Qstns With Ansrs Year:2022 : Neet-xii-physics

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NEET-XII-Physics

qstns with ansrs year:2022

with Solutions -

#
NEET 2022 Physics Questions with
Answer s Key Solutions

Qstn #1
Two objects of mass `` 10\, kg `` and `` 20 \, kg `` respectively are connected to the two ends of a rigid rod of length `` 10\, m `` with negligible mass. The distance of the center of mass of the system from the `` 10\, kg `` mass is :
(A) `` 5 \, m ``
(B) `` \frac{10}{3} m ``

(C) `` \frac{20}{3} m ``
(D) `` 10\, m ``
digAnsr: C
Ans :
`` X _{ CM }=\frac{20 \times 10}{20+10}=\frac{20}{3} m ``

Qstn #2

Match List - I with List - II.

List I (Electromagnetic waves)		List II (Wavelength)
a	AM radio waves	i	`` 10^{-10}m ``
b	Microwaves	ii	`` 10^2 m ``
c	Infrared radiations	iii	`` 10^{-2}m ``
d	X - rays	iv	`` 10^{-4}m ``

Choose the correct answer from the options given below:

(A)
(a) - (ii),
(b) - (iii),
(c) - (iv),
(d) - (i)
(B)
(a) - (iv),
(b) - (iii),
(c) - (ii),
(d) - (i)
(C)
(a) - (iii),
(b) - (ii),
(c) - (i),
(d) - (iv)
(D)
(a) - (iii),
(b) - (iv),
(c) - (ii),
(d) - (i)

digAnsr: A

Ans : (a) Radio wave (ii) `` \approx 10^{2} m `` (ii)
(b) Microwave `` \approx `` (iii) `` 10^{-2} m `` (iii)
(c) Infrared radiations `` \approx( iv ) 10^{-4} m `` (iv)
(d) X-ray (i) `` \approx \,Å=10^{-10} m `` (i)
(a) - (ii),
(b) - (iii),
(c) - (iv),
(d) - (i)

Qstn #3
The energy that will be ideally radiated by a `` 100 \,kW `` transmitter in `` 1 `` hour is :
(A) `` 1 \times 10^{5} J ``

(B) `` 36 \times 10^{7} J ``
(C) `` 36 \times 10^{4} J ``
(D) `` 36 \times 10^{5} J ``
digAnsr: B
Ans : `` E=P \times t=100 \times 10^{3} \times 3600 ``
`` =36 \times 10^{7} J ``

Qstn #4
An ideal gas undergoes four different processes from the same initial state as shown in the figure below. Those processes are adiabatic, isothermal, isobaric and isochoric. The curve which represents the adiabatic process among `` 1,2,3 `` and `` 4 `` is :
(A)4
(B)1

(C)2
(D)3
digAnsr: C
Ans : `` 1 : `` Isochoric
`` 2 : `` Adiabatic
`` 3 : `` Isothermal
`` 4 : `` Isobaric

Qstn #5
Plane angle and solid angle have :
(A)Both units and dimensions

(B)Units but no dimensions
(C)Dimensions but no units
(D)No units and no dimensions
digAnsr: B
Ans : Plane angle and solid angle are dimensionless but have units.

Qstn #6
In half wave rectification, if the input frequency is `` 60 \,Hz `` , then the output frequency would be:
(A) `` 120\, Hz ``
(B)zero
(C) `` 30 \,Hz ``

(D) `` 60 \,Hz ``
digAnsr: D
Ans : In half wave rectification
`` f _{ in}= f _{ out } ``
`` \Rightarrow f _{\text {out }}=60 \,Hz ``

Qstn #7
When two monochromatic lights of frequency, `` v `` and `` \frac{v}{2} `` are incident on a photoelectric metal, their stopping potential becomes `` \frac{V_{S}}{2} `` and `` V_{S} `` respectively. The threshold frequency for this metal is :

(A) `` \frac{3}{2} v ``
(B) `` 2 v ``
(C) `` 3 v ``
(D) `` \frac{2}{3} v ``
digAnsr: A
Ans : Using the equation
`` eV - hv -\phi ``
or `` eV = hv - hv _{ Th } ``
`` \frac{ eV _{ s }}{2}=\frac{ hv }{2}- hv _{ Th } ..... `` (1)
`` e V _{ s }= hv - hv _{ Th }...... `` (2)
Data Incorrect

Qstn #8
The displacement-time graphs of two moving particles make angles of `` 30^{\circ} `` and `` 45^{\circ} `` with the `` x `` -axis as shown in the figure. The ratio of their respective velocity is :

(A) `` 1: \sqrt{3} ``
(B) `` \sqrt{3}: 1 ``
(C) `` 1: 1 ``
(D) `` 1: 2 ``
digAnsr: A
Ans : Velocity is slope of `` x-t `` graph
`` V =\frac{ dx }{ dt }=\tan \theta ``
`` \frac{ V _{1}}{ V _{2}}=\frac{\tan \theta_{1}}{\tan \theta_{2}} ``
`` =\frac{\tan 30^{\circ}}{\tan 45^{\circ}}=\frac{1}{\sqrt{3}} ``

Qstn #9
The dimensions `` \left[ MLT ^{-2} A ^{-2}\right. `` ] belong to the :
(A)electric permittivity
(B)magnetic flux
(C)self inductance

(D)magnetic permeability
digAnsr: D
Ans : `` \left[ MLT ^{-2} A ^{-2}\right]= `` Magnetic permeability

Qstn #10
The peak voltage of the ac source is equal to:
(A) `` 1 / \sqrt{2} `` times the rms value of the ac source
(B)the value of voltage supplied to the circuit
(C)the rms value of the ac source

(D) `` \sqrt{2} `` times the rms value of the ac source
digAnsr: D
Ans : Peak voltage is `` \sqrt{2} `` times rms voltages in ac.

Qstn #11
The ratio of the distances travelled by a freely falling body in the `` 1^{\text {st }}, 2^{\text {nd }}, 3^{\text {rd }} `` and `` 4^{\text {th }} `` second :
(A) `` 1: 1: 1: 1 ``
(B) `` 1: 2: 3: 4 ``
(C) `` 1: 4: 9: 16 ``

(D) `` 1: 3: 5: 7 ``
digAnsr: D
Ans : `` S _{ nth }= u +\frac{ a }{2}(2 n -1) ``
`` =0+\frac{ a }{2}(2 n -1) ``
`` S _{ nth } \propto(2 n -1) ``
`` \Rightarrow S _{1 st }, S _{2 nd }, S _{3 rd }, S _{4 th } ``
`` =[2(1)-1]:[2(2)-1]:[2(3)-1]:[2(4)-1] ``
`` =1: 3: 5: 7 ``

Qstn #12
A body of mass `` 60 \,g `` experiences a gravitational force of `` 3.0 \,N `` , when placed at a particular point. The magnitude of the gravitational field intensity at that point is :
(A) `` 180 \,N / kg ``
(B) `` 0.05\, N / kg ``

(C) `` 50 \,N / kg ``
(D) `` 20\, N / kg ``
digAnsr: C
Ans : `` I_{g}=\frac{F}{m} ``
`` =\frac{3}{60 \times 10^{-3}}=50 \,N / kg ``

Qstn #13
In the given nuclear reaction, the element `` X `` is: `` { }_{11}^{22} Na \rightarrow X + e ^{+}+v ``
(A) `` { }_{12}^{22} Mg ``
(B) `` { }_{11}^{23} Na ``
(C) `` { }_{10}^{23} Ne ``

(D) `` { }_{10}^{22} Ne ``
digAnsr: D
Ans : `` { }_{11}^{22} Na \longrightarrow X +e^{+}+v ``
This is `` \beta^{+}- `` decay
`` { }_{11}^{22} Na \longrightarrow{ }_{10}^{22} Ne + e ^{+}+ v ``

Qstn #14
If a soap bubble expands, the pressure inside the bubble:
(A)is equal to the atmospheric pressure

(B)decreases
(C)increases
(D)remains the same
digAnsr: B
Ans : `` P = P _{0}+\frac{4 T }{ R } ``
`` \Rightarrow R `` increases and `` P `` decreases