Do You have a pictures of the Cylinders? it would help alot
Answer:
A. Helium
Explanation:
In chemistry, a noble gas refers to a group of elements placed in group 18, which is located in the last column from left to right in the periodic table. Additionally, these elements are defined by their low reactivity, also as gases, they do not have color or odor. Helium is part of this group that contains other 5 elements because Helium characteristics are similar to other noble gases, indeed this is the first noble gas in the periodic table. Additionally, helium is an abundant element found in all the universe especially in stars. Thus, the element that is a noble gas is Helium.
Answer: How to calculate the mass percent by using these instructions
1.The molar mass is the mass of a given chemical element or chemical compound (g) divided by the amount of substance (mol).
2.The molar mass of a compound can be calculated by adding the standard atomic masses (in g/mol) of the constituent atoms.
Explanation:
Answer:
Percentage of a sample remains after 60.0 min is 13.03%.
Explanation:
- It is known that the decay of isotopes of C-11 obeys first order kinetics.
- Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
- Half-life time (t1/2) in first order reaction = 0.693/k, where k is the rate constant.
∴ k = 0.693/(t1/2) = 0.693/(20.4 min) = 0.03397 min⁻¹.
- The integrated law for first order reaction is:
<em>kt = ln[A₀]/[A],</em>
where, k is the rate constant (k = 0.03397 min⁻¹).
t is the time of the reaction (t = 60.0 min).
[A₀] is the initial concentration of C-11 ([A₀] = 100.0 %).
[A] is the remaining concentration of C-11 ([A] = ???%).
<em>∵ kt = ln[A₀]/[A]</em>
∴ (0.03397 min⁻¹)(60.0 min) = ln(100%)/[A]
∴ 2.038 = ln(100%)/[A]
∴ 7.677 = (100%)/[A]
<em>∴ [A] </em>= (100%)/(7.677) = <em>13.03%.</em>
<em>So, percentage of a sample remains after 60.0 min is 13.03%.</em>