An inexperienced chemist adds too little boiling solvent to an impure sample of product and then leaves this mixture to cool. the crystals form with product coated onto impure crystals. that form are pure. do not form. form with impurities coated onto the pure crystals

Recrystallization of a solid is an experimental technique used to separate out impurities from a pure product using differential solubilities of the solids in a solvent at different temperatures. We chose a solvent in which the pure solid has lower solubility at low temperatures but is completely soluble at higher temperatures. The amount of solvent taken must be sufficient to completely dissolve the impure solid formed in a reaction. The impurities must be soluble in cold solvent, so that they can remain in solution after crystallization of pure compound.  When the amount of solvent is too little then we cannot achieve the separation of pure crystals as the pure solid crystallizes on the impurities.

So the correct answer will be the crystals form with product coated onto impure crystals

answer: i would say b.

explanation:

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms