Answer:
sorry don't know the answer but i really need the points sorry
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.
The six electrons in the outermost shell allow selenium to have a variety of valence numbers.
The valence of selenium depends on which compound it is in. Selenium is very similar to sulfur. It may have a valence of 6.
EXAMPLE:
selenium hexafluoride SeF6, selenium trioxide SeO3
May have 4;
example
selenium tetrafluoride SeF4, selenium dioxide SeO2
MAy have 2;
example
selenium difluoride SeF2, selenium dichloride SeCl2
and may have -2;
example
hydrogen selenide H2Se
By use of ideal gas equation PV= nRT where n is the number of moles,P = pressure, V = volume, R= gas constant (0.08206 L. atm/ mol.k) ant T is the temperature,
to calculate the number of moles(n) =PV/RT
convert ml to L, that is 200/1000= 0.2 L
convert mmHg to atm, that is 780mm hg x 1atm/ 760 mm hg= 1.026 atm
convert temperature to kelvin, that is 135 +273= 408 k
n is therefore= (0.2 x 1.026)/ ( 0.08206 x 408)= 6.129 x10^-3 moles
from avogadro constant 1moles = 6.02 x10^23 molecules what about 6 .129 x10^-3 moles
= ( 6.02 x10^23) x (6.129 x10^-3)/ 1mole = 3.69 x10^21 molecules
Answer:
B
Explanation:
FUN is not building block of matter.
