Processes and apparatuses are provided for contactless measuring or monitoring in-situ and in real time composition or other electromagnetic impedance correlated properties of liquid or gaseous substances or bulk materials. One or more apparatus may include a resonance type impedance sensor having at least two coils, at least one coil of the at least two coils being at least one excitation coil connectable to at least one alternating current source with frequency sweep, at least one other coil of the at least two coils being at least one sensing coil connectable to at least one data processing system. The one or more methods may include calculating changes in amplitude and resonant frequency induced by electromagnetic interaction between said sensor and object to determine impedance of said object under test; and matching said impedance with predetermined calibration data to determine said chemical or physical properties of said object under test.