Final answer:
In the molecule H—C=C—C≡N, there is a total of three pi bonds; one from the double bond (C=C) and two from the triple bond (C≡N).
Step-by-step explanation:
The student has asked to identify the number of pi bonds in the molecule H—C=C—C≡N.
To answer the question, each type of bond present in the molecule needs to be considered. A single bond is a sigma bond (σ bond), and any additional bonds between the same two atoms are pi bonds (π bonds).
Looking at the provided structure, there is one double bond (C=C) which consists of one σ bond and one π bond. There is also a triple bond (C≡N) which consists of one σ bond and two π bonds. Therefore, the molecule has a total of three pi bonds (one from the double bond and two from the triple bond).