The number of pi bonds in C₄H₄ (cyclobutadiene) is:
In C₄H₄ (cyclobutadiene, CH=CH-CH=CH in a ring), there are 2 double bonds, each with 1 pi bond, totaling 2 pi bonds, plus 10 sigma bonds.
Ref: NCERT Class 11 Chemistry > Chapter 4: Chemical Bonding and Molecular Structure > Topic: Covalent Bonding - Bond Parameters and Polarity and Fajan's Rule
