Please help asap only need the answer for question 2 !!​

An atom of which element reacts with an atom of hydrogen to form a bond with the greatest degree of polarity ?

In a heat engine of 1000 j of heat enters the system and the piston does 500 j of work what is the final internal energy of the system if the inital energy was 2000 j we have to do all of these down here 1)write the equation 2)list out your know variables 3)plug the numbers into the equations 4)solve 5)write your solution statemtn that includes inital energuy and final energuy added

Do polar molecules have ionic bonds?