Question

Which of the following statements is false?

• A. HCl molecule has one sigma bond
• B. Acetylene molecule has three pi bonds and three sigma bonds
• C. Ethylene molecule has five sigma bonds and one pi bond
• D. Water molecule has two sigma bonds and two lone pairs

Answer 1

Answer: (B)

Here
Acetylene molecule has $3\sigma $ bonds and $2\pi $ bonds.
H-Cl has only one sigma bond so it is correct.
In water there are 2 sigma bond and 2 lp electrons so it is also correct.

Ethylene has also 5 sigma and one pi bonds so it is also correct.