When energy is transformed, the amount of usable energy?

Consider a hydrogen atom in the ground state. what is the energy of its electron? =e= jj now consider an excited‑state hydrogen atom. what is the energy of the electron in the =5n=5 level? =e5= j

Ascientist wants to test ways to reduce pollution in lake . what is the bestway of doing this

The statue of liberty is 305.5 feet high. when the angle of elevation of the sun is 50 , what is the distance to the tip of the shadow from a point at water level and directly below the highest point of the statue?