66. (i) Acids dissolve in water to produce positively charged ions. Draw the structure of these positive ions.   67. (ii) Explain why Carbon tetrachloride does not dissolve in water.   68. (iii) Elements Q and S react together to form an ionic compound. Under normal conditions, which physical state will the compound QS exist in?   69. (iv) Can Q and S, both be metals? Justify your answer.