The answer is mass. I have to comment more than 20 characters.
Answer:
(a) 0.345 T
(b) 0.389 T
Solution:
As per the question:
Hall emf, 
Magnetic Field, B = 0.10 T
Hall emf, 
Now,
Drift velocity, 

Now, the expression for the electric field is given by:
(1)
And

Thus eqn (1) becomes
where
d = distance
(2)
(a) When 

(b) When 

Construction, like building a home/building, digging, like in a mine, and opening a soda can, where the part to open is a lever.
Answer: C
Explanation: Side post terminals need to be removed to inspect them for corrosion.
Over tightening the terminal bolt can damage side post terminals.
The battery terminals and cable ends can corrode especially when the battery or car is not used for a long period of time. Corrosion limits a battery's lifespan and so should be prevented. To inspect the areas where corrosion occur on a side-post battery, you need to remove the terminals.
Also, it is true that over tightening the terminal bolt can damage the side post terminals. The covering on the battery can become twisted, and make the seals on the terminals leak.