Simple. The atomic number is the number of protons (12) and the mass number is the number of neutrons and protons combined. So you'd subtract 12 from 25 (25-12=) and that'd get you 13 as your answer. If you need to find the number of electrons, it'll be the same as the number of protons unless it has a certain charge and if it does, if it's positive it has more protons (+) than electrons (-), if it is negative it has more electrons (- negatively charged) than protons (+ positively charged)
Answer:
m = 0.5556 mol/kg
Explanation:
The molality of any solution is calculated using the following expression:
m = moles solute / kg solvent (1)
So in order to calculate the molality of this solution, we need to calculate the moles of the glucose using the expression:
n = mass / molecular weight (2)
The molecular weight of glucose, can be calculated using the molecular mass of the atoms in the glucose:
C = 12 g/mol; H = 1 g/mol; O = 16 g/mol
the molecular weight is:
MW = (12*6) + (12*1) + (6*16) = 180 g/mol
Then, the moles of glucose:
moles = 50 / 180 = 0.2778 moles
The solvent in this case is water, and 500 g of water is 0.5 kg of water, so the molality is:
m = 0.2778 / 0.5
m = 0.5556 mol/kg
Answer:
Hello! Your answer would be, D) HCI
Explanation:
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D. all of the above are evidence of a chemical reaction
A rule of thumb is that elements in the same column or "group" have similar chemical properties. Answer D. has four elements that are all in group 2, or the "alkaline earth metals". The answer is <span>D. 4, 20, 38, 88</span>