Q.1
World Ozone Day is celebrated on
  • \(16^{th}\) September
  • \( 22^{nd}\) April
  • \(5^{th}\) June
  • \(21^{st}\) April
Q.2
The correct order of atomic radii in group 13 elements is
  • B < A1 < Ga < In < Tl
  • B < Ga < A1 < In < Tl
  • B < A1 < In < Ga < Tl
  • B < Ga < A1 < Tl < In
Q.3
Which of the following flowers only once in its life-time?
  • Jackfruit
  • Bamboo species
  • Papaya
  • Mango
Q.4
A toy car with charge \(q\) moves on a friction less horizontal plane surface under the influence of a uniform electric field (\vec{E}\). Due to the force (q\vec{E}\), its velocity increases from 0 to 6 m/s in one second duration. At that instant the direction of the field is reversed. The car continuous to move for two more seconds under the influence of this field. The average velocity and the average speed of the toy car between 0 to 3 seconds are respectively
  • 1 m/s, 3.5 m/s
  • 1 m/s, 3 m/s
  • 2 m/s, 3 m/s
  • 1.5 m/s, 3 m/s
Q.5
At what temperature will the rms speed of oxygen molecules become just sufficient for escaping from the Earth’s atmosphere? Given that Mass of oxygen molecule  \(m = 2.76\times 10^{-26}kg\) Boltzmann's constant \(k_B = 1.38\times 10^{-23} JK^{-1}\)
  • \(1.254 \times 10^4\, K\)
  • \(2.508 \times 10^4\, K\)
  • \(5.016 \times 10^4\, K\)
  • \(8.360 \times 10^4\, K\)
Q.6
A student measured the diameter of a small steel ball using a screw gauge of least count 0.001 cm. the main scale reading is 5 mm and zero of circular scale division coincides with 25 divisions above the reference level. If screw gauge has a zero error of – 0.004 cm, the correct diameter of the ball is
  • 0.053 cm
  • 0.529 cm
  • 0.525 cm
  • 0.521 cm
Q.7
Three objects, A : (a solid sphere), B : (a thin circular disk) and C : (a circular ring), each have the same mass \(M\) and radius \(R\), They all spin with the same angular speed \(\omega \) about their own symmetry axes. The amounts of work \(W\) required to bring them to rest, would satisfy the relation
  • \(W_B>W_A>W_C\)
  • \(W_C>W_B>W_A\)
  • \(W_A>W_C>W_B\)
  • \(W_A>W_B>W_C\)
Q.8
The moment of the force, \(\vec{F} = 4 \hat{i} + 5\hat{ j} – 6\hat{ k}\) at \((2,0,-3)\), about the point \((2,-2, -2)\), is given by
  • \(– 7 \hat{i} –4 \hat{j} -8 \hat{k}\)
  • \(– 7 \hat{i} -8 \hat{j} -4 \hat{k}\)
  • \(– 8 \hat{i} –4 \hat{j} -7 \hat{k}\)
  • \(– 4 \hat{i} – \hat{j} -8 \hat{k}\)
Q.9
In the combination of the following gates the output Y . can be written in terms of inputs A and B as
neet-18-ph-q17.png
  • \( \overline{A\cdot B}\)
  • \( \overline{A\cdot B}+A\cdot B \)
  • \( \overline{A+B}\)
  • \( A\cdot \overline{B}+\overline{A}\cdot B \)
Q.10
The refractive index of the material of a prism is \(\sqrt{2}\) and the angle of the prism is \(30^0\) . One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is
  • \(45^0\)
  • \(60^0\)
  • \(zero\)
  • \(30^0\)
Q.11
An object is placed at a distance of 40 cm from a concave mirror of focal length 15 cm. If the object is displaced through a distance of 20 cm towards the mirror, the displacement of the image will be
  • 36 cm away from the mirror
  • 36 cm towards the mirror
  • 30 cm away from the mirror
  • 30 cm towards the mirror
Q.12
The volume \(V\) of a monatomic gas varies with its temperature \(T\), as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state \(A\) to state \(B\), is
neet-18-ph1.png
  • \(\frac{2}{3}\)
  • \(\frac{2}{5}\)
  • \(\frac{1}{3}\)
  • \(\frac{2}{7}\)
Q.13
A moving block having mass \(m\), collides with another stationary block having mass \(4m\). The lighter block comes to rest after collision. When the initial velocity of the lighter block is \(v\), then the value of coefficient of restitution \(e\) will be
  • 0.8
  • 0.5
  • 0.4
  • 0.25
Q.14
A set of \(n\) equal resistors, of value \(R\) each, are connected in series to a battery of emf \(E\) and internal resistance \(R\). The current drawn is \(I\). Now, the \(n\) resistors are connected in parallel to the same battery. Then the current drawn from battery becomes \(10\, I\). The value of \(n\) is
  • 20
  • 9
  • 11
  • 10
Q.15
Unpolarised light is incident from air on a plane surface of material of refractive index \(\mu\). At a particular angle of incidence \(i\), it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation ?
  • Reflected light is polarized with its electric vector parallel to the plane of incidence.
  • \(i=\tan ^{-1}\left( \frac{1}{\mu} \right) \)
  • Reflected light is polarized with its electric vector perpendicular to the plane of incidence.
  • \(i=\sin ^{-1}\left( \frac{1}{\mu} \right) \)
Q.16
For a radioactive material, half-life is 10 minutes. If initially there are 600 numbers of nuclei, the time taken (in minutes) for the disintegration of 450 nuclei is
  • 10
  • 20
  • 30
  • 15
Q.17
A body initially at rest and sliding along a friction less track from a height \(h\) (as shown in the figure) just completes a vertical circle of diameter \(AB = D\). The height \(h\) is equal to
neet-18-ph-q30.png
  • \(\frac{7}{5}D\)
  • \(D\)
  • \(\frac{3}{2}D\)
  • \(\frac{5}{4}D\)
Q.18
Two wires are made of the same volume. The first wire has cross-sectional area \(A\) and the second wire has cross-sectional area \(3A\). if the length of the first wire is increased by \(\Delta l\) on applying a force \(F\), how much force is needed to stretch the second wire by the same amount ?
  • \(F\)
  • \(9 F\)
  • \(4 F\)
  • \(6 F\)
Q.19
The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is 20 cm, the length of the open organ pipe is
  • 8 cm
  • 16 cm
  • 12.5 cm
  • 13.2 cm
Q.20
An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of
  • Large focal length and small diameter
  • Small focal length and large diameter
  • Large focal length and large diameter
  • Small focal length and small diameter
Q.21
The magnetic potential energy stored in a certain inductor is \(25\, mJ\) , When the current in the inductor is \(60\, mA\). This inductor is of inductance
  • 138.88 H
  • 0.138 H
  • 1.389 H
  • 13.89 H
Q.22
The electrostatic force between the metal plates of an isolated parallel plate capacitor \(C\) having a charge \(Q\) and area \(A\), is
  • Proportional to the square root of the distance between the plates.
  • inversely proportional to the distance between the plates.
  • Linearly proportional to the distance between the plates
  • Independent of the distance between the plates.
Q.23
In Young’s double sit experiment the separation d between the slits is \(2\,mm\), the wavelength  \(\lambda\) of the light used is 5896 Å  and distance \(D\) between the screen and slits is 100 cm. it is found that the angular width of the fringes is \(0.20^{\circ}\). To increase the fringe angular width to \(0.21^{\circ}\) (with same \(\lambda\) and \(D\) ) the separation between the slits needs to be changed to
  • 1.8 mm
  • 1.9 mm
  • 2.1 mm
  • 1.7 mm
Q.24
A pendulum is hung from the roof of a sufficiently high building and is moving freely to and fro like a simple harmonic oscillator. The acceleration of the bob of the pendulum is \(20\,\, m/s^2\) at a distance of 5 m from the mean position. The time period of oscillation is
  • \(1 s\)
  • \(2 s\)
  • \(\pi s\)
  • \(2\pi s\)
Q.25
In the circuit shown in the figure, the input voltage \(V_{i}\) is \(20 V\), \(V_{BE}=0\) and \(V_{CE}=0\). The values of \(I_{B}\), \(I_C\) and \(\beta\) are given by
neet-18-ph-q15.png
  • \(I_B =\text{40 }\mu A, I_C=\text{10 }mA, \beta =250\)
  • \(I_B =\text{25 }\mu A, I_C=\text{5 }mA, \beta =200\)
  • \(I_B =\text{20 }\mu A, I_C=\text{5 }mA, \beta =250\)
  • \(I_B =\text{40 }\mu A, I_C=\text{5 }mA, \beta =125\)
Q.26
An electron falls from rest through a vertical distance \(h\) in a uniform and vertically upward directed electric field \(E\). The direction of electric field is now reversed, keeping its magnitude the same. A proton is allowed to fall from rest in it through the same vertical distance \(h\). The time of fall of the electron, in comparison to the time of fall of the proton is
  • smaller
  • equal
  • 10 times greater
  • 5 times greater
Q.27
The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is
  • 1: -1
  • 2: -1
  • 1: -2
  • 1: 1
Q.28
A turning fork is used to produce resonance in a glass tube. The length of the air column in this tube can be adjusted by a variable piston. At room temperature of \(27^0C\) two successive resonances are produced at 20 cm and 73 cm of column length. If the frequency of the tuning fork is 320 Hz, the velocity of sound in air at \(27^0C\) is
  • 300 m/s
  • 350 m/s
  • 339 m//s
  • 330 m/s
Q.29
If the mass of the sun were ten times smaller and the universal gravitational constant were ten times larger in magnitude, which of the following is not correct?
  • Raindrops will fall faster
  • Time period of a simple pendulum of the Earth would decrease
  • \(g\) on the Earth will not change
  • Walking on the ground would become more difficult.
Q.30
An electron of mass m with an initial velocity \(\vec{V}=V_0 \hat{i} \left( V_0>0 \right) \) enters an electric field  \(\vec{E}=-E_0 \vec{i} \left( E_0=constant>0 \right)\)  at \(t=0\). If \(\lambda _0\) is its de-Broglie wavelength initially, then its de-Broglie wavelength at time \(t\) is
  • \( \lambda _0\left( 1+\frac{eE_0}{mV_0}t \right) \)
  • \( \frac{\lambda _0}{\left( 1+\frac{eE_0}{mV_0}t \right)} \)
  • \( \lambda _0t\)
  • \( \lambda _0\)
0 h : 0 m : 1 s