Answer:
B) Yes, but only those electrons with energy greater than the potential difference established between the grid and the collector will reach the collector.
Explanation:
In the case when the collector would held at a negative voltage i.e. small with regard to grid So yes the accelerated electrons would be reach to the collecting plate as the kinetic energy would be more than the potential energy that because of negative potential
so according to the given situation, the option b is correct
And, the rest of the options are wrong
Answer:
The magnitude of electron acceleration is

Explanation:
Given:
Distance from the wire to the field point
m
Speed of electron 
Current
A
For finding the acceleration,
First find the magnetic field due to wire,

Where 

T
The magnetic force exerted on the electron passing through straight wire,

N
From the newton's second law

Where
mass of electron
kg
So acceleration is given by,



Therefore, the magnitude of electron acceleration is

The density of ice is less than the density of water. C
Answer:
308,000 or 30.8×10^3
Explanation:
v=f×lamda
v is ?, f is 875Hz, lamda is 352m
v=875×352
v=308,000
v=30.8×10^3 m/s