Why is the second resonance found feebler than the first ?

Why the second lonization energy is more than the first ionization energy for any element ?

Why the second ionization enthalpy is greater than the first ionization enthalpy?

A student performed the experiment to measure the speed of sound in air using resonance air-column method. Two resonances in the air-column were obtained by lowering the water level. The resonance with the shorter air-column is the first resonance and that with the longer air-column is the second resonance. Then, A. the intensity of the sound heard at the first resonance was more than at the second resonance B. the prongs of the tuning fork were kept in a horizontal plane above the resonance tube C. the ampitude of vibration of the end of the prongs is typically around 1 cm D. the length of the air-column at the first resonance was somewhat than 1//4 th of the wavelength of the sound in air.

The the resonance tube experiment first resonant length is l_(1) and the second resonant length is l_(2) , then the third resonant length will be ?

The the resonance tube experiment first resonant length is l_(1) and the second resonant length is l_(2) , then the third resonant length will be ?

Why is the second ionisation energy of an element much greater than its first ionisation energy ?