Read the passage and answer the questions below.

5 ml of content from bottle A is mixed with 5 ml of content from bottle B . The resultant mixture, when tested, detects the presence of $I$. If it is known that bottle $A$ contains only $P$, what BEST can be concluded about the volume of I in bottle B?

There are four bottles. Each bottle is known to contain only $P$ or only I. They will be considered to be "collectively ready for dIspatch" if all of them contain only P . In minimum how many tests, is it possible to ascertain whether these four bottles are "collectively ready for dIspatch"?

There are four bottles. It is known that three of these bottles contain only $P$, while the remaining one contains $80 \% \mathrm{P}$ and $20 \% \mathrm{I}$. What is the minimum number of tests required to definitely identify the bottle containing some amount of $I$ ?

There are four bottles. It is known that either one or two of these bottles contain(s) only $P$, while the remaining ones contain $85 \% \mathrm{P}$ and $15 \% \mathrm{I}$. What is the minimum number of tests required to ascertain the exact number of bottles containing only $P$ ?