datavorous/entrance-exam-dataset huggingface dataset:
A maximum number of free vertebrae in humans are found in

Options:
A thoracic region.
B cervical region.
C lumbar region.
D coccygeal region.

The correct answer is:
thoracic region.

Solution:
The number of free vertebrae in different regions is as follows:
Thoracic: 12
Cervical: 7
Lumbar: 5
Coccygeal: No free vertebrae. The vertebrae fuse to form the coccyx bone.
Thus, the maximum number of free vertebrae in humans are found in thoracic region.

Topic: Biology, Locomotion and Movement, NEET
A member of the plant family which stores food in the endosperm

Options:
A Graminae
B Malvaceae
C Solanaceae
D Leguminosae

The correct answer is:
Graminae

Solution:
Graminae is a monocot family in which seeds are endospermic and food is stored in endosperm; their cotyledon is reduced and forms a shield like structure known as scutellum. In dicots, food is stored in cotyledons.

Topic: Biology, Morphology of Flowering Plants, NEET
A Mendel's law which does not have any exception is

Options:
A Law of dominance
B Law of segregation
C Law of independent assortment
D None have all exceptions.

The correct answer is:
Law of segregation

Solution:
Co-dominance and incomplete dominance are exceptions to the law of dominance. Linkage is the exception to the law of independent assortment. Law of segregation has no exceptions, which states that in a hybrid, the members of an allelic pair stay together without mixing and separate or segregate independently during gamete formation.

Topic: Biology, Principles of Inheritance and Variation, NEET
A mercury thermometer is constructed as shown in the diagram. The capillary tube has a diameter of 0.004 cm, and the bulb has a diameter of 0.250 cm. Neglecting the expansion of the glass, find the change in height of the mercury column with a temperature change of 30.0 Â°C.

Options:
A 3.55 cm
B 2.60 cm
C 4.50 cm
D 3.33 cm

The correct answer is:
3.55 cm

Solution:
For an easy-to-read thermometer, the column should rise by a few centimetres.
We use the definition of the coefficient of expansion of the glass, the volume of liquid in the capillary will be ΔV=AΔh, where A is the cross-sectional area of the capillary. Let Vi represent the volume of the bulb.
ΔV=ViγΔT
Δh=ViAγΔT=43πRbulb3πRcap2γΔT
Δh=430.125 cm30.002 cm21.82×10-4/∘C30.0∘C=3.55 cm
This is a practical thermometer. Glass expands so little as compared to mercury that only the third digit of the answer would be affected by including the expansion of the glass in our analysis.

Topic: Physics, Thermal Properties of Matter, NEET
A metal ball falls from a height of 1 m on to a steel plate and jumps upto a height of 81 cm. The coefficient of restitution of the ball and steel plate is

Options:
A 0.2
B 9
C 0.9
D 90

The correct answer is:
0.9

Solution:
e=Velocity of sepration Velocity of approach
e=h2h1 = 81 100 =0.9

Topic: Physics, Center of Mass Momentum and Collision, NEET
A metal ball hits a wall and does not rebound whereas a rubber ball of the same mass on hitting the wall rebounds with the same speed. It can be concluded that

Options:
A metal ball suffers greater change in momentum
B rubber ball suffers greater change in momentum.
C the initial momentum of metal ball is greater than the initial momentum of rubber ball.
D both suffer same change in momentum.

The correct answer is:
rubber ball suffers greater change in momentum.

Solution:
Change in momentum of metal ball is =0--mv=mv
Change in momentum of rubber ball is =mv--mv=2mv

Topic: Physics, Center of Mass Momentum and Collision, NEET
A metal ball immersed in water weighs w1 at 0°C and w2 at 50°C. The coefficient of cubical expansion of metal is less than that of water. Then

Options:
A w1>w2
B w1<w2
C w1=w2
D data is insufficient

The correct answer is:
w1<w2

Solution:
As the coefficient of cubical expansion is more for alcohol then metal.
When we increase temperature, expansion in alcohol is more and hence density decreases,
The buoyant force F=Vρwg decreases as an increase in metal volume are less but the decrease in the density of water is more.
Hence w1<w2

Topic: Physics, Thermal Properties of Matter, NEET
A metal ball of surface area 200 cm2, temperature 527 oC is surrounded by a vessel at 27 oC. If the emissivity of metal is 0.4, then the rate of loss of heat is nearly Ï=5.67Ã10-8 W m-2 K-4

Options:
A 108 W
B 168 W
C 182 W
D 192 W

The correct answer is:
182 W

Solution:
Rate of heat loss per unit time per unit area =eÏAT4-T04
=0.4Ã5.67Ã10-8Ã200Ã10-4Ã8004-3004
=5.67Ã0.4Ã2Ã10-8+2-4Ã108642-92
=5.67Ã0.8Ã10-255Ã73
=18212.04Ã10-2
=182.12 W

Topic: Physics, Thermal Properties of Matter, NEET
A metal crystallizes with a face-centered cubic lattice. The edge of the unit cell is $408 \mathrm{pm}$. The diameter of the metal atom is

Options:
A $288 \mathrm{pm}$
B $408 \mathrm{pm}$
C $144 \mathrm{pm}$
D $204 \mathrm{pm}$

The correct answer is:
$288 \mathrm{pm}$

Solution:
For fcc lattice,
$\begin{aligned}
& 4 r=\sqrt{2} a \\
& r=\frac{\sqrt{2}}{4} a=\frac{a}{2 \sqrt{2}} \\
& =\frac{408}{2 \sqrt{2}} \\
& =144 \mathrm{pm} \\
& \text {diameter } d=2 r=2 \times 144 \mathrm{pm} \\
& =288 \mathrm{pm}
\end{aligned}$

Topic: Chemistry, Solid State, NEET, NEET 2012 (Screening)
A metal cube of side 5 cm is charged with $6 \mu \mathrm{C}$. The surface charge density on the cube is

Options:
A $0.125 \times 10^{-3} \mathrm{C} \mathrm{m}^{-2}$
B $0.25 \times 10^{-3} \mathrm{C} \mathrm{m}^{-2}$
C $4 \times 10^{-3} \mathrm{C} \mathrm{m}^{-2}$
D $0.4 \times 10^{-3} \mathrm{C} \mathrm{m}^{-2}$

The correct answer is:
$0.4 \times 10^{-3} \mathrm{C} \mathrm{m}^{-2}$

Solution:
$\Rightarrow$ In metal all the charge is present on surface.
$Q=6 \mu C$
Total surface area $S=6 a^2$
$=6 \times\left(5 \times 10^{-2}\right)^2$
$=6 \times 25 \times 10^{-4}$
$=150 \times 10^{-4} \mathrm{~m}^2$
Surface charge density $\sigma=\frac{Q}{S}$
$=\frac{6 \times 10^{-6}}{150 \times 10^{-4}}$
$=0.4 \times 10^{-3} \mathrm{C} \mathrm{m}^{-2}$

Topic: Physics, Electrostatics, NEET, NEET 2024 (Re-NEET)
A metal disc of the radius 100 cm is rotated at a constant angular speed of 60 rad s-1 in a plane at right angles to an external field of magnetic induction 0.05 Wb m-2. The emf induced between the centre and a point on the rim will be

Options:
A 3 V
B 1.5 V
C 6 V
D 9 V

The correct answer is:
1.5 V

Solution:
Induced EMF =∫0RB×w×r×dr=B×w×R22
=12×0.05×60×12
=64=1.5 V

Topic: Physics, Electromagnetic Induction, NEET
A metal has a fcc lattice. The edge length of the unit cell is $404 \mathrm{pm}$. The density of the metal is $2.72 \mathrm{~g} \mathrm{~cm}^{-3}$. The molar mass of the metal is ( $N_A$ Avogadro's constant $=6.02 \times 10^{23} \mathrm{~mol}^{-1}$ )

Options:
A $40 \mathrm{~g} \mathrm{~mol}^{-1}$
B $30 \mathrm{~g} \mathrm{~mol}^{-1}$
C $27 \mathrm{~g} \mathrm{~mol}^{-1}$
D $20 \mathrm{~g} \mathrm{~mol}^{-1}$

The correct answer is:
$27 \mathrm{~g} \mathrm{~mol}^{-1}$

Solution:
Given, cell is fcc, so $Z=4$ Edge length, $a=404 \mathrm{pm}=4.04 \times 10^{-8} \mathrm{~cm}$ Density of metal, $d=2.72 \mathrm{~g} \mathrm{~cm}^{-3}$ $N_A=6.02 \times 10^{23} \mathrm{~mol}^{-1}$
Molar mass of the metal, $M=$ ?
We know that
density, $d=\frac{Z \times M}{2^3 \cdot N_A}$
$$
\begin{aligned}
\therefore M & =\frac{d \cdot a^3 \cdot N_A}{Z} \\
& =\frac{2.72 \times\left(4.04 \times 10^{-8}\right)^3 \times 6.02 \times 10^{23}}{4} \\
& =27 \mathrm{~g} \mathrm{~mol}^{-1}
\end{aligned}
$$

Topic: Chemistry, Solid State, NEET, NEET 2013 (All India)
A metal has a fcc lattice. The edge length of unit is 404pm.The density of metal is 2.72 g/cm3. The molar mass of the metal is
(NA, Avagadro's constant =6.02Ã1023)

Options:
A 30 g/mol
B 27âg/mol
C 20 g/mol
D 40 g/mol

The correct answer is:
27 g/mol

Solution:
As Ï=zÃmNAÃ(a)3
2.72=4Ãm6.02Ã1023Ã(4.04Ã10-8)3
On solving m=27 g/mol

Topic: Chemistry, Solid State, NEET
A metal is left exposed to the atmosphere for some time. It becomes coated with green basic carbonate. The metal must be

Options:
A Nickel
B Chromium
C Copper
D Zinc

The correct answer is:
Copper

Solution:
Here the metal is copper and green mass is of Cu(OH)2.CuCO3
2Cu+H2O+CO2+O2âCu(OH)2.CuCO3Green mass

Topic: Chemistry, d and f Block Elements, NEET
A metal M and its compound can give the following observable changes in a consequence of reactions

Options:
A Mg
B Pb
C Zn
D Sn

The correct answer is:
Zn

Solution:
Zn M ⟶ dil. HNO 3 Zn NO 3 2 Colourless Solution ⟶ NaOH Aq Zn OH 2 White ppt. ⟶ NaOH Excess Na 2 Zn OH 4 Soluble ⟶ H 2 S ZnS White ppt.

Topic: Chemistry, d and f Block Elements, NEET
A metal M forms water-insoluble hydroxide M(OH)2 and water-soluble sulphate. Its oxide MO is amphoteric in nature and possesses a high melting point. Then the metal M is:

Options:
A Be
B Mg
C Ca
D Sr

The correct answer is:
Be

Solution:
BeO and BeOH2 are water-insoluble. But, BeO is soluble in basic as well as acidic solution as it can react with both acid and base i.e. it is amphoteric. The explanation for its amphoteric behaviour is the partial covalent character of the Be-O bond. Also, due to small size and +2 charge on Be2+ ion, it can react with OH- from base and O2- can react with H+ from acid.

Topic: Chemistry, s Block Elements, NEET
A metal M reacts with nitrogen to form compound 'A'(M3N) . 'A' on heating at high temperature thermally decomposes to gives back 'M' . Further 'A' on reacting with H2O gives a gas 'B' . This 'B' turns CuSO4 solution blue on passing through it. Identify metal M and gas B

Options:
A Al and  NH 3
B Li and  NH 3
C Na and  NH 3
D Mg and  NH 3

The correct answer is:
Li and  NH 3

Solution:
Lithium form nitride on heating with nitrogen. Lithium nitride gives ammonia when heated with H2O . Ammonia gas form tetrammine copper complex with CuSO4 solution.
6Li+N2→2Li3N
Li3N+3H2O→3LiOH+NH3
CuSO4+4NH3→[Cu(NH3)4]SO4

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
A metal M readily forms its sulphate MSO4 which is water-soluble. It forms its oxide MO which becomes inert on heating. It forms its insoluble hydroxide M(OH)2 which is soluble in NaOH solution. Then M is

Options:
A Mg
B Ba
C Ca
D Be

The correct answer is:
Be

Solution:
The solubility of hydroxides of alkaline earth metals in water increases on moving down the group.

Topic: Chemistry, s Block Elements, NEET
A metal oxide has the formula X2O3 . It can be reduced by hydrogen to give free metal and water. 0.1596 g of metal oxide requires 6 mg of hydrogen for complete reduction. The atomic mass of metal in amu is

Options:
A 15.6
B 155.8
C 30.8
D 55.8

The correct answer is:
55.8

Solution:
X2O31mol(2a+48)+3H23mol6g→2X+3H2O
0.006 g H2 is required by 0.1596 g oxide
So 6 g H2 will be require by 159.6 g oxide
So 2a+48=159.6
a = 55.8
where, a = atomic mass of metal M.

Topic: Chemistry, Some Basic Concepts of Chemistry, NEET
A metal rod of length L and cross- sectional area A is heated through T oC. What is the force required to prevent the expansion of the rod lengthwise?
[Y = Young's modulus of the material of rod, Î±= coefficient of linear expansion]

Options:
A YAαT(1-αT)
B YAαT(1+αT)
C (1-αT)YAαT
D (1+αT)YAαT

The correct answer is:
YAαT(1+αT)

Solution:
∆L=αLT ...... (i)
Also Y=FA.L(1+αt)∆L
Or ∆L=F.L(1+αt)A.Y ........ (ii)
Equating (i) and (ii)
F.L1+αtA.Y=αLT
∴ F=AYαT(1+αt)

Topic: Physics, Mechanical Properties of Solids, NEET
A metal rod of length L and cross-sectional area A is heated through T Â°C. What is the force required to prevent the expansion of the rod lengthwise?
[Y = Young's modulus of the material of rod, Î±= coefficient of linear expansion]

Options:
A YAαT(1-αT)
B YAαT(1+αT)
C (1-αT)YAαT
D (1+αT)YAαT

The correct answer is:
YAαT(1+αT)

Solution:
∆L=αLT ...... (i)
Also Y=FA.L(1+αt)∆L
Or ∆L=F.L(1+αt)A.Y ........ (ii)
Equating (i) and (ii)
F.L1+αtA.Y=αLT
∴ F=AYαT(1+αt)

Topic: Physics, Mechanical Properties of Solids, NEET
A metal rod of resistance 20 Î© is fixed along a diameter of a conducting ring of radius 0.1 m and lies on x-y plane. There is a magnetic field Bâ =(50 T) k^. The ring rotates with an angular velocity Ï=20 rad s-1 about its axis. An external resistance of 10 Î© is connected across the centre of the ring and rim. The current through external resistance is

Options:
A 12Â A
B 13 A
C 14Â A
D zero

The correct answer is:
13 A

Solution:
Here, resistance of rod =2Î©, r=0.1 m, B=50 T, along z-axis Ï=20 rad s-1.
Potential difference between centre of the ring and the rim is
V=12BÏr2=12 Ã50Ã20Ã0.12=5 V
Current through external resistance,
i= ER+r=510+5=13 A

Topic: Physics, Electromagnetic Induction, NEET
A metal sphere is hung by a string fixed to a wall. The forces acting on the sphere are shown in figure. Which of the following statements is/are correct?

a. N→+T→+W→=0

b. T2=N2+W2

c. T=N+W

d. N=Wtan⁡θ

Options:
A a, b, c
B b, c, d
C a, b, d
D a, b, c, d

The correct answer is:
a, b, d

Solution:
As the object is in equilibrium, the net force is zero
N→+T→+W→=0
Also from the diagram, T2=N2+W2
From components, N=Wtan⁡θ

Topic: Physics, Laws of Motion, NEET
A metal sphere of radius r and specific heat S is rotated about an axis passing through its centre, at a speed of n rotations per second. It is suddenly stopped and 50 % of its energy is used in increasing its temperature. Then, the rise in temperature of the sphere is

Options:
A 2Ï2n2r25S
B π2n210r2S
C 78 πr2n2S
D 5πrn214S

The correct answer is:
2π2n2r25S

Solution:
I=25mr2, Ï=2Ïn
k=12IÏ2=12Ã25mr2Ã4Ï2n2
=45Ï2mr2n2
ÎÎ¸=ÎQmS=k2mS
=25Ï2mr2n2mS
=2Ï2r2n25S

Topic: Physics, Thermal Properties of Matter, NEET
A metal surface is illuminated by a light of given intensity and frequency to cause photoemission. If the intensity of illumination is reduced to one-fourth of its original value, then the maximum kinetic energy of the emitted photoelectrons would become

Options:
A Four times the original value
B Twice the original value
C 16th of the original value

D unchanged

The correct answer is:
unchanged

Solution:
The maximum KE of the emitted photoelectrons is independent of the intensity of the incident light but depends upon the frequency of the incident light

Topic: Physics, Dual Nature of Matter, NEET
A metal surface of work function 1.07 eV is irradiated with light of wavelength 332 nm. The retarding potential required to stop the escape of photoelectrons is

Options:
A 1.07 eV

B 2.66 eV

C 3.7 eV

D 4.81 eV

The correct answer is:
2.66 eV

Solution:
Retarding potential,
Vs=hcÎ»e-Ï0e=1240Ã10-9330Ã10-9-1.07
=3.73-1.07=2.66 V

Topic: Physics, Dual Nature of Matter, NEET
A metal wire has mass (0.4±0.002) g, radius (0.3±0.001) mm and length (5±0.02) cm. The maximum possible percentage error in the measurement of density will nearly be:

Options:
A 1.4%
B 1.2%
C 1.3%
D 1.6%

The correct answer is:
1.6%

Solution:
Density=massvolume

⇒ρ=mπr2l

Therefore, percentage error can be written as

⇒dρρ×100=dmm+2drr+dll×100=0.0020.4+20.0010.3+0.025×100≈1.6%

Topic: Physics, Mathematics in Physics, NEET, NEET 2023 (All India)
A metal wire of length L, area of cross-section A and Youngâs modulus Y is stretched by a variable force F such that F is always slightly greater than the elastic forces of resistance in the wire. If the elongation of the wire is l, then the incorrect option is

Options:
A the work done by F is YAl22L
B the work done by F is YAl2L
C the elastic potential energy stored in the wire is YAl22L
D no heat is produced during the elongation

The correct answer is:
the work done by F is YAl2L

Solution:
Work done by the stretching force is equal to the elastic potential energy stored in the wire.

Topic: Physics, Mechanical Properties of Solids, NEET
A metal wire of linear mass density of 9.8 g m-1 is stretched with a tension of 10 kg-wt between two rigid supports 1 m apart. The wire passes at its middle point between the poles of a permanent magnet and it vibrates in resonance when carrying an alternating current of frequency n. The frequency n of the alternating sources is

Options:
A 50 Hz

B 100 Hz

C 200 Hz

D 25 Hz

The correct answer is:
50 Hz

Solution:
The wire will vibrate with the same frequency as that of the source. This can be considered as an example of forced vibration.
T=10×9.8 N = 98 N
m=9.8×10-3 kg m-1
Frequency of wire
n=12LTm
=12×1989.8×10-3=50 Hz

Topic: Physics, Waves and Sound, NEET
A metallic bar of Young's modulus, $0.5 \times 10^{11} \mathrm{~N} \mathrm{~m}^{-2}$ and coefficient of linear thermal expansion $10^{-5}{ }^{\circ} \mathrm{C}^{-1}$, length 1 m and area of cross-section $10^{-3} \mathrm{~m}^2$ is heated from $0^{\circ} \mathrm{C}$ to $100^{\circ} \mathrm{C}$ without expansion or bending. The compressive force developed in it is :

Options:
A $50 \times 10^3 \mathrm{~N}$
B $100 \times 10^3 \mathrm{~N}$
C $2 \times 10^3 \mathrm{~N}$
D $5 \times 10^3 \mathrm{~N}$

The correct answer is:
$50 \times 10^3 \mathrm{~N}$

Solution:
$\begin{aligned} & \text { Thermal strain }=\text { Longitudinal strain }=\alpha \Delta T \\ & \Rightarrow \quad \text { Longitudinal strain, } \delta=10^{-5} \times 10^2=10^{-3} \\ & \Rightarrow \quad \text { Compressive stress }=\delta \times \text { Young's Modulus } \\ & =10^{-3} \times 0.5 \times 10^{11} \\ & =0.5 \times 10^8 \\ & \Rightarrow \quad \text { Compressive force }=0.5 \times 10^8 \times 10^{-3}=0.5 \times 10^5 \\ & \quad=5 \times 10^4 \times \frac{10}{10} \\ & =50 \times 10^3 \mathrm{~N}\end{aligned}$

Topic: Physics, Mechanical Properties of Solids, NEET, NEET 2024
A metallic block of density 5 gm cm-3 and having dimensions 5 cm Ã 5 cm Ã 5 cm is weighed in water. Its apparent weight will be

Options:
A 625 gf
B 256 gf
C 320 gf
D 500 gf

The correct answer is:
500 gf

Solution:
Apparent weight =V Ï-Ïg=lÃbÃh 5-1Ãg
Apparent weight=5Ã5Ã5Ã4 Dyne or
Apparent weight=4Ã5Ã5Ã5 gf
Apparent weight = 500 gf

Topic: Physics, Mechanical Properties of Fluids, NEET
A metallic carbide on reaction with water gives a colourless gas which burns readily in air and gives a precipitate with ammonical silver nitrate solution. What is the gas evolved in reaction ?

Options:
A CH4
B C2H6
C C2H4
D C2H2

The correct answer is:
C2H2

Solution:

Topic: Chemistry, p Block Elements (Group 13 & 14), NEET
A metallic ion M2+ has an electron configuration of 2, 8, 14 and its mass is 56 amu. The number of neutrons in the nucleus is

Options:
A 24
B 30
C 32
D 56

The correct answer is:
30

Solution:
As metal ion M2+ has an electron configuration of 2, 8, 14 so
The metallic atom (M) has a total number of electron =2+8+14+2=26 .
Therefore, the number of protons in the nucleus = 26.
Hence, the number of neutrons =A-Z=56-26=30 .

Topic: Chemistry, Chemical Kinetics, NEET
A metallic ring of mass m and radius l (ring being horizontal) is falling under gravity in a region having a magnetic field. If z is the vertical direction, the z-component of magnetic field is Bz= Bo(1+λ z). If R is the resistance of the ring and if the ring falls with a velocity v, find the energy lost in the resistance. If the ring has reached a constant velocity, use the conservation of energy to determine v in terms of m, B, λ and acceleration due to gravity g.

Options:
A $\frac{mgR}{9{{\left( \pi {{l}^{2}}\lambda {{B}_{o}} \right)}^{2}}}$
B $\frac{mgR}{4{{\left( \pi {{l}^{2}}\lambda {{B}_{o}} \right)}^{2}}}$
C $\frac{mgR}{16{{\left( \pi {{l}^{2}}\lambda {{B}_{o}} \right)}^{2}}}$
D $\frac{mgR}{{{\left( \pi {{l}^{2}}\lambda {{B}_{o}} \right)}^{2}}}$

The correct answer is:
$\frac{mgR}{{{\left( \pi {{l}^{2}}\lambda {{B}_{o}} \right)}^{2}}}$

Solution:
Correct Option is : (D)
$\frac{mgR}{{{\left( \pi {{l}^{2}}\lambda {{B}_{o}} \right)}^{2}}}$

Topic: Chemistry, Electromagnetic Induction, NEET
A metallic road of length L and cross-sectional area A is heated through t oC. If Young's modulus of elasticity of the metal is Y, and the coefficient of linear expansion of the metal is Î±, then the compressional force required to prevent the rod from expanding along its length, is

Options:
A YAαt
B YAαt1-αt
C YAαt1+αt
D YA 1+αtαt

The correct answer is:
YAαt

Solution:
For linear expansion of the rod, increase in length,
ΔL=α Lt .....(i)
Now, Y=StressStrain=FLA ΔL
⇒ ΔL=FLYA
Equating equations (i) and (ii), we get
FLYA=α Lt, ⇒ F=YA α t

Topic: Physics, Thermal Properties of Matter, NEET
A metallic rod of mass per unit length 0.5 kg m-1 is lying horizontally on a smooth inclined plane which makes an angle 30o with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction 0.25 T is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is

Options:
A 14.76 A
B 5.98 A
C 7.14 A
D 11.32 A

The correct answer is:
11.32 A

Solution:
For equilibrium of conductor
ilBcos⁡θ=mgsin⁡θ
i=mglBtan⁡θ=mlgtan⁡θB
i=0.5×9.80.25×13=11.3 A.

Topic: Physics, Magnetic Effects of Current, NEET, NEET 2018
A metallic sphere cools from 50 Â°C to 40 Â°C in 300 s. If the room temperature is 20 Â°C, then its temperature in the next 5 min will be

Options:
A 38 °C
B 33.3 °C
C 30 °C
D 36 °C

The correct answer is:
33.3 °C

Solution:
According to Newton's law of cooling
Î¸1-Î¸2t=K Î¸1-Î¸2t-Î¸0
50-40300=K50+402- 20 or K= 125Ã30
40-Î¸300=K40+Î¸2- 20=KÎ¸2=Î¸1500
Or 300 Î¸=60000-1500 Î¸,
θ=600001800=33.3 ℃

Topic: Physics, Thermal Properties of Matter, NEET
A metallic square loop ABCD is moving in its own plane with velocity V in a uniform magnetic field perpendicular to its plane as shown in the figure. EMF is induced

Options:
A In AD, but not in BC
B In BC, but not in AD
C Neither in AD nor in BC
D In both AD and BC

The correct answer is:
In both AD and BC

Solution:
Wire AB and DC are parallel to velocity. So, no emf will generate. while wire AD and BC are perpendicular to velocity and magnetic field so emf will be induced.

Topic: Physics, Electromagnetic Induction, NEET
A metallic surface ejects electrons when exposed to green light of intensity I but no photoelectrons are emitted, when exposed to the yellow light of intensity I. It is possible to eject an electron from the same surface by

Options:
A Yellow light of same intensity which is more than I
B Green light of any intensity
C Red light of any intensity
D None of the above

The correct answer is:
Green light of any intensity

Solution:
λred>λviolet
VIBGYOR pattern shows that VIBG all have wavelength less than that of yellow colour and hence can initiate photoelectric effect irrespective of intensity.

Topic: Physics, Wave Optics, NEET
A metallic wire of density ρ floats horizontally in the water. The maximum radius of the wire so that the wire may not sink will be (surface tension of water =T and angle of contact θ=0°)

Options:
A 2Tπρg
B 4Tπρg
C TÏÏg
D Tρπg

The correct answer is:
2Tπρg

Solution:
2Tlcosθ=mg
2Tlcosθ=πr2lρg
For maximum radius, cosθ=1
∴r=2Tπρg

Topic: Physics, Mechanical Properties of Fluids, NEET
A method of birth control which is not used by women is

Options:
A Nirodh
B Progestasert
C Mala D
D Multiload 375

The correct answer is:
Nirodh

Solution:
In barrier methods, ovum and sperms are prevented from physically meeting with the help of barriers. Such methods are available for both males and females. Condoms are barriers made of thin rubber/ latex sheath that are used to cover the penis in the male or vagina and cervix in the female, just before coitus so that the ejaculated semen would not enter into the female reproductive tract. This can prevent conception. âNirodhâ is a popular brand of condom for the male. Use of condoms has increased in recent years due to its additional benefit of protecting the user from contracting STDs and AIDS.

Topic: Biology, Reproductive Health, NEET
A metre stick swinging in a vertical plane about a fixed horizontal axis passing through its one end undergoes small oscillation of frequency f0. If the bottom half of the stick is cut off, then its new frequency of small oscillation would become :

Options:
A f0

B 2 f0
C 2f0

D 22 f0

The correct answer is:
2 f0

Solution:
f0=12πmglI
where l is the distance between the point of suspension and centre of mass of the body.
f0=12πm.g.L2mL2/3=12π3g2L
when the bottom half of the stick is cut off
f0'=12πm2.g.L4m2L/223=12π×3gL=2 f0

Topic: Physics, Oscillations, NEET