7. (i) An acid is a compound which, when dissolved in water, gives............ (hydronium/hydroxide) ions as the only .............(positive/negative) ions.   8. (ii) Electrolysis is the passage of .................(electricity/electrons) through a liquid or a solution accompanied by a............ (physical/chemical) change.   9. (iii) Allotropy is the property of a (n) ...................(compound/element) which can exist in two more than two forms in the same ................ (chemical/ physical) state.   10. (iv) A (n) .............. (acid/basic) salt is one in which the hydrogen of an acid has been partially replaced by metal (metal/non-metal).   11. (v) The number of atoms present in one .................. (mole/molecule) of an element is called its .................. (acidity/atomicity)