Which of the following is improper isotope notation? Explanation: Nineteen is potassium's atomic number A. k-39
B. All are correct
C. Potassium-19
D. Potassium-39

C. Potassium-19 .

Explanation:

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In this case, since isotopes are known be atoms of the same element with equal atomic number but different mass number, we can consider the case of carbon which has two natural occurring ones, carbon-12 and carbon-13 whereas carbon-12 has the greatest abundance. However, isotope notation may take two forms:

1. Symbol of the element followed by a dash indicating the mass number of the isotope, for instance: C-12, K-39, and so on.

2. Name of the element followed by a dash indicating the mass number of the isotope, for instance: Carbon-12, Potassium-39, and so on.

In such a way, the improper isotope notation is C. Potassium-19 , considering that A should be K-39 because atomic symbol of potassium is K, not k.

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"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"