Who found an empirical relationship between the half-life of alpha decay and the energy of the emitted alpha particles in 1911?
(A) Fermi and Meitner
(B) Geiger and Nuttall
(C) Chadwick and Lawrence
(D) Soddy and Aston
In 1911, Geiger and Nuttall discovered an empirical relationship between the half-life of alpha decay and the energy of the emitted alpha particles.
Which of the following elements has the largest atomic radii?
(A) Beryllium
(B) Lithium
(C) Nitrogen
(D) Carbon
Francium (Fr) has the highest atomic radius in the periodic table. It belongs to the alkali metals group. Its atomic number is 87. The periodic trend of atomic radius suggests that the atomic radius usually decreases along a period (left to right) and increases down a group (top to bottom).
The coefficient performance of a refrigerator is 5. If the temperature inside the freezer is -20℃, calculate the heat rejected to the surrounding
(A) 110C
(B)
410C
(C)
210C
(D)
310C
A heat pump is a heat engine working in reverse direction. A refrigerator is basically a heat pump, which is used to pump heat (absorbed from materials at lower temperatures inside the refrigerator) to the surroundings at higher temperatures. The coefficient of performance of a refrigerator is defined as the ratio of heat removed
Why
2
Energy from inside the refrigerator per cycle
w
given per cycle for heat removal,
α
,
Why
2
,
w
,
Choose the correct statement
(A) A body can be accelerated by frictional force
(B) There can be zero friction
(C) Kinetic friction is greater than rolling friction
(D) Frictional force and area of contact between the two surfaces are proportional
Find the molecular mass of a gas that takes three times more time to effuse as compared to He with the same volume
(A) 9 u
(B) 64 u
(C) 27 u
(D) 36 u
Its molecular mass will be: 64u.
What are the conditions for gas like Carbon monoxide to obey the ideal gas laws?
(A) Low temperature and low pressure
(B) Low temperature and high pressure
(C) High temperature and low pressure
(D) High temperature and high pressure
A real gas can behave as an ideal gas if volume of molecule is negligible and interaction between molecule is negligible. This will happen if number of molecule per unit volume is very small. This is only possible at high temperature and low pressure.
The observer hears a sound from the source which is moving away from the observer who is stationary. Determine the frequency of the sound
(A) It is halved
(B) It remains the same
(C) It reaches infinity
(D) It gets doubled
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