What type of reaction is the formation of aldol from aldehyde?

What is the product formed when cumene is air oxidised in presence of Co-naphthenate and further treated with dilute acid?

Identify compound $$\mathrm{A}$$ in following reaction

Benzene + Ozone (excess) $$\rightarrow$$ Benzenetriozonide $$\xrightarrow{\mathrm{A}}$$ Glyoxal

Which of the following aldehydes is less reactive towards nucleophilic addition reaction?