__BaF2+__Na2S-->__BaS2+__NaF

The reaction can't be balanced

Explanation:

To solve the chemical reaction:

_BaF₂ + _Na₂S → _BaS₂ + _NaF

We will use the algebraic method:

XBaF₂ + YNa₂S → ZBaS₂ + WNaF

Ba = X = Z

F = X/2 = W

Na = Y/2 = W

S = Y = Z/2

From the equations of F and Na:

X= Y

But from Ba and S equations:

X = 2Y

As both equations are inconsistent:

chemical digestion occurs in the stomach were hcl and pepsin forms chyme, the mouth in which salivary amylase breaks down starch to form bolus, and the small intestine specifically the duodenum.