D.4s this would be the answer because after eight electrons are added to the third orbital two have to be added to the fourth before more can be added to the third one. The third orbital can hold 18 electrons, but it first has to have eight, then two on the fourth orbital, then the rest of the ten can be added

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499 mg sample of CuSO4. xH2O is heated and reweighed to give a mass of 319 mg. Given that the sample contains 2 mmol of Cu; what

nevsk [136]

The value of x in CuSO4. xH2O is 5.

Given that;

Number of moles of anhydrous salt = Number of moles of hydrated salt

Number of moles of anhydrous salt = 319 × $10^-3$

Mass of hydrated salt = 499 × $10^-3$ g

Number of moles of anhydrous salt = 319 $10^-3$ g/160 g/mol = 0.00199 moles

Number of moles of hydrated salt = 499 × $10^-3$ g/ 160 + 18x

0.00199 = 499 × $10^-3$ g/ 160 + 18x

0.00199 (160 + 18x) = 499 × $10^-3$

0.318 + 0.036x = 0.499

0.036x = 0.499 - 0.318

0.036x = 0.181

x = 0.181/0.036

x = 5

Hence, x in CuSO4. xH2O is 5.

Learn more: brainly.com/question/9743981

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