Answer:
0.0468 g.
Explanation:
- The decay of radioactive elements obeys first-order kinetics.
- For a first-order reaction: k = ln2/(t1/2) = 0.693/(t1/2).
Where, k is the rate constant of the reaction.
t1/2 is the half-life time of the reaction (t1/2 = 1620 years).
∴ k = ln2/(t1/2) = 0.693/(1620 years) = 4.28 x 10⁻⁴ year⁻¹.
- For first-order reaction: <em>kt = lna/(a-x).</em>
where, k is the rate constant of the reaction (k = 4.28 x 10⁻⁴ year⁻¹).
t is the time of the reaction (t = t1/2 x 8 = 1620 years x 8 = 12960 year).
a is the initial concentration (a = 12.0 g).
(a-x) is the remaining concentration.
∴ kt = lna/(a-x)
(4.28 x 10⁻⁴ year⁻¹)(12960 year) = ln(12)/(a-x).
5.54688 = ln(12)/(a-x).
Taking e for the both sides:
256.34 = (12)/(a-x).
<em>∴ (a-x) = 12/256.34 = 0.0468 g.</em>
Gravity is a force that acts between the Earth's mass and the mass of other objects that surround it. ... Astronauts merely feel weightless because there is no external contact force pushing or pulling upon their body. They are in a state of free fall.
Johnny has 69420 sperm cells, he busts 420 sperm cells. How much sperm is left??
Answer:
The Sun and the planets were born from a cloud of gas and dust called the solar nebula 4.6 billion years ago. The collapse of the solar nebula was most likely triggered by a shock wave from a nearby supernova explosion. The Sun formed in the center, with the planets surrounding it in a thin disk.
Explanation:
<span>Isotopes are atoms of the same element with the same
number of protons and same number of electrons but with <span>different number of neutrons. They differ in the number of neutrons that
is why they also differ in mass numbers. Since they have the same number of
protons, they have the same atomic number.
For instance, when the nucleus of the isotope with a 68.926 amu, there are 30
protons and 39 neutrons in the nucleus. The best example for this is Zn (zinc-69
isotope) and Ga (gallium-69 isotope) which has 68.926 amu and 68.925 amu
respectively. </span></span>
