a + b + ⋯ + g ⏟ 4 π {\displaystyle \underbrace {a+b+\cdots +g} _{4\pi }}
en:1669_eruption_of_Mount_Etna sin30°=0.5 CO 2 + C ⟶ 2 CO {\displaystyle {\ce {CO2 + C -> 2 CO}}}
