What is race problem?

Answer 1

Race-around condition is arises in level triggered JK flip flop . when you apply 1 to both j and k input than the flip flop will toggle on every clock or it may toggle multiple times in the same clock pulse . it may be possible that new output will feedback to input before clock goes to zero (for positive edge triggered) if it happens than the flip flop will toggle on time again . this undesired toggling is called Race-around condition.

overcome by -

using edge triggered flip flop.

using very narrow clock width.