Which is a true statement?

A. The nucleus is found in the center of atoms and contain protons and electrons
B. The nucleus is found in the center of atoms and contains protons and neutrons
C. Electrons have a neutral charge
D. Neutrons have a negative charge

PLEASE HELP D:

The magnitude of the magnetic field at a certain distance from a long, straight conductor is represented by b. what is the magnitude of the magnetic field at twice the distance from the conductor? a. at twice the distance, the magnitude of the field is 4b.b. at twice the distance, the magnitude of the field is 2b.c. at twice the distance, the magnitude of the field is b/2.d. at twice the distance, the magnitude of the field is b/4.e. at twice the distance, the magnitude of the field remains equal to b.