Answer:
70509.8039216 N/C
Explanation:
k = Coulomb constant = 
q = Charge = 2.00 µC
l = Length of filament = 5.1 m
r = Radius of cylinder = 10 cm

Electric field is given by

The electric field at the surface of the cylinder is 70509.8039216 N/C
It’s definitely the 3rd one
Answer: A characteristic of matter that can be observed without changing the identity of the matter is a physical property.
Explanation:
A property that does not bring any change in chemical composition of a substance are known as physical properties.
For example, shape, size, mass, volume, density, etc of a substance are all physical properties.
Whereas a property that changes chemical composition of a substance is known as chemical property.
For example, precipitation, reactivity, toxicity etc are chemical property.
A chemical change cannot be reverted back.
Therefore, we can conclude that a characteristic of matter that can be observed without changing the identity of the matter is a physical property.