Which of the following is an example of convection?

a. hot air rising and cooler air falling
b. a hot oven warming the air around it
c. the rays of the sun warming the earth
d. a hot object transferring heat to a cooler one

p. s. this is science

Several processes form metal ore. match each process to its description. volcanic activity weathering hydrothermal energy rocks break down as they interact with air and water. arrowright density differences and other factors cause metals to concentrate in igneous rocks. arrowright seawater heats up from contact with hot rock, and metals dissolve in it. the water rises and contacts cooler water, causing metal ores to settle on the ocean floor. arrowright

An object has a weight of 500 on earth what is the mass of this object

If a balloon is taken outside on a very cold day, what will occur?