1. Burning biomass for energy does not release
1. sulphur
2. mercury
3. nitrogen
Select the correct answer using the codes given below.
a) 1 and 2 only
b) 2 only
c) 2 and 3 only
d) 1, 2 and 3
Answer & Explanation
a) 1 and 2 only. Unlike the burning of coal, which releases sulphur and mercury, biomass burning does not release them. It however releases nitrogen contained within the biomass.
2. Extra Vehicular Activity (EVA) is related to
a) racing and sports car driving.
b) manoeuvre outside military aircrafts.
c) works done outside spacecrafts
d) underwater maintenance work of large ships.
Answer & Explanation
c) works done outside spacecrafts. EVA is any activity performed by a pressure-suited crewmember in unpressurized or space environments. EVA begins with depressurization of the airlock or space module, and ends with repressurization of the space module or airlock after crewmember ingress. You might have watched the movie Gravity.
3. The cell wall is present in
1. bacteria
2. blue-green algae
3. plants
Select the correct answer using the codes given below.
a) 1 and 3 only
b) 2 and 3 only
c) 3 only
d) 1, 2 and 3
Answer & Explanation
d) 1, 2 and 3. All three have cell walls. Plants and blue-green algae are well known to possess cell wall. Bacteria also have cell walls. Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids. In contrast, Gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins.
4. Consider a body at temperature of 100 units kept in a room with room temperature 20 units.
Event A : The temperature of the body decreased from 100 to 60.
Event B : The temperature of the body decreased from 60 to 20.
Which of the following is true?
a) Time taken for A is more than that for B.
b) Time taken for A is less than that for B.
c) Both A and B will take equal time.
d) Data is insufficient to compare time taken.
Answer & Explanation
b) Time taken for A is less than that for B. The question is based on Newton’s law of cooling. Newton’s Law of Cooling states that the rate of change of the temperature of an object is proportional to the difference between its own temperature and the ambient temperature (i.e. the temperature of its surroundings). So, A will take less time than B.
5. Assertion (A) – Most satellite TV antenna in India face south, south east or south-west.
Reason (R) – TV transmission satellite mostly uses a geostationary orbit.
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 a correct explanation of A
c) A is true but R is false
d) A is false but R is true
Answer & Explanation
a) Both A and R are true and R is the correct explanation of A. TV transmission satellite is in a geostationary orbit. Geostationary orbits can only be accomplished with equatorial orbits, and since India is in the northern hemisphere this means the satellite will always be in south direction. Very few communication satellites use polar orbits, or any orbit inclined out of the equatorial plane for that matter, to prevent the need for constant reaming of the receiver dish.
6. With reference to pesticides and insecticides, consider the following statements:
1. Both pesticides and insecticides kill by poisoning, suffocating or paralyzing.
2. Pesticides are a subgroup of insecticides that are specifically used for killing pests.
Which of the statements given above is/are correct?
a) 1 only
b) 2 only
c) Both 1 and 2
d) Neither 1 nor 2
Answer & Explanation
a) 1 only. The difference between a pesticide and insecticide lies in the different function each performs. A pesticide is a chemical substance that is used to kill, control, or repel pests, including mammals, fish, and insects. As the name implies, an insecticide affects only insects. This means that an insecticide is a subgroup of pesticides. Both pesticides and insecticides kill by poisoning, suffocating, or paralyzing.
7. With reference to sound waves, consider the following statements:
1. Sound waves can undergo diffraction and this phenomenon is used in auditoriums to provide better hearing experience.
2. It is because of diffraction that sound can be heard around corners even though sound travel in a straight line.
Which of the statements given above is/are correct?
a) 1 only
b) 2 only
c) Both 1 and 2
d) Neither 1 nor 2
Answer & Explanation
b) 2 only. Sound waves can undergo interference and this phenomenon is used in auditoriums to provide better hearing experience. It is because of diffraction that sound can be heard around corners even though sound travel in a straight line. In auditoriums, destructive interference between sound from the stage and sound reflected from other parts of the hall can create dead spots in which both volume and clarity of sound are poor. Such interference can be reduced by use of sound-absorbing materials on reflecting surfaces. On the other hand, interference can improve an auditorium’s acoustical qualities. This is done by arranging the reflecting surfaces in such a way that the level of sound is actually increased in the area in which the audience sits. When sound waves pass around an obstacle or through an opening in an obstacle, the edge of the obstacle or the opening acts as a secondary sound source, sending out waves of the same frequency and wavelength (but of lower intensity) as the original source. The spreading out of sound waves from the secondary source is called diffraction. Because of this phenomenon, sound can be heard around corners despite the fact that sound waves generally travel in a straight line.
8. Ammeter and Voltmeter are used to measure current and voltage respectively. Which of the following is true about them?
a) Ammeter is connected in series while voltmeter is connected in parallel.
b) Ammeter is connected in parallel while voltmeter is connected in parallel.
c) Both ammeter and voltmeter are connected in series.
d) Both ammeter and voltmeter are connected in parallel.
Answer & Explanation
a) Ammeter is connected in series while voltmeter is connected in parallel. A simple Class 10 science question.
9. There are four fundamental forces in the universe.
1. electromagnetic force.
2. gravitational force.
3. strong nuclear force.
4. weak nuclear force.
The correct order of these forces from strongest to weakest is
a) 2 3 4 1
b) 2 1 3 4
c) 1 3 4 2
d) 3 1 4 2
Answer & Explanation
d) 3 1 4 2. Gravitational force is the weakest among the fundamental forces. There are four fundamental forces (that we know of) in our universe: Strong Nuclear, Electromagnetic, Weak Nuclear and Gravitational. The strongest one is the Strong Nuclear force, which is responsible for keeping the nuclei of atoms together. About one hundred times weaker than the strong nuclear force is the electromagnetic one. This is the strongest force that we experience in our everyday lives. In fact, whenever we touch anything we experience the Electromagnetic force. The electrons in our skin repel electrons in whatever we touch through this force. The Weak Nuclear force is the one responsible for most decays of particles and nuclei – which is where radioactivity comes from. This force is about 10 billion times weaker than the Electromagnetic force. The weakest of all is the Gravitational force. In fact, Gravitational force is 10 thousand billion billion billion billion times weaker than the Electromagnetic force.
10. A virtual image can be formed by
1. concave mirror.
2. concave lens.
3. convex mirror.
4. convex lens
5. plane mirror
Select the correct answer using the codes given below.
a) 1, 2 and 5 only
b) 1, 4 and 5 only
c) 2 , 3 and 5 only
d) 1, 2, 3, 4 and 5
Answer & Explanation
d) 1, 2, 3, 4 and 5 All of these can form a virtual image. We studied these in class 8 and class 10. A virtual image is formed at the position where the paths of the principal rays cross when projected backward from their paths beyond the lens.
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