How many grams of o2(g) are needed to completely burn 64.3 g of c3h8(g)?

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

Which actions would increase the rate at salt dissolves in water? stir the water? crush the salt? use less water? heat the water? cool the salt

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?