How can rescuers ensure that they are providing effective breaths when using a bag-mask device?

The correct answer for above statement is:

sometimes it is identified as Ambu bag or generically as a standard resuscitator or "self-inflating kit", is a hand-held tool generally practiced to give positive pressure oxygenating to victims who are not exhaling or not breathing satisfactorily.So by using it one can observe chest lift with the breath.

it's a nutrition food for pregnant mothers so they unborn child can get its nutrition that it needs to grow in to a healthy baby.

explanation:

and the mother is getting all of her nutrition and her calcium and vitamins .