If a microphone has an output voltage of 2.5mV @ 1Pa, what would its output voltage be when 98dB SPL is applied to the diaphragm?
The reference pressure for dbSPL is 20 micro Pascal so 1 Pascal is roughly 94 dB SPL.  98 dB SPL is about 1.59 Pa and the output voltage of your microphone would be around 3.7 mV.