2. The zeros in front do not matter
Answer:

Explanation:
From the question we are told that:
Radius 
Charge Density 
Distance
Generally the equation for electric field is mathematically given by



Answer:
State A = piece of metal; State B = air
Explanation:
For the three main states of matter here's how it breaks down.
Solid - Cannot be compressed and retains its shape
Liquid - Cannot be compressed and does not retain its shape
Gas - Compressible and does not retain its shape.
Knowing this State A has to be solid. Only one of the options has A as a solid, so that's the answer. Worth knowing state B is a gas though, only one compressible, just like solid is the only one that retains its shape.
Im not 100% on these but i can try
1. A compound is made up of elements and their different atoms
2.
A. salt- compound (NaCl) is two elements Na (sodium) and Cl (chloride?)
B. Nitrogen- element its on the periodic table
C. Helium- element its on the periodic table
D. Water- compound (H2O) two elements hydrogen and oxygen
3. element, compound, compound, element
Hope this helps
Momentum
= mass x velocity
= 0.2 x 5
= 1 kg m/s