The following procedure was carried out to determine thevolume
of a flask. the flask was weighed dry and then filled withwater. if
the masses of the empty flask and filled flask were 56.12g and
87.39 g, respectively, and the density of water is 0.9976g/ml,
calculate the volume of the flask in ml.

Volume of the flask is 31.34 mL.

Explanation:

Weight of empty flask  = 56.12 grams

Weight of flask with water   = 87.39 grams

Weight of water =  = (87.39 - 56.12) grams= 31.27 grams  

Density of water =  0.9976 g/mL

0.9976 grams are contained in = 1 ml of water

Thus 31.27 grams  are contained in = ml of water.

Thus the volume of the flask is 31.34 mL.