Question

cas + hcl → acl₂ + h₂s

Explanation:

Step1: Balance calcium (Ca)

On the left - hand side, there is 1 Ca in CaS. On the right - hand side, in CaCl₂, there is 1 Ca. So the coefficient of CaCl₂ is 1 as given, and Ca is already balanced.

Step2: Balance sulfur (S)

There is 1 S in CaS on the left - hand side and 1 S in H₂S on the right - hand side. So the coefficient of H₂S is 1.

Step3: Balance hydrogen (H) and chlorine (Cl)

On the left - hand side, we have 2 H and 2 Cl in 2HCl. On the right - hand side, in CaCl₂ there are 2 Cl and in H₂S there are 2 H. So the equation is balanced.

Answer:

1