Place the chicken broth in large saucepan and bring to a boil. If there is not 5 cups of broth, add enough reserved mushroom liquid to make 5 cups. Cover and simmer for 5 minutes. Add mushrooms to broth and simmer until heated through. Add soy sauce and noodles. Stir well and simmer for 3 minutes more. Divide sliced chicken equally into 4 bowls. Pour soup on top, Garnish with a lemon slice. Serves 4.