Answer: Option (B) is the correct answer.
Explanation:
Convection is defined as a process in which a fluid (liquid or gas) is heated and the cooler liquid (more dense) settles or sinks at the bottom whereas a hotter material (less dense) will rises to the top.
For example, ice being less dense (cooler material) will float in a lake whereas liquid water being more dense will sink at the bottom.
Thus, we can conclude that situation in which convection currents most likely occur is within the water in a lake as ice forms on the top.
Answer:
a)
m/s
b)
Angular frequency = 
Explanation:
As we know

q is the charge on the electron =
C
B is the magnetic field in Tesla =
T
r is the radius of the circle =
m
mass of the electrons =
Kg
a)
Substituting the given values in above equation, we get -
m/s
b)
Angular frequency =

I’m pretty sure it’s circuit three.
To answer this question is necessary to apply the concepts related to Bernoulli's equation. The Bernoulli-related concept describes the behavior of a liquid moving along a streamline. Pressure can be defined as the proportional ratio between height, density and gravity:

Where,
h = Height
= Density
g = Gravity
Our values are
density of water at normal conditions
h = 7.3m

PART A) Replacing these values to find the total pressure difference we have to



In this way the pressure change would be subject to




PART B) Considering the pressure gauge of the group as the ideal so that at a height H the water cannot flow even if it is open we have to,



Therefore the high which could a faucet be before no water would flow from it is 21.42m