Answer:
perihelion
Explanation:
The point at which a planet is closest to the sun is called perihelion. The farthest point is called aphelion
Answer: When 
Explanation:
According to first law of thermodynamics, energy can neither be created nor be destroyed. It can only be transformed from one form to another.


= change in enthalpy
P = pressure
= change in volume
=Change in internal energy
q = heat absorbed or released
w = work done on or by the system

Thus for
, 
The heat evolved or absorbed by the system in a physical or chemical process, equal the change in enthalpy of the system when 
Answer:

Explanation:
From the question we are told that
Nucleus diameter 
a 12C nucleus
Required kinetic energy 
Generally initial speed of proton must be determined,applying the law of conservation of energy we have

where
=initial kinetic energy
=final kinetic energy
=initial electric potential
=final electric potential
mathematically

where
=distance b/w charges
=nucleus charge 
=constant
=proton charge
Generally kinetic energy is know as

Therefore
Generally equation for radius is 
Mathematically solving for radius of nucleus


Generally we can easily solving mathematically substitute into v_1









Therefore the proton must be fired out with a speed of 
Answer:
a
Explanation:
The most reasonable conclusion of the above phenomenon is that water is a poor conductor of heat. Basically water is an insulator. The heat from surface to the bottom of the beaker will take a lot of time. Moreover, no convection current is formed so, heat might not even reach the bottom surface. Hydrogen bonding also play a vital role in determining the thermal properties of water.
hence option A is correct