<span>Correct answer is : 72.0 g/mole
If we assume Ideal Gas Law, PV = nRT. n = PV/RT = ((0.988 atm)*(0.258 L))/((0.0821 L*atm/mole*K)*(100 + 273.15)) = 0.00832 moles
Molar mass = 0.599 g/0.00832 moles = 72.0 g/mole; your answer is E.</span>
We have been given the OH⁻ ion concentration, we can calculate the pOH concentration.
pOH = -log [OH⁻]
pOH = - log (5.5 x 10⁻⁵ M)
pOH = 4.26
we can then calculate the pH value
pH + pOH = 14
pH = 14 - 4.26
pH = 9.74
since pH > 7 the solution is basic.
by knowing the pH value, we can calculate the H₃O⁺ concentration
pH = - log[H₃O⁺]
[H₃O⁺] = antilog (-pH) = antilog (-9.74)
[H₃O⁺] = 1.82 x 10⁻¹⁰ M
The mould and cast fossil is Option B.
The carbon film fossil is Option C.
The Amber fossil is Option A.
The ice fossil is Option D.
<h3><u>Explanation:</u></h3>
Mould and cast fossils are formed when an organism or any organic object gets buried inside sediment and gets decomposed off, leaving an empty space between the sediments which are occupied by different minerals like carbon, calcium, silica etc. Thus, this mineral takes the shape of that decomposed object and stays for years.
The carbon film fossils are those fossils which take long time to form and are difficult to recover as well. They are formed when some organic substance gets very deep into Earth's surface and gets burned by the interior lava into only a thin layer of carbon.
The amber fossils are very common which are formed when the living organisms get stuck in plant resins and dies, which are enclosed into the plant's resin and are recovered thousands of years after.
The ice fossils aren't actually fossil because in very cold regions, the dead bodies often don't decompose but remain as it is for years. Thus the soft tissues are also recoverable after many years.
Here's what I got:
microscope
hope you get an A friend!!
Answer:
7.44x10⁻³ mol/L and 744 ppm
Explanation:
Let's assume that the hardness of the water is totally from Ca⁺² ions only(the hardness is the measure of Ca⁺² and Mg⁺² ions). The titration with EDTA will form a complex. The EDTA is always in 1:1 proportion, so the number of moles of it will be the number of moles of Ca⁺², which will be the number of moles of CaCO₃.
n = 0.0124 L * 0.0300 mol/L
n = 3.72x10⁻⁴ mol
The molarity is the number of moles divided by the volume (0.05 L)
M = 3.72x10⁻⁴/0.05
M = 7.44x10⁻³ mol/L
1 part per million = 1 mg/L. The molar mass of the CaCO₃ is 100 g/mol, so the mass of it is:
m = 3.72x10⁻⁴ mol * 100 g/mol
m = 0.0372 g = 37.2 mg
Then, the ppm:
37.2/0.05 = 744 ppm