$4\mathrm{.}1$ For the tree in Figure $4\mathrm{.}74$: a$.$ Which node is the root? b$.$ Which nodes are leaves?

$4\mathrm{.}2$ For each node in the tree of Figure $4\mathrm{.}74$: a$.$ Name the parent node. b$.$ List the children. c$.$ List the siblings. d$.$ Compute the depth. e$.$ Compute the height.

$4\mathrm{.}3$ What is the depth of the tree in Figure $4\mathrm{.}74?4\mathrm{.}4$ Show that in a binary tree of N nodes, there are N $+1$ nullptr links representing children.