The answer is b. radon-222. The alpha decay means that it will emit an alpha particle when decays. The alpha particle has two protons and two neutrons. So Radium(88) minus two protons will become Radon(86). And the atomic mass will become 226-4=222.
The answer is in the attachment below:
The appropriate answer is b. greenhouse gases. Greenhouse gases such as carbon dioxide and methane have the ability to trap infrared radiation or heat in the atmosphere. Without these gases the Earth would be thirty degrees cooler than it is today. Pollution today has caused more of these gases to enter the atmosphere and this is the main cause of contemporary global warming.
Ozone in the stratosphere actually blocks another form of radiation called ultraviolet radiation. Geothermal energy is derived from hot rocks inside the earth.
D)Universe, galaxy, solar system, moon
