Chemical, there is a chemical change whenever the bleach is put on the stain or anything else.
Answer:
Ca:
Explanation:
A Lewis structure shows the number of valence electrons about an atom.
Ca is in Group 2 of Period 4.
Its electron configuration is [Ar]4s².
Thus, Ca has two valence electrons and its Lewis structure is Ca:
Because this acid dissolves the enamel on the tooth creating holes or cavities
Pretty sure the answer is c but not completely positive !
All you have to do is research more about this scientist´s theory. Just google: Why wasn´t Wegner´s hypothesis accepted?
Trust me, the answers are there.<span>
</span>Next time just research it.
Wegner´s idea seemed so ridiculous at the time that he was ridiculed by other scientists. The problem was that to his colleagues there seemed no plausible mechanism for how the continents could move through the oceans.
