a harp :)
The quietest instrument in an orchestra is the triangle.
The tuba is the biggest brass instrument used in a symphony orchestra. (There are some very rare special pieces of music where a composer might call for an instrument that is not normally in an orchestra. For example, there is a family of brass instruments called ophicleides that were used in the 1800's, and those came in many sizes, including ones as big as the tuba.)
The violin is the smallest stringed instrument in an orchestra.
The instrument in an orchestra that has the highest pitch is the violin.
Usually the bass, unless they're playing Saint-Saens 3. Then it's the pipe organ.
The largest orchestra? Actually, the size of any orchestra is determined by the composer who will specifically call out which and how many of each instrument is to be used when playing his/her work. Orchestra sizes range from about 40 to 110 members in all. Not all are used for every work.
The clarinet.
A Standard orchestra but with only one instrument of each instrument
Contrabassoon
That depends entirely on which orchestra is in question.
which instrument has a bell?
Keyboard and harpsota can