Except 'Volume' all other words have two vowels. Volume has three vowels.

'Orange' is the only citrus fruit.

'Mercury' is liquid at room temperature.

Expect 'Driving', all activities are related to water but driving is related road.

Only 'Gallon' is different because this is use for liquid measurement.

'Dam' is different among the given alternatives as dam is used to stop the water from flowing while in spring, stream and river, water flows.

'Stag' is made while mare, lioness and bitch are female. Thus, stage is different.

The colors Green, Indigo and Violet are constituents of the pattern 'VIBGYOR' . Whereas pink is not a part of VIBGYOR.

In this question, the word Debit, Deduction and Withdrawal are very much similar in the meaning , whereas Deposit is antonym of these words.

Each of jupiter, Uranus and Earth has satellite while Mercury dosen't have its satellite. Thus, Mercury is different.