Astudent records the temperature of a mixture of ice and rubbing alcohol as -3.8 k. is this a valid measurement? explain your answer.

No it is not a valid observation as the lowest temperature that can be achieved is 0 K.

a temperature below 0 K is practically not possible hence based on reported temperature of a mixture of ice and rubbing alcohol it can be said that this is not a correct measurement.

So it is suggested that student should repeat the experiment.

c. because step up transformer steps up the input voltage i.e increases the input voltage  

the number of turns are greater on the secondary side of step up transformer  

transformer does not handle dc current