Answer:
r = 5.08 m
Explanation:
The electric force of attraction or repulsion is given by :

We need to find how far above the electron would the proton have to be if you wanted to hold up an electron against the force of gravity by the attraction of a fixed proton some distance above it.
So, the force from the proton is balanced by the mass of the electron.

r is distance

So, proton have to be at a distance of 5.08 meters above the electron.
I think it could be D please tell me if I’m wrong I hope you have a wonderful day ❤️
Answer:

Explanation:
Generally the workdone in moving the proton is mathematically represented as

Where 
So

Here
is the velocity at A with value 50 m/s
So


Also

Here
is the velocity at A with value 
=> 
=>
So


Now this workdone is also mathematically represented as

So

Here 
So


Generally proton movement is in the direction of the electric field it means that 
So

Answer:
(a) decrease
Explanation:
Viscosity is the resistance which occur to flow of the fluid.
More the inter molecular forces between particles of the liquid, more the viscosity of liquid.
<u>Effect of temperature on viscosity:-</u>
Viscosity decreases with the increase in the temperature as forces among the particles decrease on increasing temperature. The kinetic energy of the particles of the liquid increases causing to move in more random motions and thus weaker inter molecular forces and this offer less resistance to the flow.
<u>Hence, viscosity of the liquids decrease with the increasing temperature.</u>