What is the atomic number of gold?

When the potential of the second excited state of an atom is $108.8 \ V$,the recoil energy of the atom is ...... Joules.

Which of the following atoms has the lowest ionization potential?

An electron collides with an atom in its ground state. The atom then emits a photon of energy $E_{photon}$. In this process,the change $\Delta E_{elec}$ in the electron's energy is

Given below are two statements:
Statement $I$: Atoms are electrically neutral as they contain equal number of positive and negative charges.
Statement $II$: Atoms of each element are stable and emit their characteristic spectrum.
In the light of the above statements,choose the most appropriate answer from the options given below.

The graph between the square root of the frequency of a specific line of characteristic spectrum of $X$-rays and the atomic number of the target will be