Answer:
7.941
Explanation:
You can look at a picture of the periodic table.To calculate the atomic mass of a single atom of an element, add up the mass of protons and neutrons. Example: Find the atomic mass of an isotope of carbon that has 7 neutrons. You can see from the periodic table that carbon has an atomic number of 6, which is its number of protons.
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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>
When NAD becomes NADH, it is being reduced and gaining chemical energy.
Nicotinamide adenine dinucleotide (NAD), a coenzyme, can exist in two forms, NAD⁺ (oxidized) and NADH (reduced form).
Electrons and protons released in catabolism reactions are attached to NAD⁺. The conversion of NAD⁺ to NADH is important reaction for production of ATP during the cellular respiration.
Reduction is lowering oxidation number because element, ion or compound gain electrons.
Chemical equation for reaction of reduction of NAD⁺ (see picture below):
NAD⁺ + 2e⁻ + H⁺ → NADH
Nicotinamide adenine dinucleotide (NAD) is made of two nucleosides joined by pyrophosphate.
More about reduction :brainly.com/question/25334331
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