You have 357 ml of chlorine trifluoride gas at 699 mmhg and 45 celsius what is the mass of the sample

To find the weight of the gas you need to find the number of moles of using ideal gas formula. Remember to change the temperature unit to Kelvin and the pressure to kpa or atm

PV=nRT
n= PV/RT
n= 699 mmHg* 0.1333kpa * 0.357 L/   8.314 kpa*L  / mol*K  * (45 +273.15)K
n=0.012 moles

weight= n * molecular weight
weght= 0.012 *92.448 g/mol= 1.109 grams

☆ionisation energy increases across a period from na -> ar☆ionisation energy decreases down a group from li -> fr☆ionic radius decreases across a period from na -> cl☆ionic radius increases down a groupfrom f -> ii hope it clarifies your doubts