The 3 in 4p3 represents:
a. third energy level
b. the number of electrons
c. period 3
d. the third sub level e. li

b. the number of electrons

Explanation:

1. 4 is the principal quantum number which describes the size of the orbital. It is represented by n.

2. The electrons are present in p sub shell also called as azimuthal quantum Number: This quantum number describes the shape of the orbital. It is represented as 'l'. The value of l ranges from 0 to (n-1). For p orbital, l=1.

3. The p subshell contains 3 electrons.