Question

The electric field that is 0.25m from a small sphere is 450n/c toward the sphere.

Answer 1

Its b bc its the volume of the sphere 

Answer 2

PART 1)

A small sphere is considered to be a point charge

So here if electric field is indicating the position of charge itself or it is towards the charge then it must be a negative charge on the sphere

PART 2)

Electric field due to a point charge is given by

$E = \frac{KQ}{r^2}$

here

$k = 9 * 10^9$

$Q = charge$

$r$ = distance of charge from the point where field strength is required

= 0.25 m

$E = 450 N/c$

now from the above equation we can say

$450 = \frac{9*10^9 * Q}{0.25^2}$

$Q = 3.125 * 10^{-9} C$

So magnitude of charge is 3.125 nC on the small sphere