When the heart is at rest or relaxing it is called A. Diastole
B. Systole
C. Stroke Volume

Diastole is when the heart muscle relaxes. When the heart relaxes, the chambers of the heart fill with blood, and a person's blood pressure decreases

If it's a smaller child or infant, place one on the middle of the chest and on the child's back. (if it is a bigger child with enough room for two, place one on the upper right/your left of the chest, and one on the lower left/your right) the pads should never touch each other. 

The freezing point of the ice is lowered because of the rock salt which then allows the ice to observe heat from the ice cream mixture without it melting.