Time interval between closing of AV valve and semilunar valves is :-0.3 sec0.5 sec 0.1 sec0.8 sec

The time interval between the closure of the atrioventricular (AV) valves and the semilunar valves is known as the isovolumetric contraction phase and is an important concept in cardiac physiology.

The answer to your question is typically around 0.05 to 0.1 seconds. This brief interval represents the time the heart is transitioning between the two phases of the cardiac cycle: from ventricular filling to ventricular contraction.

To summarize:

1. The AV valves close first, followed shortly by the semilunar valves.
2. The standard interval in a healthy heart is approximately 0.05 to 0.1 seconds.
3. Among the options you presented, 0.1 sec is the most accurate representation of this interval.

Thus, the final answer is: 0.1 sec.