<span>When the surface layer was dug up, the permafrost was exposed. When the weather warmed, this exposed permafrost would have melted and become soggy, causing the ground underneath the tracks to shift.</span>
adaptations.
Natural selection leads to traits called adaptations, which improve an organisms ability to survive and reproduce.
Photothenysis disorder plants leafs dying
Answer and explanation;
-The hydrogen bonding in water is a a result of partial negative charge on the oxygen of one molecule which forms a hydrogen bond with the partial positive charge on the hydrogen of other molecules.
-When molecules of water are close to each other, their positive and negative regions are attracted to the oppositely-charged regions of nearby water molecules. This force of attraction is called a hydrogen bond. Each water molecule is hydrogen bonded to four others.
-This important property of hydrogen bond occurs in polar molecules such as water which contains weak, partial negative charge at one region of a molecule and also a partial positive charge elsewhere in the molecule.
