Official NEET UG 2017

A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system :-

Decreases by a factor of 2
Remains the same
Increases by a factor of 2
Increases by a factor of 4

A spherical black body with a radius of 12 cm radiates 450 watt power at 500 K. If the radius were halved and the temperature doubled, the power radiated in watt would be :-

450
1000
1800
225

A carnot engine having an efficiency of\( (\frac{1}{10})\). as heat engine, is used as a refrigerator. If the work done on the system is 10 J, the amount of energy absorbed from the reservoir at lower temperature is :-

90 J
99 J
100 J
1 J

In a common emitter transistor amplifier the audio signal voltage across the collector is 3V. The resistance of collector is \(3k\Omega \). If current gain is 100 and the base resistance is \(2k\Omega \), the voltage and power gain of the amplifier is :-

15 and 200
150 and 15000
20 and 2000
200 and 1000

Figure shows a circuit that contains three identical resistors with resistance R = 9.0 \( \Omega \) each, two identical inductors with inductance L = 2.0 mH each, and an ideal battery with emf \(\varepsilon\) = 18 V. The current ‘i’ through the battery just after the switch closed is,…… :-

0.2 A
2 A
0 ampere
2 mA

A gas mixture consists of 2 moles of O_{2} and 4 moles of Ar at temperature T. Neglecting all vibrational modes, the total internal energy of the system is :-

15 RT
9 RT
11 RT
4 RT

Suppose the charge of a proton and an electron differ slightly. One of them is – e, the other is \((e+\Delta e)\). If the net of electrostatic force and gravitational force between two hydrogen atoms placed at a distance d (much greater than atomic size) apart is zero, then \(\Delta e\) is of the order of [Given mass of hydrogen\( m_{h}=1.67\times 10^{-27}kg]\)

[latex] 10_{23}C[/latex]
[latex] 10_{37}C [/latex]
[latex] 10_{47}C [/latex]
[latex] 10_{20}C [/latex]

Radioactive material ‘A’ has decay constant \( ‘8\lambda’\)and material ‘B’ has decay constant \( ‘\lambda’\). Initially they have same number of nuclei. After what time, the ratio of number of nuclei of material ‘B’ to that ‘A’ will be\( \frac{1}{e}\)

\( \frac{1}{7\lambda }\)
\(\frac{1}{8\lambda }\)
\(\frac{1}{9\lambda }\)
\(\frac{1}{\lambda }\)

An arrangement of three parallel straight wires placed perpendicular to plane of paper carrying same current ‘I along the same direction is shown in fig. Magnitude of force per unit length on the middle wire ‘B’ is given by :-

\(\)\frac{2\mu_{0}i^{2}}{\pi d}\(\)
\(\)\frac{\sqrt{2}\mu_{0}i^{2}}{\pi d}\(\)
\(\)\frac{\mu_{0}i^{2}}{\sqrt{2}\pi d}\(\)
[latex]\frac{\mu_{0}i^{2}}{{2}\pi d}[latex]

The given electrical network is equivalent to :

OR gate
NOR gate
NOT gate
AND gate

The diagrams below show regions of equipotentials:-

A positive charge is moved from A to B in each diagram.

In all the four cases the work done is the same
Minimum work is required to move q in figure (a)
Maximum work is required to move q in figure (b)
Maximum work is required to move q in figure (c)

A U tube with both ends open to the atmosphere, is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a distance of 10 mm above the water level on the other side. Meanwhile the water rises by 65 mm from its original level (see diagram). The density of the oil is :-

\( 425 kg m^{-3}\)
\(800 kg m^{-3}\)
\( 928 kg m^{-3}\)
\( 650 kg m^{-3}\)

The de-Broglie wavelength of a neutron in therma lequilibrium with heavy water at a temperature T (Kelvin) and mass m, is:-

\(\frac{h}{\sqrt{3mkT}}\)
\(\frac{2h}{\sqrt{3mkT}}\)
\(\frac{2h}{\sqrt{mkT}}\)
\(\frac{h}{\sqrt{mkT}}\)

Two astronauts are floating in gravitational free space after having lost contact with their spaceship. The two will :-

Move towards each other
Move away from each other
Will become stationary
Keep floating at the same distance between them

Which of the following statements are correct ?

(a) Centre of mass of a body always coincides with the centre of gravity of the body

(b) Central of mass of a body is the point at which the total gravitational torque on the body is zero

(c) A couple on a body produce both translational and rotation motion in a body

(d) Mechanical advantage greater than one means that small effort can be used to lift a large load

Sort elements

Which one of the following represents forward bias diode ?

1
2
3
4

The x and y coordinates of the particle at any time are x =\( 5t – 2t^{2}\) and y = 10t respectively, where x and y are in meters and t in seconds. The acceleration of the particle at t = 2s is :

\( 5\frac{m}{s^{2}}\)
\( -4\frac{m}{s^{2}}\)
[latex]-8\frac{m}{s^{2}}[/latex]
0

Which one of the following statements is correct, with reference to enzymes ?

Holoenzyme = Apoenzyme + Coenzyme
Coenzyme = Apoenzyme + Holoenzyme
Holoenzyme = Coenzyme + Co-factor
Apoenzyme = Holoenzyme + Coenzyme

A long solenoid of diameter 0.1 m has 2 × 10^{4} turns per meter. At the centre of the solenoid, a coil of 100 turns and radius 0.01 m is placed with its axis coinciding with the solenoid axis. The current in the solenoid reduces at a constant rate to 0A from 4 A in 0.05 s. If the resistance of the coil is\( 10\pi ^{2}\Omega \). the total charge flowing through the coil during this time is:-

[latex] 16\mu C[/latex]
[latex]32\mu C[/latex]
[latex]16\pi \mu C[/latex]
[latex]32\pi \mu C[/latex]

One end of string of length l is connected to a particle of mass ‘m’ and the other end is connected to a small peg on a smooth horizontal table. If the particle moves in circle with speed ‘v’ the net force on the particle (directed towards centre) will be (T represents the tension in the string) :-

\(T+\frac{mv^{2}}{l}\)
\( T_ \frac{mv^{2}}{l}\)
Zero
T

A decrease in blood pressure / volume will not cause the release of :

Atrial natriuretic factor
Aldosterone
ADH
Renin

Preeti reached the metro station and found that the escalator was not working. She walked up the stationary escalator in time \(t_{1}\) . On other days, if she remains stationary on the moving escalator, then the escalator takes her up in time \(t_{2}\). The time taken by her to walk up on the moving escalator will be

\(\)\frac{t_{1}t_{2}}{t_{2}-t_{1}}\(\)
\(\frac{t_{1}t_{2}}{t_{2}+t_{1}}\)
\(t_{1}-t_{2}\)
\(\)\frac{t_{1}+t_{2\frac{1}{1}}}{2}\(\)

A particle executes linear simple harmonic motion with an amplitude of 3 cm. When the particle is at 2 cm from the mean position, the magnitude of its velocity is equal to that of its acceleration. Then its time period in seconds is :-

\(\frac{\sqrt{5}}{2^{\pi }}\)
\(\frac{4\pi }{\sqrt{5}}\)
\(\frac{2\pi }{\sqrt{3}}\)
\(\frac{\sqrt{5}}{^{\pi }}\)

Which cells of “Crypts of Lieberkuhn” secrete antibacterial lysozyme ?

Paneth cells
Zymogen cells
Kupffer cells
Argentaffin cells

\( Young’s double slit experiment is first performed in air and then in a medium other than air. It is found that 8^{th} bright fringe in the medium lies where 5^{th} dark fringe lies in air. The refractive index of the medium is nearly \) :-

1.59
1.69
1.78
1.25

Two Polaroids\( P_{1} andP_{2} 2\) are placed with their axis perpendicular to each other.Unpolarised light\( I_{0} is incident on P_{1}.\) A third polaroid\( P_{3} \)is kept in between \(P_{1} and P_{2} \) such that its axis makes an angle

\(\frac{I_{0}}{4}\)
\(\frac{I_{0}}{8}\)
[latex]\frac{I_{0}}{16}[/latex]
[latex]\frac{I_{0}}{2}[/latex

Which of the following are not polymeric ?

Proteins
Polysaccharides
Lipids
Nucleic acids

A beam of light from a source L is incident normally on a plane mirror fixed at a certain distance x from the source. The beam is reflected back as a spot on a scale placed just above the source I. When the mirror is rotated through a small angle q, the spot of the light is found to move through a distance y on the scale. The angle \(\theta \) is given by :-

\(\) \frac{y}{x}\(\)
\(\frac{x}{2y}\)
\(\frac{x}{y}\)
\(\frac{y}{2x} \)

The bulk modulus of a spherical object is ‘B’. If it is subjected to uniform pressure ‘p’, the fractional decrease in radius is :-

\(\frac{B}{3_{p}}\)
\(\frac{3_{p}{B}}\)
\(\frac{p}{3B}\)
\(\frac{p}{B}\)

Functional megaspore in an angiosperm develops into ?

Endosperm
Embryo sac
Embryo
Ovule

A spring of force constant k is cut into lengths of ratio 1 : 2 : 3. They are connected in series and the new force constant is k’. Then they are connected in parallel and force constant is {k}” . Then k’ : {k}” is : –

1 : 9
1 : 11
1 : 14
1 : 16

If \(\theta 1 and \theta 2 be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip \theta is given by \)

\(tan_{2}\theta =tan^{2}\theta _{1}+tan^{2}\theta _{2}\)
\(cot^{2}\theta =cot^{2}\theta _{1}-cot^{2}\theta _{2}\)
\(\)tan^{2}\theta =tan^{2}\theta _{1}-tan^{2}\theta _{2}\(\)
\(cot^{2}\theta =cot^{2}\theta _{1}+cot^{2}\theta _{2}\)

In an electromagnetic wave in free space the root mean square value of the electric field is \(E_{rms} = 6V/m\). The peak value of the magnetic field is :-

\(2.83 × 10^{-8} T\)
\(\)0.70 × 10^{-8} T/\(\)
\( 4.23 × 10^{-8} T\)
\(1.41 × 10^{-8} T\)

The ratio of resolving powers of an optical microscope for two wavelengths

\(\lambda 1=4000\AA and \lambda 2=6000\AA \) is:-

9 : 4
3 : 2
16 : 81
8 : 27

Tow cars moving in opposite directions approach each other with speed of 22 m/s and 16.5 m/s respectively. The driver of the first car blows a horn having a a frequency 400 Hz. The frequency heard by the driver of the second car is [velocity of sound 340 m/s] :-

361 Hz
411 Hz
448 Hz
350 Hz

A rope is wound around a hollow cylinder of mass 3 kg and radius 40 cm. What is the angular acceleration of the cylinder if the rope is pulled with a force of 30 N ?

\( 0.25 rad/S^{2}\)
\(25 rad/S^{2} \)
\( 5 m/S^{2}\)
\(25 m/S^{2}\)

The two nearest harmonics of a tube closed at one end and open at other end are \(220 H_{z} and 260 H_{z}\) What is the fundamental frequency of the system?

[latex] 20 H_{z}[/latex]
[latex] 30H_{z}[/latex]
[latex]40 H_{z}[/latex]
[latex]10 H_{z}[/latex]

Two blocks A and B of masses 3 m and m respectively are connected by a massless and inextensible string. The whole system is suspended by a massless spring as shown in figure. The magnitudes of acceleration of A and B immediately after the string is cut, are respectively :

\(\frac{g}{3},g \)
g,g
\(\)\frac{g}{3},\frac{g}{3}\(\)
\(g \frac{g}{3} \)

[latexTwo discs of same moment of inertia rotating about their regular axis passing through centre and perpendicular to the plane of disc with angular velocities \omega _{1} and \omega _{2} . They are brought into contact face to face coinciding the axis of rotation. The expression for loss of energy during this process is[/latex:-

\( 1(\omega _{1-}\omega _{2})^{2}\)
\(\) \frac{1}{8}(\omega _{1}-\omega _{2})^{^{2}} [/latex
\((\omega _{1}-\omega _{2})^{2\)
\(\frac{1}{2}1(\omega _{1}+\omega _{2})^{2} \)

Consider a drop of rain water having mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 m/s. Take ‘g’ constant with a value 10 m/s2 . The work done by the (i) gravitational force and the (ii) resistive force of air is :-

(i) 1.25 J (ii) – 8.25 J
(i) 100 J (ii) 8.75 J
(i) 10 J (ii) – 8.75 J
(i) – 10 J (ii) – 8.25 J

A thin prism having refracting angle 10° is made of glass of refractive index 1.42. This prism is combined with another thin prism of glass of refractive index 1.7. This combination produces dispersion without deviation. The refracting angle of second prism should be :-

6°
8°
10°
4°

The photoelectric threshold wavelength of silver is \(3250 × 10^{-10}m\). The velocity of the electron ejected from a silver surface by ultraviolet light of wavelength \(2536 × 10^{-10} m \)is :-

(Given)\( h = 4.14 × 10^{-15} eVs and c = 3 × 10^{8} ms^{-1}\)

\( \approx 0.6 × 10^{6} ms^{-1}\)
\( \approx 61 × 10^{3} ms^{-1}\)
\(\approx 0.3 × 10^{6} ms^{-1}\)
\(\approx 6 × 10^{5} ms^{-1}\)

A physical quantity of the dimensions of length that can be formed out of c, G and \(\frac{e^{2}}{4\pi \varepsilon _{0}}\) is [c is velocity of light, G is universal constant of gravitation and e is charge] :-

\(c^{2}\left [ G\frac{e^{2}}{4\pi \varepsilon _{0}} \right ]^{\frac{1}{2}}\)
\(\frac{1}{c^{2}}\left [ \frac{e^{2}}{G4\pi \varepsilon _{0}} \right ]^{\frac{1}{2}}\)
\(\frac{1}{c}G\frac{e^{2}}{4\pi \varepsilon _{0}}\)
\(\frac{1}{c^{2}}\left [ G\frac{e^{2}}{4\pi \varepsilon _{0}} \right ]^{\frac{1}{2}}\)

The acceleration due to gravity at a height 1 km above the earth is the same as at a depth d below the surface of earth. Then :-

d = 1 k
\( d = \frac{3}{2}km\)
d = 2 km
\(d = \frac{1}{2} km\)

A 250-Turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 µA and subjected to magnetic field of strength 0.85 T. Work done for rotating the coil by 180º against the torque is:-

4.55 µJ
2.3 µJ
1.15 µ J
9.1 µ J

Two rods A and B of different materials are welded together as shown in figure. Their thermal conductivities are \(K_{1} and K_{1}\). The thermal conductivity of the composite rod will be:

[latex]3\frac{(K_{1}+K_{2})}{2}[/latex]
[latex]K_{1}+K_{2}[/latex]
[latex]2(K_{1}+K_{2})[/latex]
[latex]\frac{K_{1}+K_{2}}{2} [/latex]

A potentiometer is an accurate and versatile device to make electrical measurements of E.M.F. because the method involves :-

Potential gradient
A condition of no current flow through the galvanometer
A combination of cells, galvanometer andresistances
Cells

The ratio of wavelengths of the last line of Balmer series and the last line of Lyman series is :-

1
4
0.4
2