During a job interview, can I ask about a specific disability or about a task that requires certain abilities that the candidate might not be able to do?
Most employers advertise job postings that include a description of the primary job functions. These should be tasks that are necessary to do the job. Be specific, so that you ensure all candidates have the qualifications you are seeking. For instance “lifting 22 kg boxes throughout an eight-hour shift”. Just like any candidate, a person with a disability applying for the job must be able to do the primary job functions.
You do not have the right to ask someone if they have a disability, or what their disability is. You can ask them if they require an accommodation.
You can ask a job candidate how they might approach the primary job functions. You could ask “this job requires you to lift multiple boxes 22 kg boxes throughout the day. Are you able to complete this task?”
Don’t make assumptions about what people are able to do, or not do. You can also ask a candidate how they might approach a task. Perhaps you are interviewing someone who appears to have limited dexterity and the job requires typing speed in order to complete the daily workload. You might ask “this job requires that you type approximately 120 wpm. How would you deal with this workload?”. They might be able to use a product such as Dragon Naturally Speaking, a speech recognition software to do the requisite keyboarding.