The whole point of asking the F/O questions he should be able to answer easily is to check that he is still 'in the loop', has a bit of capacity to spare to be able to acknowledge the simple questions thus ensuring that he is not getting/has not got overloaded and can safely continue to fly the aircraft whilst the captain sorts out the problems. If there are no or very wrong answers it is time for the captain to assume PF duties and give his F/O a break whilst he gets himself out of the 'tunnel'.