How many soliloquies are in Macbeth?Mention in which act and scene they occur.

There are seven (7) soliloquies in Macbeth, but one is a
short speech by Macbeth in Act II, Scene 3 in which Macbeth, who, although he enters
with Malcolm and Donalbain, seems to be talking to himself shortly after the murder of
Duncan:

Had I
but died an hour before this chance,
I had lived a blessed time; for from
this instant
There's nothing serious in mortality:
All is but
toys; renown and grace is dead;
The wine of life is drawn, and the mere
lees
Is left this vault to brag of.
(2.3.99-104)

While the other
speeches are clearly soliloquies as they are speeches delivered by one character alone
on the stage, a soliloquy, according to Dr. Wheeler, can be a speech in which a
character just believes that he is alone; so, in that case the above few lines qualify. 
Soliloquies are important because they provide otherwise inaccessible information to the
audience.  Often they offer sharp insights to the character who speaks, and they are
considered to be true reflections of what the speaker believes or feels.  Indeed, it is
through the soliloquies of Macbeth that the reader/audience learns that he is not all
evil.

Here, then, are the other six
soliloquies:

1. "Glamis thou art..."
   (1.5)


2. "The raven himself is hoarse..."  (1.5)   [These 2
   are Lady Macbeth's]


3. "If it were done...."
   (1.7)


4. "Is this a dagger...."
   (2.1)


5. "To be thus is
   nothing....(3.1)


6. She should have died hereafter
   (5.7)