What chemical property of diesel fuel is measured by the Cetane Number, and how does it affect combustion?

1. It measures fuel viscosity, which determines how fast fuel flows through the filters.
2. It measures ignition delay; a higher cetane number indicates a shorter ignition delay and smoother start.
3. It measures fuel volatility, which indicates the temperature at which the fuel evaporates.
4. It measures sulfur content; high cetane prevents acid formation.