PLS HELP I NEED ATLEAST 1-2 SENTENCES!!

When at a point two solid phase changes to one solid phase on cooling then it is known as a) eutectoid point b) eutectic point c) peritectic point d) peritectoid point

Most leaks in reciprocating air compressors can be detected and minimized by: (clo4) a)-detecting leakage areas using ultrasonic acoustic detector. b)-tightening joints and connections c)-replacing faulty equipment d)-all of the given options

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?