Answer:
The universe is comprised of more than 75% of materials that are not visible and are often considered to be the dark matter. These are the baryonic matter that is formed due to the accumulation of protons, neutrons as well as electrons. They can be baryonic or non-baryonic type of matter. These dark matters are the substance that interconnects mostly by gravity along with some visible matter such as the stars and planets. These matters do not reflect light and they attract other matters, forming the major mass of the entire universe.
The pollutants released into the atmosphere cause local air pollution <span>. However, they also cause regional air pollution, as with huge plumes of smoke covering a large area, and acid rain. Beyond that, we are emitting such a high level of pollutants that they are causing serious global environmental problems: climate change and ozone depletion. The human race has become capable of affecting the atmosphere that encircles the Earth, and the very planet itself.</span>
Answer:
Coronaviruses are named for the crown-like spikes on their surface. There are four main sub-groupings of coronaviruses, known as alpha, beta, gamma, and delta.
Human coronaviruses were first identified in the mid-1960s. The seven coronaviruses that can infect people are:
Common human coronaviruses
229E (alpha coronavirus)
NL63 (alpha coronavirus)
OC43 (beta coronavirus)
HKU1 (beta coronavirus)
Other human
