4. Protactinium-231 undergoes alpha decay as shown:
231 Pa → 4X + He
Enter the appropriate values for A and Z and the chemical symbol for
Х
A:
Z:
X:

Which metal exist in liquid state and can be cut with knife ?

As air becomes more dense, (select all that apply) o. air weighs less o. gas molecules are closer together o. air is colder o. air weighs more o. gas molecules are further apart o. air is hotter

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