Q1: One positive pulse with t_w = 75 µs is applied to one of the inputs of an exclusive-OR circuit. A second positive pulse with t_w = 15 µs is applied to the other input beginning 20 µs after the leading edge of the first pulse. Which statement describes the output in relation to the inputs?

ANS:D - *The exclusive-OR output is a 20 s pulse followed by a 15 s pulse, followed by a 40 s pulse.

When both the input pulses are high or low X-OR output is low.but when one of the input is high and another is low or vice-verse output is high. In this problem for the first 20uS one input is high and another is low, so obviously out put is a high. for next 15uS both the input is high so output is low and for remaining 40uS(75-20-15) first input is still high and second one is low so output is high.