Answer : The correct option is, (C) 32.0 mL
Explanation :
Formula used :
[tex]M_1V_1=M_2V_2[/tex]
where,
[tex]M_1\text{ and }V_1[/tex] are the initial molarity and volume of NH₃.
[tex]M_2\text{ and }V_2[/tex] are the final molarity and volume of HCl.
We are given:
[tex]M_1=0.32M\\V_1=50mL\\M_2=0.5M\\V_2=?[/tex]
Now put all the given values in above equation, we get:
[tex]0.32M\times 50mL=0.5M\times V_2\\\\V_2=32.0mL[/tex]
Hence, the volume of hydrochloric acid added to react completely with the ammonia must be, 32.0 mL