The Richter Scale<span> is not commonly </span>used<span> anymore, except for small </span>earthquakes<span>recorded locally, for which ML and Mblg are the only </span>magnitudes<span> that can be measured. For all other </span>earthquakes<span>, the </span>moment magnitude scale<span> is a more accurate measure of the </span>earthquake<span> size.</span>
We know, Volume = Mass / Density
Here, mass = 4 Kg = 4000 g
d = 1,897 g/ml
Substitute their values,
v = 4000 / 1897
v = 2.108 ml
In short, Your Answer would be 2.108 mL
Hope this helps!
Answer: Total work done on the block is 3670.5 Joules.
Step by step:
Work done:

With F the force, d the displacement, and theta the angle of action (which is 0 since the block is pushed along the direction of displacement, and cos 0 = 1)

Given:
F = 75 N
m = 31.8 kg
Final velocity 
In order to calculate the Work we need to determine the displacement, or distance the block travels. We can use the information about F and m to first figure out the acceleration:

Now we can determine the displacement from the following formula:

Here, the initial displacement is 0 and initial velocity is also 0 (at rest):

Now we still have "t" as unknown. But we are given one more bit of information from which this can be determined:

(using vf as final velocity, and tf as final time)
So it takes about 6.44 seconds for the block to move. This allows us to finally calculate the displacement:

and the corresponding work:
