What does the enzyme acetylcholinesterase break down acetylcholine into?

The junction of two nerve fibres is called:

Alzheimer's disease in humans is associated with the deficiency of

The cause of death in a person bitten by a cobra is:

In $P$,the membranes of pre-synaptic and post-synaptic neurons are in very close proximity,whereas in $Q$,there is a space between the membranes of pre-synaptic and post-synaptic neurons.
$\quad\quad\quad P\quad\quad\quad Q$

The space between two adjoining neurons where the chemical transmitter is released is known as: