5)
the circit should work at night as, the ldr will dawf the other resistor

the circit will not work at day as the ldr is still 400 OHM's which is
higher than the 100 OHM resistor

because the bulb has a resistance of 100 OHM's it will not work as expected

this will cause the bulb to never be properly on as the resistance in the bulbs branch
will limit the voltage through it to be <100 OHM's and thus it wont get 6V over it

to fix this a voltage follower can be place between the bulb and the potential divider
to keep the impedances at the right locations

(see book for details)
6)a)i) in book
6)a)ii) in book
6)a)iii) when the switch is releases the voltage over the capacitor will be at 8.65 V
this will mean the led is on.
when it falls to 6V the capacitor will make the logic gate switch 3.34 seconds after the switch 
is released, this will cause the not gate to switch and the led to be on
6)b)i) in book
6)b)ii) in book

7)a) in book
7)b)i) in book
7)b)ii) in book
7)b)iii) in book
7)b)iv) in book
7)b)v) in book

8)a) in book
8b) in book
8)c)i) because it has a higher input imedance
8)c)ii) in book
8)c)iii) in book
8)d)i) in book
8)d)ii) to smooth the signal of noise
8)d)iii) in book
8)d)e) in book