Why was it important to filter and degas the mobile phase and the samples? how is the "reversed-phase" hplc used here different from "normal-phase" with regard to stationary and mobile phases, and order of elution? mobile phase composition (a) if the mobile phase composition was changed from 65: 35: 1 (v/v/v) to 75: 25: 1 (v/v/v) water: methanol: acetic acid, how would the time of elution (expressed as retention time) for caffeine be changed, and why would it be changed? (b) what if it was changed from 65: 35: 1 (water: methanol: acetic acid) to 55: 45: 1? how would that change the retention time and why?

water is a polar molecule. a chemical bond is a force of attraction between atoms or ions. bonds form when atoms share or transfer valence electrons. atoms form chemical bonds to achieve a full outer energy level, which is the most stable arrangement of electrons. so, false

explanation:

in h2o molecule, two water molecules are bonded by a hydrogen bond but the bond between two h - o bonds within a water molecule are covalent. the greater the electronegativity difference, the more ionic the bond is. bonds that are partly ionic are called polar covalent bonds. nonpolar covalent bonds, with equal sharing of the bond electrons, arise when the electronegativities of the two atoms are equal.

yo