7. a bálloon containing 1 mole air at 1 atm initially is filled further with air till pressure increases to 4 atm. the initial diameter of the balloon is 1 m an

7. A bálloon containing 1 mole air at 1 atm initially is filled further with air till pressure increases to 4 atm. The initial diameter of the balloon is 1 m and the pressure at cach stage is proportion to diameter of the balloon. How many no. of moles of air added to change the pressure from 1 atm to 4 atm. (a) 80 (b) 257 () 255 (d) 256 8. IfPd ws P(where P denotes pressure in atm and d denotes density in gm/L) is plotted for He gas (assume ideal) at a particular temperature. If -5, then the temperature Jp-s21 will e (a) 160 K b) 320 K (c)80 K (d) none of these ( solution of these 2 questions )