Answer: No one. All these molecules are nonpolar.
Explanation: Dipole-dipole attractions occur only between polar molecules. To know if a molecule is polar, you have to observe if their dipole moment (μ) is different from 0. You can do this by observing the vectors of charge in each molecule.
In all the molecules of the alternatives, the overall molecule is nonpolar (the sum of the vectors is equal to 0). So, these molecules are attracted only by induced dipole forces (weak forces that exist between nonpolar molecules).
For F2, this molecule is nonpolar because is composed of equal atoms. So, there isn't an atom which pulls the charge for itself.
Answer:
<h3>Therefore, after long period of time 80kg of salt will remain in tank</h3>
Explanation:
given amount of salt at time t is A(t)
initial amount of salt =300 gm =0.3kg
=>A(0)=0.3
rate of salt inflow =5*0.4= 2 kg/min
rate of salt out flow =5*A/(200)=A/40
rate of change of salt at time t , dA/dt= rate of salt inflow- ratew of salt outflow

integrating factor

integrating factor 
multiply on both sides by 

integrate on both sides
b)
after long period of time means t - > ∞

<h3>Therefore, after long period of time 80kg of salt will remain in tank</h3>
Hey there!
I can't be sure my answers are the exact words, but it should be something along the lines of...
The amount of water on Earth is constant, but the form and location of the water changes as it moves through the water cycle.
This means that Earth has always had the same amount of water within in, along with it being the same water the whole time. No new water was introduced to our planet. Some of our water is liquid, some is solid, and some is gas. Some is deep in the soil and some is high up in the atmosphere. Some is in rain and some is in snow.
I hope this helps!