Pre 2014

1. Which of the following is/are the example/examples of chemical change?

1. Crystallization of sodium chloride
2. Melting of ice
3. Souring of milk

Select the correct answer using the code given below.

1. 1 and 2 only
2. 3 only
3. 1, 2 and 3
4. None

• 1 is crystallisation, so only physical form is changing not chemical
• Same with melting of ice h20 remains h20
• Souring of milk, chemical Composition changes as there’s acidification

2. Consider the following diseases

1. Diphtheria
2. Chickenpox
3. Smallpox

Which of the above diseases has/have been eradicated in India?

1. 1 and 2 only
2. 3 only
3. 1, 2 and 3
4. None

• Small pox everyone knows
• Chickenpox is an innocuous disease. Many of you may have contacted chicken pox during childhood
• Diphtheria vaccine aaj bhi DPT. Don’t say polio has been eradicated but uski vaccine bhi so funda bekar

3. Consider the following pairs :

Which of the pairs given above is/are correctly matched?

1. 1 and 2 only
2. 3 only
3. 1, 2 and 3
4. None

• 7th std science
• Vitamin A – night blindness
• C – scurvy
• D – rickets
• B1 – vetiver
• b3 – niacin – pallegra

4. In addition to fingerprint scanning, which of the following can be used in the biometric identification of a person?

1. Iris scanning
2. Retinal scanning
3. Voice recognition

Select the correct answer using the code given below.

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

• Common sense
• All are unique. All can be used

5. Which of the following pair is/are correctly matched?

Select the correct answer using the code given below.

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

• Cassini – Saturn very famous
• Learn about recent missions of NASA and ISRO

Pre 2013

1. Which of the following diseases can be transmitted from one person to another through tattooing?

1. Chikungunya
2. Hepatitis B
3. HIV-AIDS

Select the correct answer using the codes given below.

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

• Tattooing ie disease due to needle I. E blood
• Chikungunya we know is due to mosquito bite
• Eliminate it and reach the answer
• Hepatitis b and hiv are due to blood transfusion among other things

2. Consider the following minerals

1. Calcium
2. Iron
3. Sodium

Which of the minerals given above is/are required by human body for the contraction of muscles?

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

• Calcium is necessary for muscle contraction
• Sodium for transmission of impulse

3. Which of the following statements is / are correct?

1. Viruses lack enzymes necessary for the generation of energy.
2. Viruses can be cultured in any synthetic medium.
3. Viruses are transmitted from one organism to another by biological vectors only.

Select the correct answer using the codes given below.

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

• 2 is incorrect. Virus can not be cultured in any synthetic medium. Any is red flag.
• Similarly only is red flag in statement 3. Pause and think of other vectors

4. Recombinant DNA technology (Genetic Engineering) allows genes to be transferred

1. across different species of plants
2. from animals to plants
3. from microorganisms to higher organisms

Select the correct answer using the codes given below.

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

• Simple
• Can be transferred from anywhere to anywhere

5. Improper handling and storage of cereal grains and oilseeds result in the production of toxins known as aflatoxins which are not generally destroyed by normal cooking process. Aflatoxins are produced by

1. bacteria
2. protozoa
3. moulds
4. viruses

Fungus/ mould. Aspergillus Flavis

6  Fruits stored in a cold chamber exhibit longer storage life because

1. exposure to sunlight is prevented
2. concentration dioxide in the is increased of carbon environment
3. rate of respiration is decreased
4. there is an increase in humidity

• For longer shelf life, metabolic rate is to be reduced
• Decreased rate of respiration helps in that
• Increase humidity, high co2, exposure to sunlight is crap. It can be achieved in other ways also without needing cold chamber

7. Many transplanted seedlings do not grow because

1. the new soil does not contain favorable minerals
2. most of the root hairs grip the new soil too hard
3. most of the root hairs are lost during transplantation
4. leaves get damaged during transplantation

• 1 is crap. We can artificially add minerals to the new soil. It has to be about transplanted plant
• 2nd – why would it occur? No idea
• 3rd is very plausible. And loss of root hairs will prevent growth

8. Which of the following leaf modifications occurs/occur in desert areas to inhibit water loss?

1. Hard and waxy leaves
2. Tiny leaves or no leaves
3. Thorns instead of leaves

Select the correct answer using the codes given below.

1. 1 and 2 only
2. 2 only
3. 1 and 3 only
4. 1, 2 and 3

NCERT ecological portion or common sense

9. Ball bearings are used in bicycles, cars, etc.because

1. The actual area of contact between the wheel and axle is increased
2. The effective area of contact between the wheel and axle is increased
3. The effective area of contact between the wheel and axle is reduced
4. None of the statements is correct

• It is to reduce friction
• Less effective area of contact, less friction force
• In any case b and c are contradictory, one has to be true unless you think it has no relations with effective area

10. Consider the following phenomena:

1. Size of the sun at dusk
2. Colour of the sun at dawn
3. Moon being visible at dawn
4. Twinkle of stars in the sky
5. Polestar being visible in the sky

Which of the above are optical illusions?

1. 1, 2 and 3
2. 3, 4 and 5
3. 1, 2 and 4
4. 2, 3 and 5

• Polestar we all know is for real and not am optical illusion.
• Eliminate 5
• We also know stars are like sun. As the Sun doesn’t twinkle, stars also should not but they do. That’s optical illusion

11. Rainbow is produced when sunlight falls on drops of rain.

Which of the following physical phenomena are responsible for this?

1. Dispersion
2. Refraction
3. Internal reflection

Select the correct answer using the codes given below.

1. 1 and 2 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

9th std physics

Water droplets act as prisms, refract and disperse the light, light is then reflected internally (total internal reflection) and then refract again while coming out of raindrops.

12. The known forces of nature can be divided into four classes, viz, gravity, electromagnetism, weak nuclear force and strong nuclear force. with reference to them, which one of the following statements is not correct?

1. Gravity is the strongest of the four
2. Electromagnetism act only on particles with an electric charge
3. Weak nuclear force causes radioactivity
4. Strong nuclear force holds protons and nutrons inside the nuclear of an atom.

• Gravitational force is the weakest so 1st is untrue
• Regarding 2nd. Only red flag. Pause and think. Does it act Only on charged particles? I am not sure ?
• Strong nuclear the strongest

13. The efforts to detect the existence of Higgs boson particle have become frequent news in the recent past. What is /are the importance/importance of discovering this particle?

1. It will enable us to understand as to why elementary particles have mass.
2. It will enables us in the near future to develop the technology to transferring matter from one point to another without traversing the physical space between them.
3. It will enable us to create better fuels for nuclear fission.

Select the correct answer using the codes given below:

1. 1 only
2. 2 and 3 only
3. 1 and 3 only
4. 1, 2 and 3

• Was very much in news
• 1st is easily true.
• 3rd is false. How can it create better fuel for fission?