Zinc is a pure substance. How could you make a mixture from a 1.0-g zinc disc?
A) Place the disc in a beaker with 200 mL of sulfuric acid.
B)Divide the disc into 5 small pieces.
C)Compress the disc into a flatter shape.
D)Coat the disc with another pure substance, such as copper.

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

If 22.5 liters of oxygen reacted with excess of hydrogen, how many liters of water vapor could be produced?

Alidded glass container is filled with a colored gas. after a period of time, it is observed that the gas is uniformly spread throughout the box and that the movement has slowed considerably. next, a warm iron plate is carefully placed under the box. why is there resumed movement of the gas in the container?