Hydrogen bonds<span> hold the paired nitrogenous bases together. Because </span>hydrogen bonds<span> are weak </span>bonds<span>, the two strands of </span>DNA<span> are easily separated a characteristic that is important to </span>DNA's<span> function.</span>Hydrogen bonds<span> form between adenine and thymine and between cytosine and guanine.</span>
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Covalent solids, also called network solids, are solids that are held together by covalent bonds. As such, they need localized electrons (shared between the atoms) and therefore the atoms are arranged in fixed geometries. Distortion far from this geometry can only occur through a breaking of covalent sigma bonds.
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Explanation:
Air pollutants also affect the biosphere in turn. Ozone and acid deposition suppress plant growth; meanwhile, aerosols and their indirect effects on clouds decrease total photosynthetically active radiation (PAR) while increasing the diffuse fraction.
There are four type of intermolecular forces: ionic, dipole-dipole, hydrogen bonds and London disperssion forces.
CH4 have no ions, so there are not ionic forces.
CH4 is a symetrical molecule, so there cannot be a net dipole in the molecule, so there is not dipole-dipole interaction.
Hydrogen bonding is only possbile when H is bonded to N, O or F, beacuse they are the atoms that considerable higher electgronegativy than hydrogen.
So, the only intermolecular force present in CH4 molecules is London disperssion forces, which is a force present in any molecule and is the weakiest one. That explains the low melting and boiling points of CH4.