Yes, "Give Sam a hand for his effort" is an imperative sentence. It issues a command or request, instructing someone to take action. Imperative sentences often begin with a verb and may or may not include a subject, which is typically implied. In this case, the subject "you" is understood as the one being addressed.
An imperative sentence is a sentence that gives a command. An example of an imperative sentence would be: Hand me those pamphlets, please.
"give forth" and "hand over" are both imperative statements demanding that you give someone something. For example, "Hand over the papers" means "give me the papers".
Imperative sentences give commands. Some examples of an imperative sentence would be: Turn down the radio. Watch for the boat. Walk to the front of the building.
"Give me your hand," she said. This is dialogue and must use quotes.
'Give me a hand lifting this table please?' asked Mike.
"Give me your hand," she said.
Hand that chocolate to me now!
There are no quotation marks in that sentence unless you state who's saying it. "Give me your hand", said Mary, would be correct.
The teacher *is writing* on the chalkboard.
dont bite the hand that feeds you
yes she flinched as he raised him hand to touch her.
At last! An atlas! Please hand me the atlas.