in equation Zn+HCl - ZnCl2 +H2. HOW THIS EQUATION MY BE FORMED , HOW ZnCl2 FORMED.
This is a displacement reaction. Zinc is more reactive than hydrogen, so it will displace hydrogen from HCl forming zinc chloride and H2 gas.The balanced equation is:
Zn + 2HCl → ZnCl2 +H2