass of $A$ is $49 \mathrm{u}$. Molecular mass of $B$ will be

Options:
A $12.25 \mathrm{u}$
B $6.50 \mathrm{u}$
C $25.00 \mathrm{u}$
D $50.00 \mathrm{u}$

The correct answer is:
$12.25 \mathrm{u}$

Solution:
$$
\frac{r_A}{r_B}=\sqrt{\frac{M_B}{M_A}}
$$
or $\frac{V_A}{t_A} \times \frac{t_B}{V_B}=\sqrt{\frac{M_B}{M_A}}$
or $\quad \frac{10}{20}=\sqrt{\frac{M_B}{49}}$
or $\quad \frac{1}{4}=\frac{M_B}{49}$
$\therefore \quad M_B=\frac{49}{4}=12.25 \mathrm{u}$.

Topic: Chemistry, States of Matter, NEET, NEET 2011 (Screening)
Two genes $\mathrm{R}$ and $\mathrm{Y}$ are located very close on the chromosomal linkage map of maize plant. When RRYY and rryy genotypes ore hybridized, the $\mathrm{F}_2$ segregation will show:

Options:
A segregation in the expected $9: 3: 3$ : 1 ratio
B segregation in 3:1 ratio
C higher number of the parental types
D higher number of the recombinant types.

The correct answer is:
higher number of the parental types

Solution:
When the linked genes are situated quiteclose, the chances of crossing over arehighly reduced. Due to this, large number of parental gametes are formed and only few recombinant gametes are formed. This results in higher number of parental typesin $\mathrm{F}_2$ generation as compared to recombinants.

Topic: Biology, Principles of Inheritance and Variation, NEET, NEET 2007
Two glass bulbs A and B are connected by a very small tube having a stop-cock. Bulb A has a volume of 100 cm3 and contained the gas; while bulb B was empty. On opening the stop-cock, the pressure fell down to 40%. The volume of the bulb B must be

Options:
A 75Â cm3
B 125Â cm3
C 150 cm3
D 250Â cm3

The correct answer is:
150 cm3

Solution:
P1=1 atm
P2=1 atmÃ40100=0.40 atm
V1=100 cm3
V2=?
At constant temperature, P1V1=P2V2
So V2=P1V1P2
-1 atmÃ100 cm30.40 atm
=250 cm3
Hence, the volume of bulb B= 250−100   cm 3
=150  cm 3

Topic: Chemistry, States of Matter, NEET
Two half cells have reduction potentials â0.76 V and â 0.13 V respectively. A galvanic cell is made from these two half cells. Which of the following statements is correct?

Options:
A Electrode of half-cell potential â0.76 V acts as cathode
B Electrode of half-cell potential â0.76 V acts as anode
C Electrode of half-cell potential â0.13 V acts as anode
D Electrode of half-cell potential â 0.76 V acts as positive electrode and â0.13 V as negative electrode

The correct answer is:
Electrode of half-cell potential â0.76 V acts as anode

Solution:
According to the electrochemical series, the electrode with high reduction potential will act as a cathode, and the electrode with more negative reduction potential acts as the anode.

Topic: Chemistry, Electrochemistry, NEET
Two heat engines are operating in such a way that the heat rejected by the first engine is used as the heat input of the second. If both the engines are 40% efficient, then the overall efficiency of the system is

Options:
A 0.64
B 0.8
C 0.5
D 0.9

The correct answer is:
0.64

Solution:
Let say Qin=Q is the heat input to the first engine.

Since the engine is 40% efficient,

W=0.4Q and Qout=0.6Q

The output from the second engine is the input for the first. This means,

Q'in=0.6Qin=0.6Q

W'=0.4Ã0.6Q=0.24Q and Q'out=0.6Ã0.6Q=0.36Q

Overall efficiency Î·=Qin-Q'outQin=1-0.36=0.64

Topic: Physics, Thermodynamics, NEET
Two heaters A and B have power rating of 1 kW and 2 kW , respectively. Those two are first connected in series and then in parallel to a fixed power source. The ratio of power outputs for these two cases is:

Options:
A 2:9
B 1:2
C 2:3
D 1:1

The correct answer is:
2:9

Solution:
$\begin{aligned}
& \therefore \text { Power Consumed }=P=\frac{V^2}{R} \\
& \frac{P_A}{P_B}=\frac{R_B}{R_A} \\
& R_A=2 R_B
\end{aligned}$
For Series Combination
$P_S=\frac{V^2}{3 R_B}$
For Parallel Combination
$\begin{aligned}
& P_P=\frac{3 V^2}{2 R_B} \\
& \frac{P_S}{P_P}=\frac{2}{9}
\end{aligned}$

Topic: Physics, Motion In One Dimension, NEET, NEET 2024
Two heating coils of resistances 10 Î© and 20 Î© are connected in parallel and are connected to a battery of emf 12 V and internal resistance 1 Î©. The power consumed by them are in the ratio

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

The correct answer is:
2:1

Solution:
Power, P=i2R=V2R
P1=V2R1
P2=V2R2
â´ P1P2=R2R1=2010=21 or 2:1

Topic: Physics, Current Electricity, NEET
Two hollow conducting spheres of radii R1 and R2 R1≫R2 have equal charges. The potential would be:

Options:
A more on smaller sphere
B equal on both the spheres
C dependent on the material property of the sphere
D more on bigger sphere

The correct answer is:
more on smaller sphere

Solution:
Potential at the surface of the spheres will be given by, V=kQR. As charge on both the spheres is equal, therefore, smaller sphere will have higher potential.

Topic: Physics, Electrostatics, NEET, NEET 2022 (Phase 1)
Two homogeneous spheres A and B of masses m and 2m having radii 2a and a respectively are placed in touch. The distance of centre of mass from first sphere is

Options:
A a
B 2a
C 3a
D None of these

The correct answer is:
2a

Solution:
We assume that origin is situated at the O1
∴ x1=0,m1=m,
x2=3a,m2=2m
∴ xCM=m1x1+m2x2m1+m2
=m×0+2m×3am+2m
=6ma3m=2a

Topic: Physics, Center of Mass Momentum and Collision, NEET
Two homogeneous spheres A and B of masses m and 2m having radii 2a and a respectively are placed in touch. The distance of the centre of mass from the first sphere is

Options:
A a
B 2a
C 3a
D none of these

The correct answer is:
2a

Solution:
We assume that origin is situated at O1.

∴x1=0, m1=m

x2=3a, m2=2m
∴ xcm=m1x1+m2x2m1+m2
=m×0+2m×3am+2m
= 6ma 3m = 2a

Topic: Physics, Center of Mass Momentum and Collision, NEET
Two homogeneous spheres A and B of masses m and 2m having radii 2a and a, respectively, are placed in touch. The distance of the centre of mass of the system from the centre of sphere A is

Options:
A a
B 2a
C 3a
D None of these

The correct answer is:
2a

Solution:
We assume that origin is situated at the O1 .
∴x1=0 ,
m1=m
x2=3a ,
m2=2m
∴xcm=m1x1+m2x2m1+m2
=m×0+2m×3am+2m
=6ma3m=2a

Topic: Physics, Center of Mass Momentum and Collision, NEET
Two homologous chromosomes are depicted in the diagram given below. Crossing over occurs between chromatid 2 and chromatid 3 at the point as depicted.

The gametes produced as a result of this crossing over will be

Options:
A Ab and aB
B AB and ab
C Ab, AB, ab and aB
D Ab, aB and ab

The correct answer is:
Ab, AB, ab and aB

Solution:
Crossing over occurs between non-sister chromatids of homologous chromosomes during the pachytene phase of meiosis I. In this example, after crossing over, chromosome number 1 will have one chromatid with Ab and another chromatid with AB. Chromosome number 2 will have one chromatid with ab and another chromatid with aB. In anaphase 1, one of these chromosomes will go in one cell and the other will go in another cell. Then in anaphase 2, the centromere of these chromosomes will split leading to the formation of four cells one with Ab, the other with AB, the third with ab and the fourth with aB.

Topic: Biology, Cell Cycle and Cell Division, NEET
Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is

Options:
A $0.75 \mathrm{~A}$
B zero
C $0.25 \mathrm{~A}$
D $0.5 \mathrm{~A}$

The correct answer is:
$0.5 \mathrm{~A}$

Solution:
Here in circuit $D_1$ is forward bias and $D_2$ is reverse bias. Current will flow only in diode $D_1$

The current supplied by the battery
$i=\frac{5}{10}=0.5 \mathrm{~A}$

Topic: Physics, Semiconductors, NEET, NEET 2012 (Screening)
Two ideal gas thermometers A and B use oxygen and hydrogen respectively. The following observations are made :
What is the absolute temperature of normal melting point of sulphur as read by thermometers A and B ?

Options:
A 663.4K
B 265.11K
C 441.6K
D 392.69K

The correct answer is:
392.69K

Solution:
Correct Option is : (D)
392.69K

Topic: Chemistry, Thermal Properties of Matter, NEET
Two identical ball bearings in contact with each other and resting on a frictionless table are hit head-on by another ball bearing of the same mass moving initially with a speed V. If the collision is elastic, which of the following (Fig. 5.14) is a possible result after collision ?

Options:
A

B

C

D None of these

The correct answer is:

Solution:
Correct Option is : (B)

Topic: Chemistry, Work Power Energy, NEET
Two identical balls A and B are released from the position shown in the figure. They collide elastically on the horizontal portion. The ratio of heights attained by A and B after collision is (neglect friction)

Options:
A 1 : 4

B 2 : 1

C 4 : 13

D 2 : 5

The correct answer is:
4 : 13

Solution:
As the mass of the two balls are equal they exchange their velocities on colliding elastically. They also exchange their kinetic energies on collision.
Therefore after collision particle A reaches the maximum height HA=h
Speed of the ball B when it reaches back to the initial position
12mv2=mg4h-mgh=3mgh
⇒v=6gh
The height reached by the particle B (from the highest point on the incline)
H=v2sin260°2g=9h4 ;
total height HB=h+9h4=13h4
Ratio HAHB=413

Topic: Physics, Center of Mass Momentum and Collision, NEET
Two identical balls A and B, each of mass 0.1 kg, are attached to two identical massless springs. The spring-mass system is constrained to move inside a rigid smooth pipe of bent in the form of a circle, as shown in the figure. The pipe is fixed in a horizontal plane. The centres of the balls can move in a circle of radius 0.06 m. Each spring has a natural length of 0.06Ï m and force constant 0.1 N m-1. Initially, both the balls are displaced by an angle Î¸=Ï6 rad, with respect to the diameter PQ of the circle, and released from rest. The frequency of oscillation of the ball B is

Options:
A π Hz
B 1Ï Hz
C 2π Hz
D 12π Hz

The correct answer is:
1Ï Hz

Solution:
As the two masses are connected by two springs, this problem is equivalent to the oscillation of a reduced mass mr, of a spring of effective spring constant Keff.
T=2ÏmrKeff
Hence, mr=m1m2m1+m2=m2, Keff=K1+K2=2K
â´ n=12ÏKeffmr=12Ï2KmÃ2=1ÏKm=1Ï0.10.1=1Ï Hz

Topic: Physics, Oscillations, NEET
Two identical balls A and B having velocities of 0.5 m s-1 and -0.3 m s-1, respectively, collide elastically in one dimension. The velocities of B and A after the collision, respectively, will be

Options:
A -0.5 m s-1 and 0.3 m s-1
B 0.5 m s-1 and -0.3 m s-1
C -0.3 m s-1 and 0.5 m s-1
D 0.3 m s-1 and 0.5 m s-1

The correct answer is:
0.5 m s-1 and -0.3 m s-1

Solution:
They will exchange their velocities, so,

vB=0.5 m s-1 and vA=-0.3 m s-1.

Topic: Physics, Center of Mass Momentum and Collision, NEET, NEET 2016 (Phase 2)
Two identical billiard balls strike a rigid wall with the same speed but at different angles, and get reflected without any change in speed, as shown in Fig. 4.6. What is the ratio of the magnitudes of impulses imparted to the balls by the wall ?

Options:
A 1
B 2
C 1.5
D 1.2

The correct answer is:
1.2

Solution:
Correct Option is : (D)
1.2

Topic: Chemistry, Laws of Motion, NEET
Two identical blocks A and B, each of mass m resting on a smooth floor, are connected by a light spring of natural length L and the spring constant k, with the spring at its natural length. A third identical block at C (mass m) moving with a speed (v) along the line joining A and B collides with A. The maximum compression in the spring is proportional to

Options:
A vm2k
B mv2k
C mvk
D mv2k

The correct answer is:
vm2k

Solution:
When block (C) strikes the block (A), then it begins to oscillate, whose time period
T=2πm2k
Compression x=vT=v×2πm2k
∴ x∝vm2k

Topic: Physics, Oscillations, NEET
Two identical blocks of mass m are suspended from a beam balance whose scale pans differ in vertical height by hâªR, If R and Ï are the radius and density of the earth, then the error in weighing is

Options:
A 23πρR3Gm
B 83πρGmh
C 83πρR3Gm
D 43πρGm2h

The correct answer is:
83πρGmh

Solution:
As with height g varies as
and in accord with the figure h1>h2 so W1 will be lesser than W2 and
W2-W1=mg2-mg1=2mgh1R-h2R
or W2-W1=2mGMR2hR
as g=GMR2 and h1-h2=h
or W2-W1=2mhGR343ÏR3Ï
=83 ÏÏGmh as M=43ÏR3Ï

Topic: Physics, Gravitation, NEET
Two identical bodies are made of a material for which the heat capacity increases with temperature. One of these is at 100 oC, while the other one is at 0 oC. If the two bodies are brought into contact, then assuming no heat loss, the final common temperature is

Options:
A 50 oC
B >50 oC
C <50 oC but >0 oC
D 0 oC

The correct answer is:
>50 oC

Solution:
Loss of heat by the hot body = gain of heat by the cold body.

Since, the heat capacity increases with temperature, the hotter body will lose more energy when its temperature falls down from 100 oC to 50 oC compared to the energy required by the cold body to raise its temperature from 0 oC to 50 oC. Thus, the temperature will be more than 50 oC.

Topic: Physics, Thermal Properties of Matter, NEET, NEET 2016 (Phase 2)
Two identical capacitors $C_1$ and $C_2$ of equal capacitance are connected as shown in the circuit. Terminals a and $\mathrm{b}$ of the key $\mathrm{k}$ are connected to charge capacitor $\mathrm{C}_1$ using battery of emf $\mathrm{V}$ volt. Now, disconnecting a and $b$ the terminals $b$ and $c$ are connected. Due to this, what will be the percentage loss of energy?

Options:
A $75 \%$
B $0 \%$
C $50 \%$
D $25 \%$

The correct answer is:
$50 \%$

Solution:
When $\mathrm{C}_1$ is connected to voltage source, it is charged to a potential $V$ and this will be stored as a potential energy in the capacitor given by
$$
\mathrm{U}=\frac{1}{2} \mathrm{CV}^2
$$
When key is disconnected from battery and band c are connected, the charge will be transformed from the capacitor $\mathrm{C}_1$ to capacitor $\mathrm{C}_2$, then
The loss of energy due to redistribution of charge is given by
$$
\begin{aligned}
& \begin{aligned}
\Delta \mathrm{U} & =\frac{\mathrm{C}_1 \mathrm{C}_2}{2\left(\mathrm{C}_1+\mathrm{C}_2\right)}\left(\mathrm{V}_1-\mathrm{V}_2\right)^2 \\
& =\frac{\mathrm{C} \times \mathrm{C}}{2(\mathrm{C}+\mathrm{C})}(\mathrm{V}-0)^2=\frac{1}{4} \mathrm{CV}^2 \quad\left[\because \mathrm{C}_1=\mathrm{C}_2\right]
\end{aligned} \\
& \therefore \text { Percentage loss }=\frac{\Delta \mathrm{U}}{\mathrm{U}} \times 100=\frac{\frac{1}{4} \mathrm{CV}^2}{\frac{1}{2} \mathrm{CV}^2} \times 100=50 \%
\end{aligned}
$$

Topic: Physics, Capacitance, NEET, NEET 2019 (Odisha)
Two identical capacitors each of capacitance 5μF are charged to potentials 2kV and 1kV respectively. Their -ve ends are connected together. When the +ve ends are also connected together, the loss of energy of the system is

Options:
A 160 J
B Zero
C 5 J
D 1.25 J

The correct answer is:
1.25 J

Solution:
Loss of energy =12C1C2(C1+C2) V1-V22
=125Ã10-6Ã5Ã10-62000-100025+5Ã10-6
= 5Ã52Ã10=1.25 J

Topic: Physics, Electrostatics, NEET
Two identical capacitors have the same capacitance C. One of them is charged to potential V1 and the other to V2. If their like-charged plates are then connected together, then the decrease in energy of the combined system is

Options:
A 14CV12-V22
B 14CV12+V22
C 14CV1+V22
D 14CV1-V22

The correct answer is:
14CV1-V22

Solution:
ΔU=decrease in potential energy
=Ui-Uf
=12CV12+V22-122CV1+V222=14CV1-V22

Topic: Physics, Electrostatics, NEET
Two identical capacitors have the same capacitance C. One of them is charged to potential V1 and the other to V2. The negative ends of capacitors are connected together. When the positive ends are also connected, the decrease in energy of the combine system is

Options:
A C4V12-V22
B C4V12+V22
C C4V1-V22
D C4V1+V22

The correct answer is:
C4V1-V22

Solution:
Total energy of two identical capacitors before connection.
E1=12CV12+12CV22 .....(i)
When negative end of one capacitor is connected to negative end of other capacitor and positive to positive, then such type of connection is known as parallel connection.
Hence, equivalent capacitance after connection is given by,
Ceq=C+C
Ceq=2C
Common potential, V=Total chargeTotal capacitance
=Q1+Q2C+C
=CV1+CV22C
=V1+V22
∴ Total energy after connections
E2=12⋅Ceq⋅V2
=12⋅2CV1+V222
=C4V1+V22
∴ Decrease in energy =E1-E2
=12CV12+12CV22-C4V1+V22
=C42V12+2V22-V12+V22+2V1V2
=C4V12+V22-2V1V2=C4V1-V22

Topic: Physics, Electrostatics, NEET
Two identical capacitors have the same capacitance C. One of them is charged to potential V1 and the other to V2. The negative ends of capacitors are connected together. When the positive ends are also connected, the decrease in energy of the combined system is

Options:
A C4V12-V22
B C4V12+V22
C C4V1-V22
D C4V1+V22

The correct answer is:
C4V1-V22

Solution:
Total energy of two identical capacitors before connection.
E1=12CV12+12CV22 .....(i)
When negative end of one capacitor is connected to negative end of other capacitor and positive to positive, then such type of connection is known as parallel connection.
Hence, equivalent capacitance after connection is given by,
Ceq=C+C
Ceq=2C
Common potential, V=Total chargeTotal capacitance
=Q1+Q2C+C
=CV1+CV22C
=V1+V22
∴ Total energy after connections
E2=12⋅Ceq⋅V2
=12⋅2CV1+V222
=C4V1+V22
∴ Decrease in energy =E1-E2
=12CV12+12CV22-C4V1+V22
=C42V12+2V22-V12+V22+2V1V2
=C4V12+V22-2V1V2=C4V1-V22

Topic: Physics, Electrostatics, NEET
Two identical charged spheres suspended from a common point by two massless strings of lengths l, are initially at a distance d( d≪l ) apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity υ. Then υ varies as a function of the distance x between the spheres, as

Options:
A v∝x12
B v∝x
C v∝x-12
D v∝x-1

The correct answer is:
v∝x-12

Solution:
sinθ= θ=x2l, cosθ≈1
fecos⁡θ=mgsin​θ
fe=mg.x2l
kq2x2=mgx2l
kq2=mg2lx3
q∝x32
dqdt∝32 x12.dxdt
⇒x12.v=constant
v∝x-12

Topic: Physics, Electrostatics, NEET, NEET 2016 (Phase 1)
Two identical charges of value Q each are placed at (-a, 0) and (a, 0). The coordinates of the points where the net electric field is zero and maximum are respectively -

Options:
A 0, 0, 0, 0
B 0,a2, 0, 0
C 0, 0, 0,a2
D a2, 0, 0,a2

The correct answer is:
0, 0, 0,a2

Solution:
Net electric field will be zero at origin.
At any co-ordinate 0, y ENet=2Ecos2θ2
=kQya2+y232
For maximum electric field dEdy=0
Solving y=±a2

Topic: Physics, Electrostatics, NEET
Two identical conducting balls A and B have positive charges q1 andq2 respectively but q1≠q2. The balls are brought together so that they touch each other and then kept in their original positions. The force between them is

Options:
A Less than that before the balls touched
B Greater than that before the balls touched
C Same as that before the balls touched
D Zero

The correct answer is:
Greater than that before the balls touched

Solution:
Original charges on spheres A and B be q1 and q2 respectively.
Distance between the two spheres =r
Since, both the spheres are of same size, they will possess equal charges on being brought in contact.
∴ q1′=q1+q22
Similarly q2 ′=q1+q22
Therefore, new force of repulsion between spheres A and B is
F′=14πε0q1+q22q1+q22r2
=q1+q2224πε0r2
As q1+q222>q1q2
∴ F′>F

Topic: Physics, Electrostatics, NEET
Two identical conducting rods are first connected independently but simultaneously between two vessels, one containing water at 100 Â°C and the other containing ice at 0 Â°C. In the second case, the rods are connected in series and then the combination is connected between the same vessels. Let q1 and q2 be the rate of melting of ice (in g s-1) in the two cases respectively. The ratio q1q2 is

Options:
A 12
B 21
C 41
D 14

The correct answer is:
41

Solution:
Heat current, dQdt=Ldmdt
Temperature differenceThermal resistance= Ldmdt
dmdt∝ 1Thermal resistance
q∝1R
In the first case rods are in parallel and thermal resistance is R2 while in second case rods are in series and thermal resistance is 2R.
∴ q1q2= 2RR/2= 41

Topic: Physics, Thermal Properties of Matter, NEET