Synapses store

The pre-synaptic part is:

Where are synaptic vesicles found?

Which of the following statements is correct regarding electrical synapses?
$I.$ Pre and postsynaptic membranes are in very close proximity at electrical synapses.
$II.$ Electric currents are involved in the transmission of impulses.
$III.$ Transmission of an impulse across electrical synapses is very similar to impulse conduction along a single axon.
$IV.$ Impulse transmission is always faster in electrical synapses than across chemical synapses.
$V.$ Electrical synapses are rare in our system.
The correct option is:

Chemicals which are released at the synaptic junction are called

Which chemical substance is responsible for the transmission of nerve impulses across the synapse from one neuron to another?