1. "I go to a concert." This is correct grammatically but sounds a bit stilted. (I go, I do go, I am going all convey the same idea.
2. One would be more likely to say "She ate two pieces of toast."
3. They are both correct. "Her mother gives her soup" does say what it was served in = a bowl, a cup, etc. The other is more specific as to how the soup was served.
4. Sally is a girl's name.
5. The spelling is "laughed" for the past tense. Essentially they all mean someone made fun of Tom.
6. "upset" could be sad, not necessarily angry. Synonyms could be "distraught, emotionally disturbed, agitated, uncomfortable, nervous = depending upon the connotation you wish to convey.
In addition to a good dictionary, a thesaurus is a marvelous tool for synonyms, antonyms, etc.
1. What are you going to do tomorrow?
I'm going to a concert.
I am going to go to a concert.
I will go to a concert.
I go to a concert.
(Are all answers correct?)
The first and third answers are fine. The second and fourth are not completely incorrect, but are awkwardly phrased.
2. He ate a piece of toast.
He ate a slice of toast.
He ate a bit of toast.
(Are all the same and correct? Can we say "She ate two toasts."?)
They're fine. You would not say "two toasts" -- you'd say "two pieces of toast."
3. Her mother gives a hot soup.
Her mother gives her hot soup.
Her mother gives a bowl of hot soup.
(Which one is correct?)
Both answers are fine.
4. Is Sally a male name or a female name?
5. He made a fool of Tom.
He made fun of Tom.
He laughted at Tom.
He ridiculed Tom.
He derided Tom.
(Are all the same?)
All are basically the same. Be sure to correct the spelling of "laughed."
6. You look upset.
You look angry.
(Are both the same? What other adjectives can we use instead of 'upset'?)
They're not exactly the same. "Upset" can mean angry, or it can also mean flustered, confused, unsettled, and others. See http://thesaurus.reference.com/browse/upset