Give the ans in english

Here is the answer to question 1:

1. Be's 4th electron will have four quantum numbers

• Step 1: Determine the electronic configuration of Beryllium (Be). Beryllium has an atomic number of 4, meaning it has 4 electrons. The electronic configuration is $1s^2 2s^2$.
• Step 2: Identify the 4th electron. The first two electrons are in the $1s$ orbital. The 3rd and 4th electrons are in the $2s$ orbital. Therefore, the 4th electron is the second electron in the $2s$ orbital.
• Step 3: Determine the quantum numbers for an electron in the $2s$ orbital.
  • The principal quantum number ($n$) for the $2s$ orbital is 2.
  • For an $s$ orbital, the azimuthal quantum number ($l$) is 0.
  • For $l=0$, the magnetic quantum number ($m_l$) can only be 0.
  • Since it is the second electron in the $2s$ orbital, its spin quantum number ($m_s$) will be $-1/2$ (following Pauli's exclusion principle, where the first electron has $+1/2$ and the second has $-1/2$).
• Step 4: The four quantum numbers for Be's 4th electron are $n=2, l=0, m_l=0, s=-1/2$.
• Step 5: Compare these values with the given options.
  • (a) $n=1, l=0, m=0, s=+1/2$
  • (b) $n=1, l=1, m=+1, s=+1/2$
  • (c) $n=2, l=0, m=0, s=-1/2$
  • (d) $n=2, l=1, m=0, s=+1/2$

The correct option is (c).

The final answer is $\boxed{\text{(c)}}$.