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.
The given question is incomplete. The complete question is :
Welding is an industrial process that is used to join pieces of metal. A certain mixture of gases used in welding is composed of carbon dioxide and argon. The partial pressure of carbon dioxide is 0.080 atm and the partial pressure of argon is 0.24 atm. What is the total pressure of the mixture.
Answer: 0.32 atm
Explanation:
According to Dalton's law, the total pressure is the sum of individual pressures.

Given :
=total pressure of gases = ?
= partial pressure of carbon dioxide = 0.080 atm
= partial pressure of argon = 0.24 atm
putting in the values we get:
Thus the total pressure of the gases is 0.32 atm
answer is compound i think
Explanation: