Tech A says that the difference between stored pulse width and the actual pulse width required to keep the mixture at the correct ratio is called fuel trim. Tech B says that the long-term trim values can be positive or negative. Who is correct? A. Tech A

B. Tech B

C. Both A and B

D. Neither A nor B

Ahe-xe mixture containing a 0.75 mole fraction of helium is used for cooling electronics in an avionics application. at a temperature of 300 k and atmospheric pressure, calculate the mass fraction of helium and the mass density, molar concentration and molecular weight of the mixture. if the cooling capacity is 10 l, what is the mass of the coolant?