ktet category 3 physical science question paper with solution
KTET Category III – Physical Science 2018
Questions 1–80 | Answers & Detailed Solutions
1. The acceleration due to gravity does not depend on:
Correct Answer: (C) Mass of the body
Solution:
The acceleration due to gravity is given by:
g = GM / R²
Here, M is the mass of the Earth and R is its radius.
The mass of the falling body does not affect the value of g.
2. If F is the force of attraction between two bodies of masses m₁ and m₂, what about the force between masses 2m₁ and m₂ kept at a distance 4d?
Correct Answer: (D) F/8
Solution:
According to Newton’s law of gravitation:
F = Gm₁m₂ / d²
New force:
F’ = G(2m₁)m₂ / (4d)²
Therefore:
F’ = 2Gm₁m₂ / 16d² = F/8
Hence the required force is F/8.
3. Examine the circuits given below. Choose the correct statement related to the brightness of the lamps when the switch is ON.
Correct Answer: (A) In circuit (I), lamp glows brighter
Solution:
Circuit I uses DC whereas circuit II uses AC with an inductive coil.
The inductive reactance in the AC circuit opposes the flow of current.
Therefore, the current through the lamp in circuit II is lower.
Hence the lamp in circuit I glows brighter.
4. Which among the following will favour the backward reaction for a reversible reaction at equilibrium?
Correct Answer: (C) Increasing the concentration of any of the products
Solution:
According to Le Chatelier’s principle, when the concentration of a product
is increased, the equilibrium shifts in the backward direction to reduce
the excess product.
5. Calculate the amount of heat generated in a conductor of resistance 4 Ω, when 2 A electric current flows through it for 1 hr.
Correct Answer: (C) 57600 J
Solution:
Joule’s law of heating:
H = I²Rt
Given:
I = 2 A, R = 4 Ω, t = 1 hour = 3600 s
H = (2)² × 4 × 3600
H = 57600 J
Therefore, the heat generated is 57600 J.
6. The expression for angular velocity is:
Correct Answer: (A) ω = 2πν
Solution:
Angular velocity is related to frequency by:
ω = 2πf
Therefore, ω = 2πν.
7. Which materials will you choose for the preparation of more CO₂ in less time from the given materials?
Correct Answer: (C) Marble powder and concentrated HCl
Solution:
The reaction is:
CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂
Marble powder has a larger surface area than marble pieces.
A higher concentration of HCl also increases the rate of reaction.
Therefore, marble powder and concentrated HCl produce CO₂ faster.
8. Which of the following is a redox reaction?
Correct Answer: (D) Mg + 2HCl → MgCl₂ + H₂
Solution:
Magnesium loses electrons and is oxidised:
Mg → Mg²⁺ + 2e⁻
Hydrogen ions gain electrons and are reduced to hydrogen gas.
Since oxidation and reduction occur simultaneously, it is a redox reaction.
9. The numerical value of N/n, where N is the number of molecules and n is the number of moles of gas, is:
Correct Answer: (C) 6.022 × 10²³
Solution:
The number of particles present in one mole is Avogadro’s number:
Nₐ = 6.022 × 10²³ mol⁻¹
Therefore N/n = 6.022 × 10²³.
10. Find the odd one out.
Correct Answer: (A) Mesons
Solution:
Fermionic condensate, superfluid and Bose-Einstein condensate are
quantum states or phenomena of matter. Mesons are subatomic particles.
Hence, Mesons are the odd one out.
11. The process of converting AC to DC is called:
Correct Answer: (A) Rectification
Solution:
Rectification is the process of converting alternating current (AC)
into direct current (DC). Diodes are commonly used for this purpose.
12. Law of Octaves was put forward by:
Correct Answer: (B) J.A.R. Newlands
Solution:
J.A.R. Newlands proposed the Law of Octaves in 1865.
He observed that every eighth element showed similarities in properties
when elements were arranged according to increasing atomic mass.
13. The pseudo-transition elements are:
Correct Answer: (D) Zn, Cd, Hg
Solution:
Zinc, cadmium and mercury have completely filled d-subshells
(d¹⁰ configuration). They do not show many characteristic properties
of transition elements and are therefore called pseudo-transition elements.
14. How many galvanic cells can be constructed between the metals Mg, Zn, Ni and Pb?
Correct Answer: (D) 6
Solution:
Four different metals can be paired in:
⁴C₂ = 4 × 3 / 2 = 6
Therefore, six galvanic cells can be constructed.
15. When the product of pressure and volume is plotted against pressure,
at constant temperature for a given amount of gas, the line obtained is:
Correct Answer: (A) Parallel to x-axis
Solution:
According to Boyle’s law:
PV = Constant
Therefore, a graph of PV against pressure is a horizontal straight line,
parallel to the x-axis.
16. Which among the following acids can produce three different types of salts?
Correct Answer: (C) Phosphoric acid
Solution:
Phosphoric acid is tribasic:
H₃PO₄
It can form three types of salts by successive replacement of H⁺ ions:
NaH₂PO₄, Na₂HPO₄ and Na₃PO₄.
17. Identify the elementary particle discovered in 2012 at the CERN laboratory.
Correct Answer: (B) Higgs Boson
Solution:
The Higgs boson was experimentally observed at CERN in 2012.
It is associated with the Higgs field and helps explain how elementary
particles acquire mass.
18. How many resistors of 150 Ω should be connected in parallel to get 4 A current from 200 V supply?
Correct Answer: (A) 3
Solution:
Required equivalent resistance:
R = V/I = 200/4 = 50 Ω
For n identical resistors in parallel:
Req = 150/n
Therefore:
150/n = 50
Hence:
n = 3
19. A particle moving with a certain velocity is subjected to a retardation of 10 m/s². If the particle returns to the starting point in 20 s, calculate the initial velocity.
Correct Answer: (C) 100 m/s
Solution:
Since the particle returns to its starting point:
s = ut – ½at² = 0
Therefore:
u = at/2
u = (10 × 20)/2 = 100 m/s
Hence initial velocity = 100 m/s.
20. Which is the force responsible for the surface tension between the molecules on the surface of a liquid?
Correct Answer: (C) Cohesion force
Solution:
Cohesive forces are attractive forces between molecules of the same
substance. These forces produce surface tension in liquids.
21. In soap manufacturing, glycerol from spent lye was removed by:
Correct Answer: (B) Distillation under reduced pressure
Solution:
Glycerol has a high boiling point. Distillation under reduced pressure
lowers its boiling point and permits separation without excessive heating.
22. The power of a lens prescribed by a doctor is –1.5 D. What is its focal length?
Correct Answer: (B) 67 cm
Solution:
Formula:
P = 1/f
Therefore:
f = 1/−1.5 = −0.667 m
Converting into centimetres:
f ≈ −66.7 cm
Thus the magnitude is approximately 67 cm.
The negative sign indicates a concave lens.
23. How much will a temperature of 60°C be in Fahrenheit scale?
Correct Answer: (C) 140°F
Solution:
F = (9/5)C + 32
F = (9/5 × 60) + 32 = 108 + 32 = 140°F
24. The persistence or prolongation of sound after the source has stopped producing sound is called:
Correct Answer: (D) Reverberation
Solution:
Reverberation is the persistence of sound caused by repeated reflections
of sound waves even after the source has stopped producing sound.
25. The tuning fork of frequency 256 Hz is excited and placed near a resonance column. When the inner tube is raised, the sound increases gradually because:
Correct Answer: (B) The natural frequency of tuning fork is equal to the frequency of air column
Solution:
At resonance, the natural frequency of the air column becomes equal to
the frequency of the tuning fork. The amplitude and sound intensity
become maximum.
26. Which of the given properties does not belong to a paramagnetic material?
Correct Answer: (B) The molecules have zero magnetic dipole moments
Solution:
Paramagnetic substances contain unpaired electrons and therefore have
magnetic dipole moments. Hence the statement that their molecules have
zero magnetic dipole moments is incorrect.
27. Number of atoms present in 18 g of carbon is:
Correct Answer: (B) 9.033 × 10²³
Solution:
Molar mass of carbon = 12 g/mol.
Number of moles = 18/12 = 1.5 mol
Number of atoms:
1.5 × 6.022 × 10²³ = 9.033 × 10²³
28. The quantity of heat required to convert 10 kg of ice at 0°C into water at the same temperature is. Latent heat of fusion of ice = 335 × 10³ J/kg.
Correct Answer: (B) 3350 × 10³ J
Solution:
Q = mL
Q = 10 × 335 × 10³
Q = 3350 × 10³ J
29. The far point of some persons will not be at infinity. Name the defect of the eye of such persons.
Correct Answer: (A) Near-sightedness
Solution:
In myopia, or near-sightedness, the far point is at a finite distance
instead of infinity. Therefore distant objects cannot be seen clearly.
30. Monomer of natural rubber is:
Correct Answer: (A) Cis-isoprene
Solution:
Natural rubber is cis-1,4-polyisoprene. Its monomer is isoprene.
31. A n-type semiconductor is made by adding which of the given impurity atom to silicon?
Correct Answer: (D) Arsenic
Solution:
Silicon is tetravalent. Arsenic is pentavalent and contributes one
extra free electron when added to silicon. Hence it forms an n-type
semiconductor.
32. An atom with high electronegativity has:
Correct Answer: (A) High ionisation enthalpy
Solution:
Highly electronegative atoms strongly attract electrons. They generally
have small atomic size and high ionisation enthalpy.
33. In which colour does a red flower appear in green light?
Correct Answer: (C) Dark
Solution:
A red flower reflects red light and absorbs other colours. Under green
light, there is no red light available for reflection, so the flower
appears dark.
34. Sulphide ores are usually concentrated by:
Correct Answer: (D) Froth flotation
Solution:
Froth flotation is the most common method for concentrating sulphide ores.
Ore particles attach to the froth and separate from the gangue.
35. 32 g of O₂ and 28 g of N₂ at STP occupy separately a volume of:
Correct Answer: (B) 22.4 L
Solution:
32 g O₂ = 1 mole and 28 g N₂ = 1 mole.
At STP, one mole of an ideal gas occupies 22.4 L.
Therefore, each gas occupies 22.4 L separately.
36. Find the amount of energy obtained when 1 kg matter is converted to energy.
Correct Answer: (A) 9 × 10¹⁶ J
Solution:
According to Einstein:
E = mc²
For m = 1 kg:
E = 1 × (3 × 10⁸)²
E = 9 × 10¹⁶ J
37. Give the IUPAC name of neopentane.
Correct Answer: (A) 2,2-dimethylpropane
Solution:
Neopentane has a central carbon atom attached to four methyl groups.
Its IUPAC name is 2,2-dimethylpropane.
38. Which law given below helps to find the direction of rotation of an armature of a DC motor?
Correct Answer: (D) Fleming’s Left Hand Rule
Solution:
Fleming’s Left Hand Rule determines the direction of force on a
current-carrying conductor placed in a magnetic field. It is therefore
used for finding the direction of rotation in a motor.
39. The reaction taking place in an atom bomb is:
Correct Answer: (B) Uncontrolled nuclear fission
Solution:
An atomic bomb involves an uncontrolled chain reaction of nuclear
fission, resulting in a very rapid release of nuclear energy.
40. An object which is immersed completely in a fluid experiences a buoyant force which is ______ of the fluid displaced by it.
Correct Answer: (B) Equal to the weight
Solution:
According to Archimedes’ principle, the buoyant force acting on an
immersed body is equal to the weight of the fluid displaced by it.
41. In the circuit given below, the effective resistance between A and B is 4 Ω. Find the resistance X.
Correct Answer: The supplied image appears to contain an inconsistency.
Solution:
From the visible circuit, the upper branch is:
4 Ω + 6 Ω = 10 Ω
The lower branch is:
X + 5 Ω
These two branches are parallel. Using the visible values and an
equivalent resistance of 4 Ω does not produce one of the printed
options exactly. Therefore, the original scan should be checked for
the unclear resistance value.
42. When a ray of light enters from air to glass obliquely, the refracted ray:
Correct Answer: (A) Deviates towards the normal
Solution:
Glass is optically denser than air. When light travels from a rarer
medium to a denser medium, it bends towards the normal.
43. Identify the odd one.
Correct Answer: (B) Assumption
Solution:
Assimilation, accommodation and equilibration are concepts associated
with Piaget’s cognitive development theory. Assumption is not one of
these processes.
44. Identify the correct sequence.
Correct Answer: (C) Terms → Facts → Concepts → Principles → Theories
Solution:
Scientific knowledge develops progressively from terms and facts to
concepts, principles and finally theories.
45. Zone of proximal development is the contribution of:
Correct Answer: (D) Vygotsky
Solution:
Lev Vygotsky introduced the concept of the Zone of Proximal Development
(ZPD), which describes the gap between what a learner can do independently
and what the learner can do with guidance.
46. Which among the following does not comprise in-service professional enrichment programme of teachers?
Correct Answer: (C) Staff meeting
Solution:
Refresher courses, workshops and conferences are professional development
activities. A routine staff meeting is not normally considered a formal
in-service professional enrichment programme.
47. Identify the statement which is LEAST applicable to improvised aids.
Correct Answer: (D) To show the expertise of the teacher
Solution:
Improvised teaching aids are mainly used to make teaching economical,
interesting and varied. Demonstrating the teacher’s expertise is not
their primary purpose.
48. If a Physics teacher purposefully compares the functioning of levers with the movements of the human body, then it is:
Correct Answer: (C) Systematic correlation
Solution:
The teacher deliberately establishes a planned relationship between
concepts from Physics and Biology. This purposeful interdisciplinary
relationship is systematic correlation.
49. If the concept of light is included in different grades by keeping the linkage and continuity, then it is:
Correct Answer: (C) Spiral approach
Solution:
In the spiral approach, the same concept is revisited at different
levels with increasing depth and complexity while maintaining continuity.
50. Which among the following is an intellectual or shrewd guess that is provisionally formulated to guide investigation?
Correct Answer: (A) Hypothesis
Solution:
A hypothesis is a tentative explanation or prediction that is formulated
before investigation and can be tested using evidence.
51. Identify Revised Bloom’s Taxonomy from among the following.
Correct Answer: (B)
Solution:
Revised Bloom’s Taxonomy consists of:
Remembering → Understanding → Applying → Analysing → Evaluating → Creating
52. Mills’ canons come under the category of:
Correct Answer: (A) Induction
Solution:
John Stuart Mill’s methods such as the Method of Agreement and Method
of Difference are methods of inductive reasoning.
53. If a student is ready to change his views in the light of authentic evidence, he/she has developed:
Correct Answer: (C) Scientific attitude
Solution:
Scientific attitude involves objectivity, open-mindedness and willingness
to modify conclusions when reliable evidence demands it.
54. The book entitled “From Classical to Quantum Mechanics” was authored by:
Correct Answer: (A) ECG Sudarshan
Solution:
The work “From Classical to Quantum Mechanics” is associated with
physicist E. C. G. Sudarshan.
55. Which among the following is NOT a process skill?
Correct Answer: (C) Recognising
Solution:
Observing, measuring and communicating are important science process
skills. Recognising is not generally included among the basic science
process skills.
56. Which among the following does NOT belong to Gagne’s hierarchy of learning?
Correct Answer: (D) Engaging
Solution:
Gagné’s hierarchy includes signal learning, stimulus-response learning,
chaining, verbal association, discrimination learning, concept learning,
rule learning and problem solving. Engaging is not a level in this hierarchy.
57. Identify the odd one.
Correct Answer: (D) Peg boards
Solution:
Charts, posters and flash cards are mainly visual display aids.
A peg board is a manipulative or three-dimensional teaching aid.
58. The principle of curriculum construction that enables learner to adjust with confronting situations is:
Correct Answer: (B) Forward looking principle
Solution:
The forward-looking principle prepares learners for future needs,
changing circumstances and new challenges.
59. Select the incorrect statement from the following.
Correct Answer: (C)
Solution:
Science fairs require considerable planning, organization and participation.
Therefore, stating that they require less systematic planning than a
science exhibition is incorrect.
60. Which among the following gives provision for self testing for students?
Correct Answer: (A) Workbook
Solution:
A workbook contains exercises and activities that allow students to
practise and check their own learning.
61. Which among the following is NOT an observable and measurable behavioral change?
Correct Answer: (D) Understanding
Solution:
Understanding is an internal cognitive process and cannot be directly
observed. Identifying, illustrating and justifying can be demonstrated
through observable performance.
62. If a teacher teaches the concept of metals by showing various metallic substances, then it comes under:
Correct Answer: (C) Inductive method
Solution:
The teacher begins with particular examples and moves towards a general
concept. Moving from specific examples to a general rule is inductive reasoning.
63. If a teacher uses the example of ripples in water to teach the concept of wave theory, then it is:
Correct Answer: (A) Analogy
Solution:
An analogy explains a new concept by comparing it with something
familiar. Water ripples are used as a familiar example to explain waves.
64. Which among the following is NOT a characteristic of a good textbook according to Vogel?
Correct Answer: (C) Publicity of the author
Solution:
A good textbook should have organized content, suitable illustrations
and good physical presentation. Publicity of the author is not a criterion
for textbook quality.
65. Identify the higher order question from among the following.
Correct Answer: (D) Compare rolling friction with that of sliding friction
Solution:
Higher-order questions require analysis, comparison, evaluation or reasoning.
Comparing two forms of friction requires analytical thinking.
66. Which among the following is not mandatory in a lesson plan?
Correct Answer: (D) Grouping technique
Solution:
Objectives, content analysis and learning experiences are important
components of lesson planning. Grouping technique is not compulsory
for every lesson.
67. Fill in the blanks: Lesson plan : Teaching :: Blueprint : ______
Correct Answer: (B) Achievement test
Solution:
A lesson plan provides a plan for teaching. Similarly, a blueprint
provides a framework for constructing an achievement test.
68. Scientific attitude can be least developed through:
Correct Answer: (C) Taking efforts for enhancing rote memorization
Solution:
Scientific attitude develops through observation, experimentation,
questioning and evidence-based thinking. Rote memorization does not
effectively develop scientific attitude.
69. “Science is the pursuit of truth in a truthful manner.” Identify the function of science implied here.
Correct Answer: (A) Moral function
Solution:
The statement emphasizes truthfulness, honesty and ethical behaviour.
Hence it represents the moral function of science.
70. Syntax is mainly associated with:
Correct Answer: (A) Models of teaching
Solution:
In models of teaching, syntax refers to the sequence and structure of
steps followed during the teaching-learning process.
71. Which among the following statements is LEAST related to Science?
Correct Answer: (B)
Solution:
Science is not exclusively the product of investigation. It involves
observation, experimentation, reasoning, explanation and communication.
72. Identify the statement which can be best considered as a concept.
Correct Answer: (C) Metals are mostly solids
Solution:
A concept is a generalized idea based on common characteristics of a
group. “Metals are mostly solids” is a generalization about metals.
73. In the circuit shown, determine the effective resistance between A and B.
Answer: The supplied scan has an apparent inconsistency in the circuit values.
Solution:
For resistors in series, their resistances are added.
For branches in parallel:
1/R = 1/R₁ + 1/R₂
The visible values in the supplied image do not give one of the
printed options exactly, so the original source should be checked
before publishing this particular answer.
74. Which principle explains the bending of light when it passes from air into glass?
Correct Answer: (B) Refraction
Solution:
When light passes from one transparent medium to another of different
optical density, its speed changes and its direction may change.
This phenomenon is called refraction.
75. What is the SI unit of electrical energy?
Correct Answer: (B) Joule
Solution:
Electrical energy is measured in joules in the SI system.
One joule is equal to one watt-second.
76. What is the SI unit of power?
Correct Answer: (C) Watt
Solution:
Power is the rate of doing work:
P = W/t
Its SI unit is watt (W).
77. What is the relation between frequency and time period?
Correct Answer: (B) f = 1/T
Solution:
Frequency is the number of oscillations per second, while time period
is the time taken for one complete oscillation. Hence they are reciprocals:
f = 1/T
78. What happens to the resistance of a metallic conductor when its temperature increases?
Correct Answer: (B) It increases
Solution:
In metals, an increase in temperature increases lattice vibrations.
Electrons experience more collisions, so the resistance increases.
79. What is the main difference between AC and DC?
Correct Answer: (A)
Solution:
Alternating current changes its magnitude and direction periodically.
Direct current flows essentially in one direction.
80. Which statement correctly describes direct current?
Correct Answer: (B) It flows in a single direction.
Solution:
Direct current (DC) is electric current that flows in one direction.
Batteries and cells are common sources of DC.