CBSE Class 12 Physics – Marking Scheme 2022 - 2023 - Download
Learning without understanding is not helps the students to attain the best scores in exams. For helping those enthusiastic students, who want to prove their best, our CBSE tips website helps by providing way to reach high scores. we are very proud to give you a lot of collections of CBSE Sample Question Papers and Marking Scheme in PDF format.
CBSE Class 12 Physics – Sample Question Papers and Answer Keys 2022-2023 - Download
Learning without understanding is not helps the students to attain the best scores in exams. For helping those enthusiastic students, who want to prove their best, our CBSE tips website helps by providing way to reach high scores. we are very proud to give you a lot of collections of CBSE Sample Question Papers and Answer Keys in PDF format
Every year CBSE conducts board exams for 12th standard. These exams are very competitive to all the students. So our website provides online tests for all the 12th subjects. These tests are also very effective and useful for those who preparing for competitive exams like NEET, JEE, CA etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
These online tests are based on latest CBSE Class 12 syllabus. While attempting these our students can identify the weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly.
Question 1.
Digital signals:
(a) deal with all sort of values
(b) can use decimal system
(c) can use binary system
(d) (b) and (c) both
Answer: (d) (b) and (c) both
Question 2.
Which of the following is not transducer?
(a) Loudspeaker
(b) Amplifier
(c) Microphone
(d) All
Answer: (b) Amplifier
Question 3.
The space waves which are affected seriously by atmospheric conditions are:
(a) MF
(b) HUF
(c) VHF
(d) UHF
Answer: (d) UHF
Question 4.
Increase in frequency deviation results into:
(a) increase in noise of FM receiver
(b) decrease in noise of AM receiver
(c) increase in noise of Am receiver
(d) decrease in noise of FM receiver
Answer: (b) decrease in noise of AM receiver
Question 5.
An antenna is:
(a) Inductive
(b) Capacitive
(c) Resistive
(d) A transformer
Answer: (a) Inductive
Question 6.
AM is used for broadcasting because:
(a) it is more noise immune than other modulation system
(b) it requires less transmitting power compare with other systems
(c) its use avoids receiver complexity
(d) No other modulation system can provide the necessary bandwidth faithful transmission
Answer: (c) its use avoids receiver complexity
Question 7.
Broadcasting antenna are generally:
(a) Ommi directional type
(b) Vertical type
(c) Horizontal type
(d) None
Answer: (b) Vertical type
Question 8.
Who undertook the first space walk and in which year?
(a) Leonov 1965
(b) Neil Armstrong, 1969
(c) Rakesh Sharma. 1998
(d) None of these
Answer: (a) Leonov 1965
Question 9.
The modulation index in amplitude modulation is:
(a) Always zero
(b) Between 0 and 1
(c) Between 1 and ∞
(d) None of these
Answer: (c) Between 1 and ∞
Question 10.
The output of a digital computer is an example of:
(a) digital signal
(b) analog signal
(c) both (a) and (b)
(d) neither (a) nor (b)
Answer: (a) digital signal
Question 11.
The term used “to collect the information about an object and a place without physical contact” is called :
(a) modulation
(b) communication
(c) amplification
(d) remote sensing
Answer: (d) remote sensing
Question 12.
Name the man who was first to place his foot on the moon and in which year:
(a) Neil Armstrong, 1969
(b) James Van A lien, 1971
(c) Leonov, 1965
(d) None of these
Answer: (a) Neil Armstrong, 1969
Question 13.
A microphone converts:
(a) sound signals into electrical signals
(b) electrical signals into sound signals
(c) both (a) and (b)
(d) Neither (a) nor (b)
Answer: (a) sound signals into electrical signals
Question 14.
The wavelength of a wave of frequency 10 kHz is:
(a) 30 m
(b) 300 m
(c) 30 km
(d) 300 km
Answer: (c) 30 km
Question 15.
A loudspeaker converts:
(a) electrical signals into sound signals
(b) sound signals into electrical signals
(c) both (a) and (b)
(d) neither (a) nor (b)
Answer: (a) electrical signals into sound signals
Question 16.
The sound produced by a tuning fork is a sort of:
(a) analog signal
(b) digital signal
(c) both (a) and (b)
(d) neither (a) nor (b)
Answer: (a) analog signal
Question 17.
The velocity of electromagnetic wave is:
(a) 3 × 105 ms-1
(b) 3 × 106 ms-1
(c) 3 × 108 ms-1
(d) 3 × 1010 ms-1
Answer: (c) 3 × 108 ms-1
Question 18.
The audio frequencies range from:
(a) 20 Hz to 20.000 kHz
(b) 20 Hz to 20 kHz
(c) 20 kHz to 20.000 kHz
(d) None of these
Answer: (b) 20 Hz to 20 kHz
Question 19.
The length of a half wave dipole at 30 mega-hertz is:
(a) 5 m
(b) 10 m
(c) 25 m
(d) 80 m
Answer: (a) 5 m
Question 20.
In space communication, the sound waves can be sent from one place to another:
(a) through space
(b) through wires
(c) by superimposing it on undamped electro-magnetic waves
(d) by superimposing it on damped electro-magnetic waves
Answer: (c) by superimposing it on undamped electro-magnetic waves
Question 21.
The area served by an antenna of height 100 m is:
(a) 109m²
(b) 4 × 109 m²
(c) 6 × 109m²
(d) 8 × 1010m²
Answer: (b) 4 × 109 m²
Question 22.
The output of a digital computer is an example of:
(a) digital signal
(b) analog signal
(c) both (a) and (b) above
(d) neither (a) nor (b)
Answer: (a) digital signal
Question 23.
Which is more advantageous?
(a) analog data communication
(b) digital data communication
(c) both (a) and (b) are equally good
(d) depends on the situation
Answer: (b) digital data communication
Question 24.
Communication channel consists of:
(a) transmission line only
(b) optical fibre only
(c) free space only
(d) All of the above
Answer: (d) All of the above
Question 25.
Digital signals:
(a) represents values as discrete steps
(b) Do not represents values as discrete steps
(c) represent values steps
(d) represent random steps
Answer: (a) represents values as discrete steps
Every year CBSE conducts board exams for 12th standard. These exams are very competitive to all the students. So our website provides online tests for all the 12th subjects. These tests are also very effective and useful for those who preparing for competitive exams like NEET, JEE, CA etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
These online tests are based on latest CBSE Class 12 syllabus. While attempting these our students can identify the weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly.
Question 1.
Main function of a transistor is to :
(a) rectify
(b) simplify
(c) amplify
(d) all the above
Answer: (c) amplify
Question 2.
To obtain p-type silicon semiconductor, we need to dope pure silicon with:
(a) aluminium
(b) phosphorus
(c) oxygen
(d)germanium
Answer: (a) aluminium
Question 3.
In intrinsic semiconductor at room temperature, the number of electrons and holes are:
(a) equal
(b) unequal
(c) infinite
(d) zero
Answer: (a) equal
Question 4.
On applying reverse bias to a junction diode, it:
(a) lowers the potential barrier
(b) raise the potential barrier
(c) increases the majority carrier current
(d) increases the minority carrier current
Answer: (b) raise the potential barrier
Question 5.
With fall of temperature, the forbidden energy gap of a semiconductor
(a) increases
(b) decreases
(c) sometimes increases and sometimes decreases
(d) remains unchanged
Answer: (d) remains unchanged
Question 6.
For germanium crystal, the forbidden energy gap in joules
(a) 1.216 × 10-19
(b) 1.76 × 10-19
(c) 1.6 × 10-19
(d) zero
Answer: (a) 1.216 × 10-19
Question 7.
Number of electrons in the valence shell of a semiconductor is:
(a) 1
(b) 2
(c) 3
(d) 4
Answer: (d) 4
Question 8.
To obtain electrons as majority charge carriers in a semiconductors the impurity mixed is:
(a) monovalent
(b) divalent
(c) trivalent
(d) pentavalent
Answer: (b) divalent
Question 9.
In the middle of the depletion layer of a reverse biased p-n junction, the:
(a) electric field is zero
(b) potential is maximum
(c) electric field is maximum
(d) potential zero.
Answer: (d) potential zero.
Question 10.
Bonds in a semiconductor :
(a) trivalent
(b) covalent
(c) bivalent
(d) monovalent
Answer: (b) covalent
Question 11.
In a common base amplifier the phase difference between the input signal voltage and output voltage is :
(a) π/2
(b) 0
(c) π/4
(d) π
Answer: (b) 0
Question 12.
Energy bands in solids are a consequence of:
(a) Ohm’s Law
(b) Pauli’s exclusion principle
(c) Bohr’s theory
(d) Heisenberg’s uncertainty principle
Answer: (b) Pauli’s exclusion principle
Question 13.
Semiconductors of both p-type and n-type are produced by:
(a) ionic solids
(b) covalent solids
(c) metallic solids
(d) molecular solids
Answer: (b) covalent solids
Question 14.
In semi conductor which are responsible for conduction:
(a) only electron
(b) electron and hole both
(c) only hole
(d) None of these
Answer: (b) electron and hole both
Question 15.
In a p-type semiconductor, current conduction is by:
(a) atoms
(b) holes
(c) electrons
(d) protons
Answer: (b) holes
Question 16.
In binary system III represents:
(a) 1
(b) 3
(c) 7
(d) 100
Answer: (c) 7
Question 17.
On heating, resistance of semiconductors:
(a) decreases
(b) increases
(c) remains same
(d) first increases then decreases
Answer: (a) decreases
Question 18.
The relation between number of free electrons (n) in a semiconductor and temperature (T) is given by:
(a) n ∝ T
(b) n ∝ T²
(c) n ∝ T1/2
(d) n ∝ T3/2
Answer: (d) n ∝ T3/2
Question 19.
p-n junction diode can be used as:
(a) amplifier
(b) oscillator
(c) detector
(d) modulator
Answer: (c) detector
Question 20.
In reverse biasing:
(a) large amount of current flows
(b) no current flows
(c) potential barrier across junction increases
(d) depletion layer resistance increases
Answer: (c) potential barrier across junction increases
Every year CBSE conducts board exams for 12th standard. These exams are very competitive to all the students. So our website provides online tests for all the 12th subjects. These tests are also very effective and useful for those who preparing for competitive exams like NEET, JEE, CA etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
These online tests are based on latest CBSE Class 12 syllabus. While attempting these our students can identify the weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly.
Question 1.
The half life of a radioactive decay is n times its mean life, n is equal to:
(a) 0.6930
(b) 0.0693
(c) \(\frac{1}{0.6930}\)
(d) 0.3070
Answer: (a) 0.6930
Question 2.
An electron and a positron each having a mass equivalent to 0.53 MeV annihilate each other and produce a photon. The minimum energy of the photon is.
(a) 0.53 MeV
(b) 1.06 MeV
(c) 2.12 MeV
(d) zero
Answer: (b) 1.06 MeV
Question 3.
If radio active nuclei emits β-particle, then mass-number:
(a) increased by 1 unit
(b) decreases by 1 unit
(c) increases by 2 unit
(d) decreases by 2 unit
Answer: (a) increased by 1 unit
Question 4.
Rutherford is the unit of:
(a) radioactivity
(b) energy
(c) photoelectric current
(d) magnetic field
Answer: (a) radioactivity
Question 5.
The wavelength of y-rays is of the order of:
(a) 10-8 m
(b) 10-5 m
(c) 10-11 m
(d) 10-22 m
Answer: (c) 10-11 m
Question 6.
How many electrons are contained in \(_{92}^{238}\)U nucleus?
(a) 92
(b) 146
(c) 238
(d) 0
Answer: (d) 0
Question 7.
Radius of 1st Bohr orbit is a0 (= 0.529 Ã…) What is the radius of 2nd Bohr orbit?
(a) 10-8
(b) 2a0
(c) 4a0
(d) 2√2a0
Answer: (c) 4a0
Question 8.
According to Yukawa’s theory of nuclear forces, the origin of nuclear force between nucleons is due to the exchange of
(a) mesons
(b) photons
(c) electrons
(d) positrons
Answer: (b) photons
Question 9.
The ground state energy of Hydrogen atom is -13.6 eV. What is the potential energy of electron in this state?
(a) 0 eV
(b) -13.6 eV
(c) 2 eV
(d) -27.2 eV
Answer: (d) -27.2 eV
Question 10.
Which of the following atoms has the lowest ionization potential?
(a) \(_{8}^{8}\)O
(b) \(_{7}^{14}\)N
(c) \(_{55}^{133}\)Cs
(d) \(_{18}^{40}\)Ar
Answer: (c) \(_{55}^{133}\)Cs
Question 11.
Nuclear force is:
(a) strong, short range and charge independent force
(b) charge independent, attractive and long range force
(c) strong, charge dependent and short range attractive force
(d) long range, change dependent and attractive force
Answer: (a) strong, short range and charge independent force
Question 12.
In the given reaction:
\(_{Z}^{A}\)X → \(_{Z+1}^{A}\) Y → \(_{Z-1}^{A-4}\) K → \(_{Z-1}^{A-4}\) K radioactive radiations are emitted in the sequence
(a) α, β, γ
(b) β, α, γ
(c) γ, α, β
(d) β, γ, α
Answer: (b) β, α, γ
Question 13.
An alpha particle is emitted from \(_{88}\)Ra\(^{226}\), then the product nuclei has:
(a) Z = 84, A = 224
(b) Z = 86, A = 224
(c) Z = 86, A = 222
(d) Z = 82, A = 222
Answer: (c) Z = 86, A = 222
Question 14.
The Bohr model of atom:
(a) assumes that the angular momentum of electron is quantized
(b) uses Einstein’s photoelectric equation
(c) predicts continuous emission spectra for atoms
(d) predicts the same emission spectra for all types of atoms
Answer: (a) assumes that the angular momentum of electron is quantized
Question 15.
X-ray was discovered by :
(a) Becqueral
(b) Marie curie
(c) Roengton
(d) Vanlaw
Answer: (c) Roengton
Question 16.
Fusion takes place at high temperature because:
(a) Atom are ionised at high temperature
(b) Molecules break up at high temperature
(c) Nuclei break up at high temp.
(d) Kinetic energy is high enough to overcome repulsion between nuclei
Answer: (d) Kinetic energy is high enough to overcome repulsion between nuclei
Question 17.
The order of nuclear density is :
(a) 103
(b) 1017
(c) 106
(d) None
Answer: (b) 1017
Question 18.
Chadwick was awarded the Nobel prize in Physics in 1935 for his discovery of:
(a) electron
(b) proton
(c) neutron
(d) None of these
Answer: (c) neutron
Question 19.
The helium atom does not contain
(a) two protons
(b) two electrons
(c) two neutrons
(d) six nucleons
Answer: (d) six nucleons
Question 20.
The density of a nucleus is of the order of:
(a) 1015 kg m-3
(b) 1018 kg m-3
(c) 1017 kg m-3
(d) 1016 kg m-3
Answer: (c) 1017 kg m-3
Question 21.
The isotope generally used for the treatment of cancer is:
(a) I131
(b) Hg197
(c) O15
(d) Co60
Answer: (d) Co60
Question 22.
When the mass of a sample of a radioactive substance decreases, the mean life of the sample:
(a) increases
(b) decreases
(c) remain unchanged
(d) first decreases then increases
Answer: (c) remain unchanged
Question 23.
What percentage of radioactive substance is left after 5 half lives?
(a) 3.125%
(b) 6.25%
(c) 12.33%
(d) 31%
Answer: (a) 3.125%
Question 24.
Alpha particle emitted from a radioactive material are:
(a) Helium nuclei
(b) Hydrogen nuclei
(c) Lithium nuclei
(d) None of the above
Answer: (a) Helium nuclei
Question 25.
Mass is converted into energy according to the relation:
(a) E = me²
(b) E = mgh
(c) E = \(\frac{3}{2}\)me²
(d) E = \(\frac{mgH}{c^2}\)
Answer: (a) E = me²
