Answer: Hard
Explanation:
The upper part of the mantle is hard as it contains thick rock layers. The mantle's upper layer and the crust make up a brittle and rigid rock that's referred to as the Lithosphere.
The upper mantle starts below the Earth crust and then stops at the start of the lower mantle. We should note that the upper mantle results in the movement of the tectonic plates.
When humans burn fossil fuels, the stored carbon is released into the atmosphere as carbon dioxide. The carbon is then free to cycle through the Earth and can upset the natural balance of the carbon available, changing the way that processes occur on Earth.
Answer:
Explanation:
Here, a balance between attraction between nucleus and electrons, and electron-electron, and nuclei-nuclei repulsion play role.
All chemical bonds are formed by overlapping of orbitals. If the electronegativity of the two elements forming the bond is very different (elements from the 1st ,2nd groups with elements of 7th group) then ionic bond are formed. If the electronegativities are more similar, then overlapping is stronger, and covalent bonds are formed.
