DP Chemistry (first assessment 2025)

Test builder »

Question 21N.1A.HL.TZ0.12

Date	November 2021	Marks available	[Maximum mark: 1]	Reference code	21N.1A.HL.TZ0.12
Level	HL	Paper	1A	Time zone	TZ0
Command term	Deduce	Question number	12	Adapted from	N/A

12.

[Maximum mark: 1]

21N.1A.HL.TZ0.12

Which molecules contain two pi ( $π$ ) bonds?

I. HCN
II. H₂CO₃
III. H₂C₂O₄

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

[1]

Markscheme

B

Syllabus sections

Structure 2. Models of bonding and structure » Structure 2.2—The covalent model » Structure 2.2.15—Sigma bonds σ form by the head-on combination of atomic orbitals where the electron density is concentrated along the bond axis. Pi bonds π form by the lateral combination of p-orbitals where the electron density is concentrated on opposite sides of the bond axis. Deduce the presence of sigma bonds and pi bonds in molecules and ions.