A typical cold pack involves mixing a solid salt, such as ammonium nitrate, with water. In other words, the cold pack you might buy at a pharmacy to put on a sprained ankle is just a dissolution chemical reaction. This reaction must be:: a. Exothermic and spontaneous
b. Endothermic and spontaneous
с. Endothermic requiring work
d. Exothermic requiring work
e. Not enough information

What is the formula for the molecular compound nitrogen monoxide

Which statement about the stamps is correct?

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size