Answer:
²⁵ Mg = 10.00%
²⁶ Mg = 11.0%
Explanation:
Given that:
Magnesium ²⁴Mg has an abundance of 78.99%
Hence, (100 - 78.99)% = 21.01%
21.01% is the abundance of ²⁵ Mg and ²⁶ Mg
Suppose,
²⁵ Mg = x
²⁶ Mg = (21.01 - x)%
Then;
avg. atomic mass = 
where the avg. atomic mass = 24.3050
∴
2430.5 = 2440.46915 -0.9968 x
0.9968x = 2440.46915 - 2430.5
0.9968x = 9.96915
x = 9.96915/0.9968
x = 10.00%
∴ Recall that:
²⁵ Mg = x
²⁶ Mg = (21.01 - x)%
²⁵ Mg = 10.00%
²⁶ Mg = (21.01 - 10.00)%
²⁶ Mg = 11.0%
Answer:
Mole fraction for solute = 0.1, or 10%
Molality = 6.24 mol/kg
Explanation:
22.3% by mass → In 100 g of solution, we have 22.3 g of HCOOH
Mass of solution = 100 g
Mass of solute = 22.3 g
Mass of solvent = 100 g - 22.3g = 77.7 g
Let's convert the mass to moles
22.3 g . 1mol/ 46 g = 0.485 moles
77.7 g. 1mol / 18 g = 4.32 moles
Total moles = 4.32 moles + 0.485 moles = 4.805 moles
Xm for solute = 0.485 / 4.805 = 0.100 → 10%
Molality → mol/ kg → we convert the mass of solvent to kg
77.7 g. 1 kg / 1000g = 0.0777 kg
0.485 mol / 0.0777 kg = 6.24 m
Global cooling was a hypothesis of the looming cooling of the Earth's surface and atmosphere that would take place over a period of substantial glaciation.
It emerged as a result of a drop of temperature during the period of 1940s and 1970s. After this it was realized that it is not a big threat as global warming.
On the other hand, Global warming is the rise in overall temperature of the atmosphere which is caused by greenhouse effect that is as a result of rise in the levels of greenhouse gas emissions such as CFCs and carbon dioxide.
Global warming is a present threat in the society world over with the rise in temperatures and climatic changes taking place, this is the reason why global warming replaced global cooling.
Answer:
eight oxygen atoms
Explanation:
This formula shows that in one mole of this compound, there are 3 moles of Ca atoms that combine with 2 moles of the PO4(phosphate) groups, which gives a total of 2 moles of P atoms and 8 moles of 0 atoms.
Ionic bond is characterized by the complete transfer of valence electrons between atoms. In this kind of bond, a metal loses its electron in order to become a cation while the nonmetal accept the electron resulting to an anion.
