10. What procedure is safest to follow when using an open flame to heat the contents of a test tube that contains a flammable mixture?
O A. Cork the test tube and then heat it gently near the bottom only.
O D. Cork the test tube and place it in a beaker of water, then heat the water in the beaker.
C. Heat the open test tube gently near the bottom only.
O B. Place the open test tube in a beaker of water, then heat the water in the beaker.

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

Abaker touches a pie right after taking it out of the oven. which statement best explains why the pie feels hot?

Briefly explain the process of refining of petroleum.