Write a function called echo that takes as argument a list and returns a copy of that listwith each element duplicated right after it. here are some examples of how your program should behave on python idle. > > > echo(['a','b','c'])['a', 'a', 'b', 'b', 'c', 'c']> > > echo(['x','y'])['x', 'x', 'y', 'y']> > > echo([85, 72, 61])[85, 85, 72, 72, 61, 61]> > > echo([85, "abc", 6.79])[85, 85, 'abc', 'abc', 6.79, 6.79]

The temperature of air decreases as it is compressed by an adiabatic compressor. a)- true b)- false

Adouble-strand no. 60 roller chain is used to transmit power between a 13-tooth driving sprocket rotating at 300 rev/min and a 52-tooth driven sprocket. a) what is the allowable horsepower of this drive? b) estimate the center-to-center distance if the chain length is 82 pitches. c) estimate the torque and bending force on the driving shaft by the chain if the actual horsepower transmitted is 30 percent less than the corrected (allowable) power.

Avolume of 2.65 m3 of air in a rigid, insulated container fitted with a paddle wheel is initially at 264 k, 5.6 bar. the air receives 432 kj by work from the paddle wheel. assuming the ideal gas model with cv = 0.71 kj/kg • k, determine for the air the amount of entropy produced, in kj/k