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Q:

The process that takes place in the atom bomb is

A) nuclear fusion B) nuclear fission
C) radioactive disintegration D) chemical decomposition
 
Answer & Explanation Answer: B) nuclear fission

Explanation:

In the atom bomb, isotopes of uranium are  disintegrated with the release of a large amount of energy. Hence, the process is nuclear fission.

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Filed Under: Chemistry

Q:

Which of the following is called 'the King of Chemicals' ?

A) Nitric acid B) Hydrochloric acid
C) Silver nitrate D) Sulphuric acid
 
Answer & Explanation Answer: D) Sulphuric acid

Explanation:

Sulphuric acid is called the King of Chemicals because it is used in the preparation of a very large number of other useful chemicals such as hydrochloric acid, nitric acid, dyes, drugs etc. In fact the annual production of shulpuric acid in a country is a measure of the economy of the country.

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Filed Under: Chemistry

Q:

According to the modern Periodic Law, the properties of elements are periodic functions of their

A) volency B) atomic mass
C) number of neutrons D) atomic number
 
Answer & Explanation Answer: D) atomic number

Explanation:

Atomic number is the serial number of an element in the periodic classification of elements. It gives the number of protons and also the number of electrons in an atom.

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Filed Under: Chemistry

Q:

A nuclear reactor is said to have become 'critical' when 

A) it stops due to malfunctioning B) it starts emitting dangerous radioactive radiations
C) it is shut down to avoid explosion D) it is ready to produce controlled energy
 
Answer & Explanation Answer: D) it is ready to produce controlled energy

Explanation:

To produce controlled energy i.e energy at a controlled or steady rate, the number of fissions per second must be controlled and maintained at that rate. Excess neutrons should be absorbed by control roads like cadmium.

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Filed Under: Physics

Q:

The electrical domestic tube light gives white fluorescent light because of

A) colision between molecules of filled gas under electric current B) heavy current
C) vacuum inside the tube D) falling of ultra violet rays on the white inner coating of the tube
 
Answer & Explanation Answer: D) falling of ultra violet rays on the white inner coating of the tube

Explanation:

The ultraviolet rays have high frequency and shorter wavelength are converted to visible white light with lower frequency and greater wave length

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Filed Under: Physics

Q:

Lightning is produced when 

A) Similar charges of electricity rush towards each other and then get repelled B) clouds strike against impurities in air and the friction burns up these impurities
C) strong opposite charges in different clouds break down the resistance offered by the intervening air D) water vapour produces electricity in the clouds
 
Answer & Explanation Answer: C) strong opposite charges in different clouds break down the resistance offered by the intervening air

Explanation:

When the resistance of the air between breaks down the current flows from the positive cloud to the negative cloud in a flash which we call lightning . The difference of potential involves is very high.

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Filed Under: Physics

Q:

The velocity required to place a vehicle in orbit round the moon is _______ that required to place it in orbit round the earth 

A) less than B) Greater than
C) equal to D) greater than or equal to
 
Answer & Explanation Answer: A) less than

Explanation:

This orbital velocity at the moon is less because orbital velocity = rg

 

where 'r ' is the orbital radius. i.e the distance of the body from the center of the earth and 'g' is the acceleration due to gravity on the body in question. In the case of the moon, both r and g are less than in the case of the earth.

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Filed Under: Physics
Exam Prep: AIEEE , GATE

Q:

Rain drops acquire spherical shape due to 

A) viscosity B) surface tension
C) friction D) elasticity
 
Answer & Explanation Answer: B) surface tension

Explanation:

The Surface tension pulls the surface of the drop equally at all points thus produces the spherical shape having the minimum surface area. This surface tension is the "skin" of a body of water that makes the molecules stick together.

                                 Rain_drops_acquire_spherical_shape_due_to1558074071.png image 

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Filed Under: Physics
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