A planetary surface is where the solid (or liquid) material of the outer crust on certain types of astronomical objects contacts the atmosphere or outer space. Planetary surfaces are found on solid objects of planetary mass, including terrestrial planets (including Earth), dwarf planets, natural satellites, planetesimals and many other small Solar System bodies (SSSBs).[1][2][3] The study of planetary surfaces is a field of planetary geology known as surface geology, but also a focus of a number of fields including planetary cartography, topography, geomorphology, atmospheric sciences, and astronomy. Land (or ground) is the term given to non-liquid planetary surfaces. The term landing is used to describe the collision of an object with a planetary surface and is usually at a velocity in which the object can remain intact and remain attached.
In differentiated bodies, the surface is where the crust meets the planetary boundary layer. Anything below this is regarded as being sub-surface or sub-marine. Most bodies more massive than super-Earths, including stars and gas giants, as well as smaller gas dwarfs, transition contiguously between phases, including gas, liquid, and solid. As such, they are generally regarded as lacking surfaces.
Planetary surfaces and surface life are of particular interest to humans as it is the primary habitat of the species, which has evolved to move over land and breathe air. Human space exploration and space colonization therefore focuses heavily on them. Humans have only directly explored the surface of Earth and the Moon. The vast distances and complexities of space makes direct exploration of even near-Earth objects dangerous and expensive. As such, all other exploration has been indirect via space probes.
Indirect observations by flyby or orbit currently provide insufficient information to confirm the composition and properties of planetary surfaces. Much of what is known is from the use of techniques such as astronomical spectroscopy and sample return. Lander spacecraft have explored the surfaces of planets Mars and Venus. Mars is the only other planet to have had its surface explored by a mobile surface probe (rover). Titan is the only non-planetary object of planetary mass to have been explored by lander. Landers have explored several smaller bodies including 433 Eros (2001), 25143 Itokawa (2005), Tempel 1 (2005), 67P/Churyumov–Gerasimenko (2014), 162173 Ryugu (2018) and 101955 Bennu (2020). Surface samples have been collected from the Moon (returned 1969), 25143 Itokawa (returned 2010), 162173 Ryugu and 101955 Bennu.
(1) Fewer microorganisms will grow on the surface of the lake if iron compounds are added to a lake with an overabundance of nutrients. Hence, option 1 is correct.
(2) Fracking means using water and chemicals at high pressure to open up fissures to access oil and gas resources. Hence, option 2 is correct.
<h3>What are microorganisms?</h3>
An organism that can be seen only through a microscope.
Iron is a natural capping agent which can enhance sediment P binding capacity, thus reducing P availability and shifting a lake from an algal to a macrophyte dominated state. Iron could, however, also impose toxic effects on the biota.
Fracking is the injection of a fluid at high pressure into an underground rock formation to open fissures and allow trapped gas or crude oil to flow through a pipe to a wellhead at the surface.
This technique is used in natural gas and petroleum production.
1) Fewer microorganisms will grow on the surface of the lake if iron compounds are added to a lake with an overabundance of nutrients. Hence, option 1 is correct.
(2) Fracking means using water and chemicals at high pressure to open up fissures to access oil and gas resources. Hence, option 2 is correct
Learn more about the microorganisms here:
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<em>Answer:</em>
- The atom have a full valence electron shell.
<em>Explanation:</em>
- My question is that why covalent bonds take place?
Every atoms tends to from bond with another atoms in order to get nearest electronic configuration of nobel gases. They become stable when their valence shell become complete. So when covelant bond forms between atoms, share electrons to each other and stabilize themselves.
Answer:
See explanation below
Explanation:
The question is incomplete. However in picture 1, you have the starting materials and the structure of the product, which you miss in this part.
Now, in picture 2, you have the starting reactant and the product, and the mechanism that is taking place here.
First, all what we have here is an acid base reaction. In the first step, we are using the acid medium to convert the reactant into an alcohol. The bromine there, is not leaving the molecule yet, because it's neccesary for the next step. The starting reactant is an alkene, in that way, we can convert the reactant in the first step into a secondary alcohol. In other words, the first reaction is a alkene hydration.
In the second step, we use a strong base. You may say this is a strong nucleophile and will do a Sn2 reaction to form another alcohol there, but it's not the case, because, before any kind of reaction happens, the priority here is always the acid base, so the base will react with the acidic hydrogen. In this case, it will substract an hydrogen from the OH. When this happens, the lone pair will do an auto condensation here, and attacks the bromine in the molecule. In this way, the molecule will become a cyclomolecule, and that way it form the final product.
See picture 2, for mechanism
