Answer:
1.62
Explanation:
From the given information:
number of moles of benzamide ![=\dfrac{70.4 \ g}{121.14 \ g/mol}](https://tex.z-dn.net/?f=%3D%5Cdfrac%7B70.4%20%5C%20g%7D%7B121.14%20%5C%20g%2Fmol%7D)
= 0.58 mole
The molality = ![\dfrac{mass \ of \ solute (i.e. \ benzamide )}{mass \ of \ solvent }](https://tex.z-dn.net/?f=%5Cdfrac%7Bmass%20%5C%20of%20%5C%20solute%20%28i.e.%20%5C%20benzamide%20%29%7D%7Bmass%20%5C%20of%20%5C%20solvent%20%20%7D)
![= \dfrac{0.58 }{0.85 }](https://tex.z-dn.net/?f=%3D%20%5Cdfrac%7B0.58%20%7D%7B0.85%20%7D)
= 0.6837
Using the formula:
![\mathbf {dT = l \times k_f \times m}](https://tex.z-dn.net/?f=%5Cmathbf%20%7BdT%20%20%3D%20l%20%20%20%5Ctimes%20%20k_f%20%20%5Ctimes%20m%7D)
where;
dT = freezing point = 27
l = Van't Hoff factor = 1
kf = freezing constant of the solvent
∴
2.7 °C = 1 × kf × 0.6837 m
kf = 2.7 °C/ 0.6837m
kf = 3.949 °C/m
number of moles of NH4Cl = ![\dfrac{70.4 \ g}{53.491 \ g /mol}](https://tex.z-dn.net/?f=%5Cdfrac%7B70.4%20%5C%20g%7D%7B53.491%20%5C%20%20g%20%2Fmol%7D)
= 1.316 mol
The molality = ![\dfrac{1.316 \ mol}{0.85 \ kg}](https://tex.z-dn.net/?f=%5Cdfrac%7B1.316%20%5C%20mol%7D%7B0.85%20%5C%20kg%7D)
= 1.5484
Thus;
the above kf value is used in determining the Van't Hoff factor for NH4Cl
i.e.
9.9 = l × 3.949 × 1.5484 m
![l = \dfrac{9.9}{3.949 \times 1.5484 \ m}](https://tex.z-dn.net/?f=l%20%3D%20%5Cdfrac%7B9.9%7D%7B3.949%20%5Ctimes%201.5484%20%5C%20m%7D)
l = 1.62
MgBr2(aq) is an ionic compound which will have the releasing of 2 Br⁻ ions ions in water for every molecule of MgBr2 that dissolves.
MgBr2(s) --> Mg+(aq) + 2 Br⁻(aq)
[Br⁻] = 0.065 mol MgBr2/1L × 2 mol Br⁻ / 1 mol MgBr2 = 0.13 M
The answer to this question is [Br⁻] = 0.13 M
<span>You can answer this question by getting the atomic number and atomic mass of Oxygen from a periodic table. There you will find that the atomic number is 8, that means, by definition, that it has 8 protons. This is, because atomic number is defined as the number of protons of an element. Given that the atom is neutral, that implies that the atoms have the same number of electrons than protons. So you already know that the oxygen atoms has 8 protons and 8 electrons. The number of neutrons can vary, which is what defines the isotopes. Given that the atomic mass of oxygen is 15.999, that means that most atoms of oxygen has 8 neutrons (8 protons +8 neutrons = 16 atomic mass). But you can not be sure that a specific atom of oxygen has 8 neutrons, nevertheless, given that the other options are discarded (because they do not have 8 protons and 8 electrons), the only correct answer is the option A. 8 protons, 8 electrons, and 8 neutrons.</span>
8 tablets. To get 1 gram you would have to give 2 tablets every 6 hours. In 24 hours you would give 8 tablets (500 mg = .5 grams)