I think the answer is B. static charge. I hope this helps! :)
Answer:
The elements are arranged in seven horizontal rows, called periods or series, and 18 vertical columns, called groups.
Explanation:
Answer:
The attractive force is negative and MgO has a higher melting point
Explanation:
From Couloumb's law:
Energy of interaction, E = k 
where q1 and q2 are the charges of the ions, k is Coulomb's constant and r is the distance between both ions, i.e the atomic radii of the ions.
If you look at Coulomb's law, you note that in the force is negative (because q1 is negative while q2 is positive).
In addition to that, the compounds MgO and NaF have similar combined ionic radii, then we can determine the melting point trend from the amount of energy gotten
The melting point of ionic compounds is determined by 1. charge on the ions 2. size of ions. while NaF has smaller charges (+1 and -1), MgO (+2 and -2) has larger charges and greater combined atomic radii. This implies that the compound with greater force would have a higher melting point.
Hence the compound MgO would have a higher melting point than NaF.
In order to decrease the chances of deception in acquiring a handwriting sample, what the law enforcement do is that, they ask they person to write as little as possible, write the passage only once and also gather the material that consist some of the similar words and phrases as the suspected document. Answer for this would be all of the above.