Answer:
a) 
b) 
Explanation:
Given:
height of water in one arm of the u-tube, 
a)
Gauge pressure at the water-mercury interface,:

we've the density of the water 


b)
Now the same pressure is balanced by the mercury column in the other arm of the tube:



<u>Now the difference in the column is :</u>



A material that has high resistance to the flow of electric current is called an electric resistor
Nice paddling. Thanks for sharing.
Do you have some question to ask ?
A fire because you feed it wood, it lives longer but if you give it a drink, water, then it dies.