Reagent is:
Na
HCl and H2O
KOH in C2 H5 OH
Zn
(c) R−CH2−CCl2−RKOH + C2H5OH−−−−−−−−−−−→R−C≡C−R
This reaction is an example of dehydrohalogenation.
Hence, alcoholic KOH is used as a reagent.