Answer:
1) Pecan tree 1 and Pecan tree 4
2) I don't know
Explanation:
The orbits of the planets are coplanar because during the Solar System's formation, the planets formed out of a disk of dust which surrounded the Sun. Because that disk of dust was a disk, all in a plane, all of the planets formed in a plane as well.
http://curious.astro.cornell.edu/about-us/57-our-solar-system/planets-and-dwarf-planets/orbits/242-why-do-all-the-planets-orbit-in-the-same-plane-intermediate
PH is the test of acidity or basicity of a solution. it follows the formula:
pH = pKa + log [salt] / [acid] where NaF is the salt and HF is the acid in this case.
By literature, Ka of HF is 3.5*10^-4
<span>pKa= -log(Ka)=</span><span> 3.46 </span>
<span>pH = pKa + log [NaF / [HF] </span>
4.05 = 3.46 + log [NaF / [HF]
log [NaF / [HF]<span> = 0.59
</span>
[NaF / [HF] = 3.89
<span>Sand dunes are formed from wind
movement. There needs to be a large amount of loose sand in an area with
hardly any vegetation, enough wind to move grains of sand and some kind
of obstacle to make the blowing sand lose its momentum and settle in a
new place</span>
Answer:
HF: hydrogen bond
Explanation:
The hydrogen bond is a type of interaction that is established between a molecule that presents hydrogen with another that presents an atom with a high electronegativity, such as oxygen, fluorine or nitrogen (O, F, N), joining covalently due to their opposite charges.
The hydrogen atom has a positive charge and is known as a donor atom. The oxygen, fluorine or nitrogen atom is the bond acceptor atom.
So:
<u><em>HF: hydrogen bond</em></u>