Answer to Question 1
A diurnal tidal pattern is a tidal pattern with a single high tide and one low tide in one tidal cycle. By contrast, a semidiurnal tidal pattern is a pattern of one high and one low tide every 12 hours 25 minutes. The two high tides and low tides are of approximate equivalent tidal height each day. Mixed tides are similar to semidiurnal tides in that there are two high tides and two low tides per day, but the tides are not of equivalent tidal height. One high tide is higher than the other high tide and one low tide is lower than the other low tide.
Answer to Question 2
A