Making repeated separations of the various substances in the pitchblende, Marie and Pierre used the Curie electrometer to identify the most radioactive fractions. They thus discovered that two fractions, one containing mostly bismuth and the other containing mostly barium, were strongly radioactive.
<h3>What was surprising about pitchblende?</h3>
Since it was no longer appropriate to call them “uranic rays,” Marie proposed a new name: “radioactivity.”
Even more surprising, Marie next found that a uranium ore called pitchblende contained two powerfully radioactive new elements: polonium, which she named for her native Poland, and radium.
<h3>Why is radium more radioactive than uranium?</h3>
It is 2.7 million times more radioactive than the same molar amount of natural uranium (mostly uranium-238), due to its proportionally shorter half-life.
Learn more about highly radioactive elements here:
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brainly.com/question/10257016</h3><h3 /><h3>#SPJ4</h3>
Answer:
a) The concentration of drug in the bottle is 9.8 mg/ml
b) 0.15 ml drug solution + 1.85 ml saline.
c) 4.9 × 10⁻⁵ mol/l
Explanation:
Hi there!
a) The concentration of the drug in the bottle is 294 mg/ 30.0 ml = 9.8 mg/ml
b) The drug has to be administrated at a dose of 0.0210 mg/ kg body mass. Then, the total mass of drug that there should be in the injection for a person of 70 kg will be:
0.0210 mg/kg-body mass * 70 kg = 1.47 mg drug.
The volume of solution that contains that mass of drug can be calculated using the value of the concentration calculated in a)
If 9.8 mg of the drug is contained in 1 ml of solution, then 1.47 mg drug will be present in (1.47 mg * 1 ml/ 9.8 mg) 0.15 ml.
To prepare the injection, you should take 0.15 ml of the concentrated drug solution and (2.0 ml - 0.15 ml) 1.85 ml saline
c) In the injection there is a concentration of (1.47 mg / 2.0 ml) 0.735 mg/ml.
Let´s convert it to molarity:
0.735 mg/ml * 1000 ml/l * 0.001 g/mg* 1 mol/ 15000 g = 4.9 × 10⁻⁵ mol/l
Answer: It is usually separated from tea leaves by filtration. B Because the composition of the solution is uniform throughout, it is a homogeneous mixture. A Orange juice contains particles of solid (pulp) as well as liquid; it is not chemically pure.
The answer is (2) higher vapor pressure and weaker intermolecular forces. Propanone has a lower boiling point, so it is more volatile than water. Propanone's vapor pressure is, therefore, higher than that of water at 50 degrees Celsius. Propanone is more volatile due to the fact that the intermolecular forces that hold its molecuels together are not as strong as those that hold together molecules of water. Since the IMFs are weaker, it takes less thermal energy to break individual molecules free of each other.
Answer:
Mass = 11 g
Explanation:
Given data:
Mass of Zn = 5 g
Mass of HCl = 50 g
Mass of hydrogen gas produced = 6 g
Mass of zinc chloride produced = ?
Solution:
Chemical equation:
Zn + 2HCl → ZnCl₂ + H₂
Number of moles of Zn:
Number of moles = mass / molar mass
Number of moles = 5 g / 65.38 g/mol
Number of moles = 0.08 mol
Number of moles of HCl :
Number of moles = mass / molar mass
Number of moles = 50 g / 36.5 g/mol
Number of moles = 1.4 mol
Now we will compare the moles of both reactant with zinc chloride.
Zn : ZnCl₂
1 : 1
0.08 : 0.08
HCl : ZnCl₂
2 : 1
1.4 : 1/2×1.4 =0.7 mol
The number of moles of zinc chloride produced by Zn are less so it will limiting reactant.
Mass of zinc chloride:
Mass = number of moles × molar mass
Mass = 0.08 mol × 136.3 g/mol
Mass = 11 g
