Answer:
Water is least dense at 0°C (freezing point)
The majority of Earth's atmosphere contain 78% is nitrogen, The Nitrogen cycle is the geochemical cycle in which nitrogen is converted into multiple chemical forms. Nitrogen cycle occurs in terrestrial and marine ecosystem. Nitrogen can be converted through both biological and physical process. The processes that are involved in nitrogen cycle are fixation, ammonification, nitrification, and denitrification.
There is limited amount of nitrogen that is useful but <u>increase of fossil fuel combustion, use of artificial nitrogen fertilizer</u> have dramatically increased the amount of nitrogen in nitrogen cycle.
<span>As humans change the way we live on the planet, the way that nitrogen moves around the Earth also changes. Nitrogen atoms may seem small enough to be easily overlooked. We look right through the ones in the air, do we not? Yet recent changes in the nitrogen cycle are causing a very noticeable effect on natural environments and human health. Lakes are clogged with aquatic weeds. Dead zones have formed in areas of the oceans where animals can not survive. Air pollutants that contain nitrogen are decreasing air quality and greenhouse gases that contain nitrogen are becoming more common.</span>
What percent of potassium-40 remains undecayed in a rock that is 3.9 billion years old? The 3.9 billion year old rock has undergone three half-lives (3.9 divided by 1.3 = 3). After 3 half-lives, 12.5% of the potassium-40 remains undecayed.
