Pariksha SaathiPedagogy
CTET Science MCQ with Answers, Paper 2
353 practice questions on Science and its Pedagogy (Paper II) for CTET Paper II (Mathematics and Science), with answers; most also have an explanation or a worked solution. Try each one before you open its answer.
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Q.101
Which of the following can NEVER form an image that can be obtained on a screen?
- A A concave mirror
- B A convex lens
- C A convex mirror
- D A pinhole camera
Show answer
Correct answer: (C) A convex mirror
A convex mirror always forms an erect, smaller, virtual image, which cannot be caught on a screen. A concave mirror and a convex lens can form real, inverted images on a screen, and a pinhole camera forms its image on its screen.
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Q.102
In a plant, the vascular tissue that carries food from the leaves to other parts of the plant is:
- A Xylem
- B Root hairs
- C Stomata
- D Phloem
Show answer
Correct answer: (D) Phloem
Phloem transports the food prepared in the leaves to all parts of the plant. Xylem carries water and minerals upwards from the roots; root hairs absorb water, and stomata allow exchange of gases and loss of water vapour.
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Q.103
A tester shows that tap water conducts electricity, but distilled water hardly conducts at all. The reason is that:
- A Tap water has dissolved salts, while distilled water is free of them
- B Distilled water contains more salts, and these block the current
- C Water conducts only while it is flowing through metal pipes
- D Tap water is warmer, and only warm liquids conduct electricity
Show answer
Correct answer: (A) Tap water has dissolved salts, while distilled water is free of them
Pure (distilled) water is a poor conductor. Water from taps, hand pumps and wells contains dissolved salts, which make it a conductor; adding a little common salt to distilled water also makes it conduct.
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Q.104
Consider the following statements:
1. Jupiter is the largest planet of the solar system.
2. Saturn is less dense than water.
3. Mars has no natural satellite.
Which of the statements given above are correct?
- A 1 and 2 only
- B 1 and 3 only
- C 2 and 3 only
- D 1, 2 and 3
Show answer
Correct answer: (A) 1 and 2 only
Jupiter is the largest planet, and Saturn, with its beautiful rings, is less dense than water, so statements 1 and 2 are correct. Statement 3 is wrong: Mars, the red planet, has two small natural satellites.
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Q.105
A Class 6 class includes a child with visual impairment. During a lesson on the parts of a flower, the teacher can best include her by:
- A Excusing her from the lesson and giving her free time instead
- B Asking her only to memorise the names of the parts of a flower from an audio recording
- C Giving her the same worksheet as others, in regular print
- D Letting her feel real flowers and tactile models while classmates describe them
Show answer
Correct answer: (D) Letting her feel real flowers and tactile models while classmates describe them
Children with visual impairment can learn science well through touch, smell, hearing and verbal description. Real specimens, tactile models and peer description let her take part in the same lesson instead of being left out.
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Q.106
Tadpoles kept in water that lacks enough iodine may fail to grow into adult frogs. Why?
- A Iodine is needed to make insulin, which controls the growth of the gills
- B Iodine dissolved in pond water is the main food of tadpoles
- C Iodine is needed to make thyroxine, which controls metamorphosis
- D Iodine is needed for the gills of tadpoles to absorb oxygen
Show answer
Correct answer: (C) Iodine is needed to make thyroxine, which controls metamorphosis
In frogs the change from tadpole to adult (metamorphosis) is controlled by thyroxine, a hormone made by the thyroid gland, and making thyroxine requires iodine. Without enough iodine in the water, the tadpoles cannot become adults.
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Q.107
During group practical work, a teacher notices that in every group the boys handle the apparatus while the girls only write the records. The teacher should:
- A Rotate roles so that every child, girl or boy, handles the apparatus and records observations
- B Continue, since the groups have divided the work by themselves
- C Give girls theory questions instead of practical work
- D Make separate groups for girls and boys
Show answer
Correct answer: (A) Rotate roles so that every child, girl or boy, handles the apparatus and records observations
Gender stereotypes in science are reinforced when girls are kept away from hands-on work. Rotating roles ensures equal opportunity to develop psychomotor and process skills and challenges the stereotype.
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Q.108
Assertion (A): Women and children usually have a higher-pitched voice than men.
Reason (R): The loudness of a sound depends on the amplitude of vibration.
- A Both A and R are true, and R is the correct explanation of A
- B Both A and R are true, but R is not the correct explanation of A
- C A is true, but R is false
- D A is false, but R is true
Show answer
Correct answer: (B) Both A and R are true, but R is not the correct explanation of A
Both statements are true, but pitch depends on frequency, not on amplitude. Women and children have shorter vocal cords, which vibrate with a higher frequency, so R, which is about loudness, does not explain A.
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Q.109
After fertilisation in a flowering plant, the ovary and the ovules develop, respectively, into:
- A Seeds and fruit
- B Fruit and seeds
- C Embryo and pollen grains
- D Seeds and embryo
Show answer
Correct answer: (B) Fruit and seeds
After fertilisation the ovary grows into the fruit and the ovules develop into seeds; inside each ovule the zygote develops into an embryo.
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Q.110
Why do we see different shapes (phases) of the Moon during a month?
- A Different parts of the Moon's sunlit half face the Earth as the Moon revolves
- B The Earth's shadow covers a different part of the Moon each night
- C The light given out by the Moon itself rises and falls during the month
- D Clouds in the sky hide a different part of the Moon each night
Show answer
Correct answer: (A) Different parts of the Moon's sunlit half face the Earth as the Moon revolves
The Sun always lights up one half of the Moon. As the Moon revolves around the Earth, we see different portions of this lit half, which gives the phases; the Earth's shadow falls on the Moon only during a lunar eclipse.
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Q.111
A student can recite the definition of photosynthesis word for word but cannot explain why a plant kept in a dark cupboard for many days becomes pale and weak. This mainly shows that:
- A The question asked was outside the syllabus
- B The student has a very weak memory
- C The student has learnt by rote without conceptual understanding
- D The definition that was taught to the student was itself scientifically wrong
Show answer
Correct answer: (C) The student has learnt by rote without conceptual understanding
Reproducing a definition but being unable to apply it to a new situation is a sign of rote learning. NCF 2005 asks that learning move away from rote methods toward understanding that can be used in real situations.
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Q.112
Consider the following statements about rusting:
1. For iron to rust, the presence of both oxygen and water (or water vapour) is essential.
2. Iron objects rust faster in a dry desert than in a humid coastal area.
Which of the statements given above is/are correct?
- A Only 1
- B Only 2
- C Both 1 and 2
- D Neither 1 nor 2
Show answer
Correct answer: (A) Only 1
Rusting needs both oxygen and water; if either is absent, iron does not rust. The more moisture in the air, the faster the rusting, so iron rusts faster in coastal areas than in deserts and statement 2 is wrong.
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Q.113
Match the plant disease in List I with the type of microorganism that causes it (List II).
List I: A. Citrus canker B. Rust of wheat C. Yellow vein mosaic of bhindi (okra)
List II: 1. Bacterium 2. Virus 3. Fungus
- A A-1, B-3, C-2
- B A-3, B-1, C-2
- C A-2, B-3, C-1
- D A-1, B-2, C-3
Show answer
Correct answer: (A) A-1, B-3, C-2
Citrus canker is a bacterial disease spread through air, rust of wheat is caused by fungi spread through air and seeds, and yellow vein mosaic of bhindi is a viral disease spread by insects.
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Q.114
When you look through a sheet of oiled paper, you can see objects behind it, but not clearly. Such a material is called:
- A Transparent
- B Translucent
- C Opaque
- D Lustrous
Show answer
Correct answer: (B) Translucent
Materials through which objects can be seen, but not clearly, are translucent; oiled paper and frosted glass are examples. Through transparent materials objects are seen clearly, and through opaque ones not at all.
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Q.115
One of NCERT's learning outcomes for upper primary science is that the learner 'conducts simple investigations to seek answers to queries'. Which classroom evidence best shows a Class 7 learner achieving it?
- A She copies the class notes on acids and bases neatly into her notebook and decorates them
- B She tests whether coloured flower extracts change colour in lemon juice and soap solution
- C She writes the textbook definition of an indicator correctly from memory, word for word
- D She lists five acids that are found in common foods
Show answer
Correct answer: (B) She tests whether coloured flower extracts change colour in lemon juice and soap solution
Planning and carrying out a test to find the answer to a question is direct evidence of this outcome. Recalling a definition, copying notes or listing names shows memory, not investigation.
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Q.116
Seeing water drops on the outside of a glass of ice-cold water, a student says the water has seeped out through the glass. Which activity best challenges this idea?
- A Using ice water mixed with food colour and checking if the outside drops are coloured
- B Reading out the definition of condensation from the textbook and asking them to learn it
- C Asking the student to wipe the glass dry and move on
- D Telling the student that glass has extremely tiny holes
Show answer
Correct answer: (A) Using ice water mixed with food colour and checking if the outside drops are coloured
If the water came through the glass, the drops outside would be coloured. Colourless drops show that they come from water vapour in the air condensing on the cold surface, which the student can see for himself.
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Q.117
While preparing dilute sulphuric acid in the school laboratory, the safe procedure is to:
- A Add water to the concentrated acid quickly
- B Add the concentrated acid slowly to water with constant stirring
- C Mix them in any order since the result is the same
- D Heat the acid first and then add water
Show answer
Correct answer: (B) Add the concentrated acid slowly to water with constant stirring
Dilution of concentrated acid is strongly exothermic. Adding water to acid can make the small amount of water boil and spatter acid; adding acid slowly to a larger volume of water absorbs the heat safely.
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Q.118
In a science curriculum, children only read and memorise finished conclusions and never observe, hypothesise or test anything themselves. Which NCF 2005 validity criterion does it fail most clearly?
- A Historical validity
- B Content validity
- C Cognitive validity
- D Process validity
Show answer
Correct answer: (D) Process validity
Process validity requires that the curriculum engage learners in the methods and processes that lead to the generation and validation of scientific knowledge, nurturing curiosity and creativity. The content may still be correct, but the child never experiences how science works.
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Q.119
A girl stands 2 m in front of a plane mirror. What is the distance between her and her image?
- A 2 m
- B 1 m
- C 8 m
- D 4 m
Show answer
Correct answer: (D) 4 m
A plane mirror forms the image as far behind the mirror as the object is in front of it. The image is 2 m behind the mirror, so it is 2 + 2 = 4 m from the girl.
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Q.120
Before a lesson on light, a teacher asks, 'How are we able to see this book on the table?' and writes every answer on the board without correcting any. The main purpose is to:
- A Bring out students' existing ideas so that teaching can start from them
- B Find out which students deserve punishment for giving wrong answers in class
- C Check how well students have memorised the textbook
- D Fill up the time before the actual lesson begins
Show answer
Correct answer: (A) Bring out students' existing ideas so that teaching can start from them
Constructivist teaching begins by eliciting what learners already think. Knowing children's prior ideas, including alternative conceptions, lets the teacher plan experiences that build on or challenge them.
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Q.121
Tests show that the soil of a farmer's field is too basic. To neutralise it, he should add:
- A Quicklime (calcium oxide)
- B Slaked lime (calcium hydroxide)
- C Organic matter such as compost
- D Baking soda (sodium hydrogencarbonate)
Show answer
Correct answer: (C) Organic matter such as compost
Organic matter releases acids that neutralise the basic nature of the soil. Quicklime and slaked lime are bases used for soil that is too acidic, and baking soda is also basic.
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Q.122
After puberty, many boys have a protruding part in the front of the throat called the 'Adam's apple'. It is:
- A The enlarged voice box (larynx)
- B A swelling of the thyroid gland
- C The upper end of the food pipe
- D A swollen gland of the neck
Show answer
Correct answer: (A) The enlarged voice box (larynx)
At puberty the voice box (larynx) grows; in boys it becomes large enough to be seen as a protruding part of the throat, the Adam's apple, and the voice becomes deeper. A swelling of the thyroid gland in the neck is goitre.
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Q.123
Why is loamy soil considered the best topsoil for growing most plants?
- A It is made only of large sand particles, so all the water drains away quickly
- B It mixes sand, clay and silt with humus, holding enough water and air
- C It is made only of fine clay particles, so that no air can enter it
- D It contains no humus, so harmful microorganisms cannot live in it
Show answer
Correct answer: (B) It mixes sand, clay and silt with humus, holding enough water and air
Loamy soil is a mixture of sand, clay and silt, and it also contains humus. It has the right water-holding capacity and enough air for roots, which makes it good for growing most plants.
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Q.124
Before storing freshly harvested grain, farmers dry it well in the sun. The main purpose is to:
- A Add vitamins to the grain from the sunlight
- B Make the grain heavier so that it fetches a better price
- C Reduce moisture so that pests, bacteria and fungi do not spoil it
- D Separate the chaff from the grain seeds
Show answer
Correct answer: (C) Reduce moisture so that pests, bacteria and fungi do not spoil it
Freshly harvested grains contain more moisture and, if stored without drying, may be spoilt by insect pests, bacteria and fungi and lose their ability to germinate. Drying reduces the moisture and prevents this.
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Q.125
The NCF 2005 Position Paper on Teaching of Science lists validity criteria for a good science curriculum. The criterion that the curriculum should convey significant and scientifically correct content is called:
- A Content validity
- B Process validity
- C Cognitive validity
- D Ethical validity
Show answer
Correct answer: (A) Content validity
Content validity requires that the curriculum conveys significant and correct scientific content. Cognitive validity, a common distractor, refers to matching the content and process to the child's cognitive development level.
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Q.126
For which of the following would a computer simulation or animation be MOST appropriate in a Class 8 science lesson?
- A Finding out which materials around us are attracted by a magnet
- B Showing how particles move in solids, liquids and gases
- C Testing whether seeds need water to germinate
- D Observing the parts of a flower
Show answer
Correct answer: (B) Showing how particles move in solids, liquids and gases
Simulations are most valuable for what learners cannot see or do directly, such as invisible particles, very large or very slow processes, or unsafe experiments. Magnets, flowers and germination can be studied hands-on, which a simulation should not replace.
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Q.127
Match the animal (List I) with the main form in which it excretes its nitrogenous waste (List II):
A. Fish
B. Birds and lizards
C. Humans
1. Urea
2. Uric acid
3. Ammonia
- A A-1, B-2, C-3
- B A-3, B-2, C-1
- C A-3, B-1, C-2
- D A-2, B-3, C-1
Show answer
Correct answer: (B) A-3, B-2, C-1
Aquatic animals such as fish excrete waste as ammonia, which dissolves directly in water. Birds, lizards and snakes excrete a semi-solid, white compound, uric acid, and the main waste in humans is urea.
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Q.128
According to the conceptual change model of Posner and his colleagues, which of the following is one of the conditions for a learner to give up an existing idea in favour of a scientific one?
- A The new idea must be repeated to the learner many times
- B The learner must become dissatisfied with the existing idea
- C An authority must declare the old idea to be wrong
- D The learner must memorise the definition of the new idea word for word
Show answer
Correct answer: (B) The learner must become dissatisfied with the existing idea
The model states that learners must be dissatisfied with their existing conception and that the new one must be intelligible, plausible and fruitful. That is why teachers create situations in which the old idea fails to explain what is observed.
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Q.129
In an activity, 200 mL of water is poured on a soil sample, and it takes 40 minutes for all of it to percolate through. What is the percolation rate of this soil?
- A 0.2 mL/min
- B 5 mL/min
- C 240 mL/min
- D 8000 mL/min
Show answer
Correct answer: (B) 5 mL/min
Percolation rate (mL/min) = amount of water (mL) ÷ percolation time (min) = 200 ÷ 40 = 5 mL/min. Dividing the time by the volume gives 0.2, which turns the formula upside down.
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Q.130
Consider the following statements about roughage (dietary fibre):
1. Roughage gives the body a large amount of energy.
2. Roughage helps the body get rid of undigested food.
Which of the statements given above is/are correct?
- A Only 1
- B Only 2
- C Both 1 and 2
- D Neither 1 nor 2
Show answer
Correct answer: (B) Only 2
Roughage gives the body little or no energy and, as NCERT puts it, provides no nutrient, but it adds bulk to the food and helps the body get rid of undigested food. Whole grains, pulses, fresh fruits and vegetables are its main sources.
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Q.131
Excess fertiliser washed from fields into a pond leads to heavy growth of algae. Later, many fish in the pond die. Why?
- A The algae release poisonous carbon monoxide gas into the water
- B The fertiliser makes the water so cold that fish cannot survive
- C Decay of dead algae by decomposers uses up the dissolved oxygen
- D The algae eat up all the food that was meant for the fish
Show answer
Correct answer: (C) Decay of dead algae by decomposers uses up the dissolved oxygen
Fertilisers act as nutrients for algae, which grow abundantly. When the algae die, decomposers such as bacteria break them down and use up much of the oxygen dissolved in the water, so fish and other aquatic organisms die.
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Q.132
Which of the following is NOT a component of scientific attitude?
- A Open-mindedness
- B Curiosity
- C Suspended judgement until sufficient evidence is available
- D Accepting statements on the basis of authority without evidence
Show answer
Correct answer: (D) Accepting statements on the basis of authority without evidence
Scientific attitude includes curiosity, open-mindedness, objectivity, suspended judgement and respect for evidence. Accepting claims merely because of the authority of the person making them is the opposite of scientific attitude.
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Q.133
The main purpose of setting up a biosphere reserve is to:
- A Keep wild animals in cages so that visitors can see them closely
- B Grow a single kind of tree on a large scale for timber
- C Allow hunting of wild animals under a government licence
- D Conserve biodiversity and the traditional life of local people
Show answer
Correct answer: (D) Conserve biodiversity and the traditional life of local people
A biosphere reserve is a large protected area meant to conserve the biodiversity of a region, its plants, animals and microorganisms, together with the traditional life of the people living there. Keeping animals in cages describes a zoo.
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Q.134
CNG is being promoted in place of petrol and diesel for vehicles in cities mainly because it:
- A Is an inexhaustible resource that will never run out
- B Produces no carbon dioxide at all when it burns
- C Burns cleanly and produces very small amounts of harmful products
- D Is a liquid that can be stored in any open container
Show answer
Correct answer: (C) Burns cleanly and produces very small amounts of harmful products
CNG is a cleaner fuel that produces very small amounts of harmful products. It is still a fossil fuel and therefore exhaustible, and like other carbon fuels it gives carbon dioxide on burning.
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Q.135
Jams and jellies are preserved by adding a large amount of sugar. Sugar prevents spoilage mainly because it:
- A Makes the food acidic, like the vinegar in pickles
- B Kills all microorganisms by producing heat
- C Reduces the moisture content, which checks the growth of bacteria
- D Forms an airtight layer that keeps out all oxygen
Show answer
Correct answer: (C) Reduces the moisture content, which checks the growth of bacteria
Sugar reduces the moisture content of the food, and this inhibits the growth of the bacteria that spoil it. Vinegar and oil preserve pickles in a different way, by making conditions unsuitable for bacteria.
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Q.136
Which two gases together make up about 99 per cent of the air around us?
- A Nitrogen and oxygen
- B Oxygen and carbon dioxide
- C Nitrogen and carbon dioxide
- D Oxygen and water vapour
Show answer
Correct answer: (A) Nitrogen and oxygen
Nitrogen (about 78 per cent) and oxygen (about 21 per cent) together make up about 99 per cent of air. Carbon dioxide, water vapour, argon and other gases form only a small part.
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Q.137
A diagnostic test shows that several students think water evaporates only when it boils. For remedial teaching, the teacher should:
- A Repeat the same lecture on evaporation, but more slowly and loudly than before
- B Let them watch wet cloths dry at room temperature and discuss what they see
- C Ask them to write the definition of evaporation twenty times
- D Seat them separately from the rest of the class as weak students who need watching
Show answer
Correct answer: (B) Let them watch wet cloths dry at room temperature and discuss what they see
Remedial teaching targets the specific difficulty found by diagnosis, usually through a different and more concrete approach. Seeing water disappear without heating directly challenges the idea that evaporation needs boiling.
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Q.138
A child can move her arm in a full circle at the shoulder, but at the elbow she can move her forearm only back and forth in one direction. The joints at the shoulder and the elbow are, respectively:
- A Hinge joint; ball and socket joint
- B Pivotal joint; hinge joint
- C Ball and socket joint; pivotal joint
- D Ball and socket joint; hinge joint
Show answer
Correct answer: (D) Ball and socket joint; hinge joint
A ball and socket joint, as at the shoulder and the hip, allows movement in all directions. A hinge joint, as at the elbow and the knee, allows back-and-forth movement in one direction only, like the hinge of a door.
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Q.139
'Scientific literacy' as an aim of school science education is best described as:
- A The ability to read science textbooks fluently
- B Memory of important scientific formulae and definitions
- C Training every child to become a professional scientist
- D Using scientific knowledge and ways of thinking to take informed decisions in everyday life
Show answer
Correct answer: (D) Using scientific knowledge and ways of thinking to take informed decisions in everyday life
Scientific literacy is the capacity of an ordinary citizen to understand and use scientific ideas and evidence in daily life and public issues, such as health, environment and technology, not professional expertise.
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Q.140
Assertion (A): In a lichen, a fungus and an alga live together and both benefit.
Reason (R): The fungus prepares food by photosynthesis and gives it to the alga.
Choose the correct option.
- A Both A and R are true, and R is the correct explanation of A
- B Both A and R are true, but R is not the correct explanation of A
- C A is true, but R is false
- D A is false, but R is true
Show answer
Correct answer: (C) A is true, but R is false
A lichen is a symbiotic association, so A is true. R is false: the alga, which has chlorophyll, makes the food, while the fungus provides shelter, water and minerals.
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Q.141
Assertion (A): A concept map drawn by a student can be used to assess how well the student understands the relationships among the ideas of a topic.
Reason (R): In a concept map, concepts are joined by labelled links that state how they are related.
Choose the correct option.
- A Both A and R are true, and R is the correct explanation of A
- B Both A and R are true, but R is not the correct explanation of A
- C A is true, but R is false
- D A is false, but R is true
Show answer
Correct answer: (A) Both A and R are true, and R is the correct explanation of A
Both are true, and R explains A: because each link must state a relationship, the map shows which connections the student has understood, missed or got wrong. This makes concept maps useful for formative and diagnostic assessment.
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Q.142
Students look through a set of objects one by one and sort them into transparent, translucent and opaque groups. Which process skill are they mainly using?
- A Controlling variables
- B Hypothesising
- C Classifying
- D Predicting
Show answer
Correct answer: (C) Classifying
Classifying means grouping objects or events on the basis of shared observable properties, here how much light passes through them. Predicting and hypothesising concern what will happen or why, not grouping.
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Q.143
Which is the most suitable way to measure the length of a curved line drawn on a sheet of paper?
- A Measure the straight gap between the two ends of the curve and use that as its length
- B Count how many times the curve changes its direction along the way
- C Hold a rigid metre scale over the curve and read the length off it directly
- D Lay a thread along the curve, mark its ends, then straighten it and measure it
Show answer
Correct answer: (D) Lay a thread along the curve, mark its ends, then straighten it and measure it
A rigid scale cannot follow a curve, but a thread can. Once the thread is straightened, the marked length equals the length of the curve; the straight distance between the ends is always shorter.
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Q.144
A teacher plans a visit to a nearby pond to study the organisms living there. Which plan will make the visit most useful for learning?
- A Ask students only to enjoy the outing and not to note down anything
- B Take the students without any preparation so that everything at the pond comes as a surprise
- C Show pictures of a pond in the classroom instead of making the visit
- D Discuss questions and an observation sheet before the visit, and hold a discussion after it
Show answer
Correct answer: (D) Discuss questions and an observation sheet before the visit, and hold a discussion after it
A field trip works best in three stages: preparation (purpose, questions, observation sheets), guided observation during the visit, and follow-up (discussion, reports, display). Without these it becomes an outing rather than a learning experience.
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Q.145
Consider the following statements about safety during lightning:
1. A car or bus with its windows and doors shut is a safe place.
2. During a thunderstorm it is safe to keep using a corded telephone and plugged-in electrical appliances.
Which of the statements given above is/are correct?
- A Only 1
- B Only 2
- C Both 1 and 2
- D Neither 1 nor 2
Show answer
Correct answer: (A) Only 1
Statement 1 is right: a closed car or bus is a safe place, though open vehicles such as motorbikes and tractors are not. Statement 2 is wrong: telephone cords and electrical wires should not be touched, and appliances such as computers and TVs should be unplugged.
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Q.146
A potted plant that is watered far too much, so that its soil stays waterlogged, may wilt and die. The main reason is that:
- A Its leaves can no longer carry out transpiration
- B The water washes away the chlorophyll of its leaves
- C Its roots absorb too many minerals from the soil
- D Its roots do not get enough air for respiration
Show answer
Correct answer: (D) Its roots do not get enough air for respiration
Roots take in oxygen from the air present in the spaces between soil particles. When the soil is waterlogged these spaces fill with water, so the roots cannot get air for respiration and the plant may die.
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Q.147
A clinical thermometer usually reads temperatures from:
- A -10 °C to 110 °C
- B 35 °C to 42 °C
- C 0 °C to 100 °C
- D 37 °C to 100 °C
Show answer
Correct answer: (B) 35 °C to 42 °C
A clinical thermometer measures human body temperature, which normally stays within this narrow range. A laboratory thermometer usually has a range of -10 °C to 110 °C.
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Q.148
Assertion (A): Light falling on a rough surface such as cardboard is reflected in many different directions.
Reason (R): The laws of reflection do not hold for rough surfaces.
- A Both A and R are true, and R is the correct explanation of A
- B Both A and R are true, but R is not the correct explanation of A
- C A is true, but R is false
- D A is false, but R is true
Show answer
Correct answer: (C) A is true, but R is false
A is true: this is diffused or irregular reflection. R is false: the laws of reflection hold at every point of a rough surface, but because the surface is uneven the normals point in different directions, so the reflected rays scatter.
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Q.149
Consider the following statements about assessing process skills in science:
1. A practical test that only checks whether the final reading matches the expected value fully assesses process skills.
2. Process skills such as predicting and inferring cannot be assessed through written items.
Which of the statements is/are correct?
- A Only 1
- B Only 2
- C Both 1 and 2
- D Neither 1 nor 2
Show answer
Correct answer: (D) Neither 1 nor 2
Statement 1 is wrong because checking only the final answer ignores how the student planned, measured and recorded. Statement 2 is wrong because well-designed written items, for example ones that give data and ask for a prediction or inference, can assess these skills.
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Q.150
Consider the following statements about saprotrophs such as mushrooms and bread mould:
1. They secrete digestive juices on dead and decaying matter and absorb the nutrients from the solution formed.
2. They make their own food by photosynthesis using sunlight.
Which of the statements given above is/are correct?
- A Only 1
- B Only 2
- C Both 1 and 2
- D Neither 1 nor 2
Show answer
Correct answer: (A) Only 1
Saprotrophs convert dead and decaying matter into a solution with their digestive juices and absorb the nutrients from it. They have no chlorophyll and cannot photosynthesise, so statement 2 is wrong.
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