As temperature and number of moles of gas remained unchanged, use the formula #P_1*V_1 = P_2*V_2#, where #P_1# and #P_2# are the old and new pressures and #V_1# and #V_2# are the old and new volumes respectively, to calculate the volume of gas.

You must convert the pressures into a single unit. The best option is to convert the new pressure, given in mmHg, into atm. As we know, #1 atm = 760 mmHg#

Therefore, #738mmHg = 738/760 atm#. For the sake of accuracy, we are going to used this fraction rather than the irrational decimal value.

#P_1*V_1 = P_2*V_2#

#P_1 = 1 atm#

#V_1 = 652mL#

#P_2 = 738/760 atm#

#V_2 = ?#

Putting in all the known values, we have:

#1atm*652mL = 738/760 atm * V_2mL#

#V_2 = (1atm*652mL)/(738/760atm)#

#V_2 = 671.436mL#