The relative humidity of air is 80% at 27 o C . .If the aqueous tension at the same temperature is 27 mm of Hg . The partial pressure of water vapour in the air will be (in mm of Hg ).

Step-by-step solution

Relative humidity = P a r t i a l p r e s s u r e V a p o u r p r e s s u r e × 100 ⇒ P a r t i a l p r e s s u r e 27 × 100 = 80 ⇒ P a r t i a l p r e s s u r e = 80 × 27 100 ∴ P a r t i a l p r e s s u r e = 21.6 m m of Hg