Answer:
Mass of the object,

Step-by-step explanation:
It is given that,
Charge on an object,

Electric field, E = 620 N/C
We need to find the mass of this object. Let m is the mass of the object. It can be calculated as :

, here a = g (as it is vertically downward)

m = 0.00158 kg

So, the mass of the object is
. Hence, this is the required solution.