Which value is indicated by the period number in the modern periodic table?

1. Atomic number

2. Atomic mass

3. Principal quantum number

4. Azimuthal quantum number.

Which of the following sets of quantum numbers is possible :
1. n = 0, l = 0, m_l = 0, m_s = + ½
2. n = 1, l = 0, m_l = 0, m_s = – ½
3. n = 1, l = 1, m_l = 0, m_s = + ½
4. n = 3, l = 3, m_l = –3, m_s = + ½

The total number of electrons in an atom with the following quantum numbers would be
(a) n = 4, m_s = – ½ 
(b) n = 3, l = 0
1. 16,  2
2. 11, 8
3. 16, 8
4. 12, 7