Question

at constant temperature 200cm3 of n2 at 720mm and 400cm3 of o2 at 750mm pressure are put together in a one litre flask.the final temperature of mixture is

Answer 1

i think your question is wrong you mentioned that pressure is constant then that mean you want to know about final pressure of mixture that may be due to mistyping so,

According to the question 
Volume of N2 = 200cm^3 =200ml =0.2L
Pressure of N2=720mm
volume of 02 =400cm^3 =400ml = 0.4 L
pressure of oxygen =750 mm
 Total pressure= pressure of nitrogen+pressure of oxygen 
                      =720+750 =1470 mm
 as we know volume of falsk is 1 liter and pressure is unknown
using the equation
P1 * V1 = P2 *V2
1470*0.6= P2 *1
P2= 882 mm of hg will be the finall pressure

Answer 2

Answer:

Explanation:

Use formula

PV=P1V1+P2V2