<span>The roman numeral 3 represents the oxidation of the metal, scandium. </span>
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.
Y=15 x=60
•1/3 •1/3
y=5 x=45
When ammonium chloride NH4Cl is added to water and stirred, it dissolves spontaneously (this is the basis for ΔG) for and the resulting solution feels cold (endothermic, the basis for ΔH). Without doing any calculations, we can easily deduce the signs of ΔG, ΔH, and ΔS for this process based on the observations.
ΔG < 0 (it is spontaneous)
ΔH < 0 (because the process is endothermic - it absorbs energy)
ΔS > 0 (entropy increases because of the dissolution of NH4Cl in water
The number of particles in 46g of Sodium (Na) atoms are 2.00088735004 mol