Scholarship students sitting their chemistry exam at the end of last year were asked to explain the reaction process that takes place in a date-rape drug.

In the NCEA exam administered by the New Zealand Qualifications Authority (NZQA) students were told rohypnol, commonly known as roofies, was a "controversial sedative which has sometimes been used to spike people's drinks".

An NZQA spokeswoman said the exam papers were written by a team including experienced teachers who were currently teaching at scholarship level.

"All examination papers undergo a sensitivity check and this examination did go through that process."

While the question referring to the date-rape drug raised some concern during the screening process, it was deemed appropriate and published because most of the students sitting the exam would be 18.

"The candidates sitting the examination are considered the brightest senior secondary school chemistry students. The question and answer did not involve or require any value judgment being made, and no information about the making of the drug was provided," an NZQA spokeswoman said.

While no complaints had been received about the chemistry question it was "noted" by one other person on the day of the exam.

Secondary Schools Principals' Association president Tom Parsons said the issue of date-rape drugs was topical and raising it in an exam environment would engage kids.

"It's important to pick topics that engage kids and that they have intellectual curiosity about . . . providing it wasn't glamourising the issue, it's a legitimate examination question."

Given there were no complaints, and the question was "flagged and screened, then it appears NZQA have made the appropriate call", Post Primary Teachers Association president Angela Roberts said.

Family First national director Bob McCoskrie said teenagers needed to be aware of the effects drugs such as rohypnol, marijuana, methamphetamine and party pills had. Knowing the chemical process and reaction involved was a good thing and, while he understood some people might think it gave teenagers the wrong idea, most of them knew about those drugs already.

"There would be a red flag if it was glamourising or condoning it, but given it's a technical question then education is actually key. Hopefully it will be a deterrent more than anything," he said.

Education Minister Hekia Parata said the issue of the appropriateness of the question was an "operational matter" for NZQA to respond to.

Rohypnol can also be used for the short-term treatment of insomnia, as a pre-medication in surgical procedures, as an anticonvulsant to fight seizures and as an anxiolytic to relieve anxiety.