Answer:
620.71 L the final volume of the balloon.
Explanation:
Initial volume of the gas in the balloon= 
Initial pressure of the gas in the balloon= 
Initial temperature of the gas in the balloon= 
Moles of gases = n
...[1]
Final volume of the gas in the balloon = 
Final pressure of the gas in the balloon = 
Final temperature of the gas in the balloon = 
Moles of gases = n
...[2]
[1] = [2]



620.71 L the final volume of the balloon.
Answer:
C) 0.121 M
Explanation:
HCl + H₂O = H₃O⁺ + OH⁻
.121M .121M
HCl is a strong acid . It will dissociate almost 100 % so the concentration of acid and hydronium ion formed will be equal . It is to be noted that hydronium ion is formed due to association of H⁺ and H₂O . H⁺ is formed due to ionisation of HCl .
So concentrtion of hydronium ion ( H₃O⁺ ) will be .121 M.