Physics Questions

Q:

What is the minimum distance (in metres) required to hear an echo?

A) 10 B) 13
C) 17 D) 21
 
Answer & Explanation Answer: C) 17

Explanation:
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Q:

For a certain reaction,DGq = -45 kJ/mol and DHq= -90 kJ/mol at 0°C. What is the minimum temperature at which the reaction will become spontaneous, ifDHq and DSq are independent of temperature?

A) 273 K B) 298 K
C) 546 K D) 596 K
 
Answer & Explanation Answer: C) 546 K

Explanation:

T = 273 °K

Using the formula,

DGq = DHq –TDS

-45 = -90 –273 DS

DS = 0.164

Now since DHq and DSq are independent,T2= DH/DS = 45/0.164 = 273°K

Required Temp = 273 + 273 = 546°K

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Q:

The fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by

A) Galileo B) Martin Luther
C) Johannes Kepler D) Copernicus
 
Answer & Explanation Answer: C) Johannes Kepler

Explanation:

Kepler’s  laws  of  planetary  motion state  that  (a)  All  planets  move  in elliptical orbits with the Sun at one of  the  focal  points  (b)  The  radius vector  drawn  from  the  sun  to  a planet  sweeps  out  equal  areas  in equal  time  intervals.  This  follows from  the  fact  that  the  force  of gravitation on the planet is central and  hence  angular  momentum  is conserved.  (c)  The  square  of  the orbital   period   of   a   planet   is proportional  to  the  cube  of  the semi  major  axis  of  the  elliptical orbit of the plane.

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Q:

An electric iron of 750 W is used for S hours per day. Then the energy consumed in one day by the iron is:

A) 6 units B) 600 units
C) 0.6 units D) 60 units
 
Answer & Explanation Answer: A) 6 units

Explanation:
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Q:

We are able to walk on earth without slipping because of

A) Gravitational force B) Frictional force
C) Viscous force D) Centrifugal force
 
Answer & Explanation Answer: B) Frictional force

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Q:

Which of the following performs modulation and demodulation?

A) coaxial cable B) modem
C) fiber optic D) satellite
 
Answer & Explanation Answer: B) modem

Explanation:

A modem is a hardware device which performs both modulation and demodulation. MODEM means (Modulator-Demodulator).

 modem_1593758111.png image

 

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Q:

Temperature of distant luminous bodies can be determined by

A) Mercury thermometers B) Gas thermometers
C) Pyrometers D) Colour thermometers
 
Answer & Explanation Answer: C) Pyrometers

Explanation:
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Q:

_______ optical data storage is a technology where data is stored in multiple layers in the optical disc.

A) 3D B) 30D
C) 300D D) 3000D
 
Answer & Explanation Answer: A) 3D

Explanation:
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