For practice I need to answer the following questions:

(h) (2 points) Explain at least two reasons why delaying the spark timing to later times in an internal combustion engine can help reduce NO emissions. (h) (1 point) Why is it advantageous to use selective catalytic reduction instead of selective noncatalytic reduction to remove NO from the exhaust of combustion devices. (j) (1 point) How do unburned hydrocarbons survive into the exhaust of a spark ignition engine operating at fuel lean combustion conditions? (k) (1 point) If an emissions measurement is conducted on a wet basis, this means that the water is first condensed out into a liquid prior to the measurement (True/False)