The Global Positioning System (GPS) works in conjuction with electronic collars to enable scientists to track endangered animals.
I don't know much about this, but probably the reason why your teacher circled 300k is because of what's in the photo below. If you couldn't tell from the photo, its because 300k isn't negative. Anyway this is my guess, based on my limited knowledge.
The correct answer is 12.2% BaO.
The solution is found by dividing the mass of the BaO, which is 25.8 grams, by the total mass of the solution, which is 212 grams, then multiplying it by 100 to get the percentage:
I am actually taking this test right now and I think it is Solid please let me know if I am correct
3.84 Kg of sodium chloride is needed to lower the freezing point of the water so that ice melts.
Explanation:
Data given:
mass of ice = 30 Kg
molar mass of NaCl = 58.5 grams/mole
ΔT(depression in freezing point) = 15.4 F or - 9.22 degrees
Kf = 1.86 degree C/ mole
Molality = ?
mass of NaCl =?
i = 2 (because NaCl breaks into 2 ions)
ΔT = iKfm equation 1
Depression in freezing point when ice melts, the temperature is 0 degrees so
the depression in temperature = 9.22 degrees
putting the values in the equation:
9.22 = 2 x 1.86 x x
mass = 3.84 kg of NaCl will be required to lower the freezing point of the water so that the ice melts.