Mass.
Because mass doesn't depend on weight but weight depends on mass.
<h2>
Answer:50
</h2>
Explanation:
Let
be the airspeed.
Let
be the cross wind speed.
We know that,ground speed is the vector sum of airspeed and cross wind speed and airspeed is perpendicular to cross wind speed.
If
and
are two perpendicular vectors,the resultant vector has the magnitude 
Given,

So,the ground speed is 
It's mostly used in CHEMICAL PROCESSES.
Answer:
C. rollback
Explanation:
The retina of the eye is located inside the eye making it impossible for the retina to roll back. Only the eye itself can rollback.
Their atomic number?? (easy guess)