How many moleules of SiO2 would be needed to have a mass of 12.40 grams

Is this a single replacement reaction or there is no

Which of the following statements about acidic water is true? a. acid has no effect on the h,o molecules. b. the solution contains a larger number of oh ions than h,o ions. c. the solution contains a larger number of h,o ions than qh ions. d. the solution contains an equal number of h,o ions and oh ions. none of the above e.

How do you identify the anode on a power source such as a battery? how do you identify the cathode? how are terms anion and cation?