Answer:
A. Materials with a low index of refraction cause light to refract very little.
Answer:
Mass of the box is 25kg
Explanation:
From Newton's second law of motion
Force= mass. acceleration
With the symbol
F=m.a
m=F/a m=(50N)/(2m/s²)
m=25kg
Answer:

Explanation:
The water droplet is initially neutral, it will obtain a 40 nC of charge when a charge of -40 nC is removed from the water droplet.
The charge on one electron, 
Let the N number of electrons have charge -40 nC, such that,
Now, mass of one electron = 
Therefore, mass of N electrons = 
It is the mass of the of the water droplet that must be removed in order to obtain a charge of 40 nC.
Let it is m times the total mass of the droplet which is 
Then,

It is the required fraction of mass of the droplet.
An object with volume greater than it mass. to account less density and thus it will float