A person presents with following parameters PCO2 – 30 mm of Hg, PO2 – 105 mm of Hg, pH – 7.45 is having partially compensated -
Metabolic acidosis
Metabolic alkalosis
Respiratory acidosis
Respiratory alkalosis
Increase in pH suggests alkalosis

PCO2 is decreased, this suggests respiratory alkalosis.
The metabolic component cannot be evaluated as data is not provided. So the diagnosis seems to be respiratory alkalosis.