Can impulses pass in 2 directions across a synapse?

No, impulses cannot pass in two directions across a synapse. Synapses are unidirectional, meaning that impulses can only pass from the presynaptic neuron to the postsynaptic neuron. This is due to the way that synapses are structured. The presynaptic neuron releases neurotransmitters into the synaptic cleft, which is the space between the two neurons. These neurotransmitters bind to receptors on the postsynaptic neuron, which causes an electrical signal to be generated in the postsynaptic neuron. This electrical signal is then transmitted down the postsynaptic neuron.