The phrase "a question on which" is correct and usable in written English.
It can be used when referring to a specific question that serves as a basis for further discussion or inquiry.
Example: "There is a question on which we need to reach a consensus before moving forward with the project."
Alternatives: "a question regarding" or "a question about".
It is not clear whether the conference will address whether condoms are appropriate for married couples in which only one partner is infected with HIV, a question on which the church has made no definitive pronouncement.
This case is one of first impression for us, and decides a question on which the state and lower federal courts have been divided.
How essential vitamin supplementation is in the adult dog is a question on which veterinary opinion differs.
Governor Romney, I wanted to start by asking you a question on which every American has formed an opinion.
Whether he crossed the line wilfully, or was pushed, is a question on which it is necessary to return an open verdict.
The law's impact on jobs depends, in part, on whether it will slow the growth of health costs, a question on which expert opinion is divided.
Russert then threw out a question on Russia, which he later said on MSNBC was a "jump ball," which even the wingnuts knew was a gotcha.
A concurring opinion by Justice Stephen G. Breyer, joined by Justice Ruth Bader Ginsburg, suggested that the court should give the political branches considerable leeway in sorting out a difficult question on which "a legislature has significantly greater institutional expertise" than a court.
One of the most striking omissions from this year's census is a question on religion, which was excluded after a heated debate.
To focus their efforts, each organisation was asked to come up with a question on gender, which they would investigate over the six months and then develop a concreten action plan.
"But by including a question on citizenship, which is not required by the Constitution, the Trump Administration is exploiting the fear of immigrant communities who are already reticent to divulge personal information to the federal government".
