A square Lamina OABC of length 10 cm is pivoted at \( O \). Forces act at Lamina as shown in figure. If Lamina remains stationary, then the magnitude of \( F \) is:
Considering Bohr’s atomic model for hydrogen atom :(A) the energy of H atom in ground state is same as energy of He+ ion in its first excited state. (B) the energy of H atom in ground state is same as that for Li++ ion in its second excited state. (C) the energy of H atom in its ground state is same as that of He+ ion for its ground state. (D) the energy of He+ ion in its first excited state is same as that for Li++ ion in its ground state.