I understand preposition "in" has the meaning of during a period of time.
1. I phoned you in the morning.
I also understand preposition "on" has the meaning of indicating when sth happens. for example:
2. My birthday is on Tuesday.
I also know I must use "on" in the sentence below.
3. I phoned you on Tuesday morning.
Can I say "I phoned you in Tuesday morning." because I phoned you really during Tuesday morning.
(really during the part of that period.)
I am much obliged to you for your help.