What is the number of moles of solute in 250 ml of a 0.4 m solution ?

Can someone me with 3 and 4 plz. this is for masteries test.

Pastoral farming is best described as a. a method of raising livestock and moving herds b. an african method of agriculture c. a method of cultivating crops on poor soils d. a common method of desert farming select the best answer from the choices provided a b c d

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