Floating Point Representation:

According to IEEE 754 Standard, Floating Points are represented in Generic 
form as follows:

(-1)^S  x (1+ Significand) x 2^(Exponent-Bias)
 
where S= 0 for +ve number
       = 1 for -ve number.
Significand is the number in normalized form.
Exponent is the power of 2 with bias of 127.

The one added to significand is an implicit one. This 1 therefore, 
allows the  value stored in the significand to go up from 23bits to 24bits.

single precision bits=
31 30----23    22---------0 


1) 0
As zero has no 1 in it. It is represented as all zeros in Exponent of 2
0 00000000 00000000000000000000000

2) 100 
100 in binary = 1100100
in normalized form it is= 1.100100 x 2^6
0 10000101 100100--------0
Note exponent = 127+6=133

3) 0.5
in binary= 0.1 = 1.0 x 2^-1
0 01111110 0000-----------0

4) 0.000005
= 5/1000000 = 1/200000=1/110000110101000000
=.0000000000000000010100111110001
=1.0100111110001 x 2^-18
=0 01101101 01001111100001....

5) 12000 
in binary = 10111011100000 = 1.0111011100000 x 2^13
0 10001100 0111011100------0

6) -387.53
in binary = 110000011.100001111010111
= 1.10000011100001111010111 x 2^8
1 10000111 10000011100001111010111

7) -12000
is just like 12000 
1 10001100 01110111000-----0