The nuclide as-76 has a half-life of 26.0 hours. if a sample of as-76 weighs 344 g, what mass of as-76 remains after 538 minutes? a) 67.8 g b) 271 g c) 144 g d) 437 g e) 251 g 26.

B) 271 g.

Explanation:

k = ln(2)/(t1/2) = 0.693/(t1/2).

Where, k is the rate constant of the reaction.

t1/2 is the half-life of the reaction.

∴ k =0.693/(t1/2) = 0.693/(26.0 hours) = 0.02665 hour⁻¹.

kt = ln([A₀]/[A]),

where, k is the rate constant of the reaction (k = 0.02665 hour⁻¹).

t is the time of the reaction (t = 538 min = 8.97 hour).

[A₀] is the initial concentration of (As-76) ([A₀] = 344 g).

[A] is the remaining concentration of (As-76) ([A] = ??? g).

∴ (0.02665 hour⁻¹)(8.97 hour) = ln((344 g)/[A])

∴ 0.239 = ln((344 g)/[A]).

∴ 1.27 = ((344 g)/[A]).

∴ [A] = (344 g)/(1.27) = 270.88 g ≅ 271 g.

2h2o2--> 2h2o + o2

this reaction is of the spontaneous decomposition of hydrogen peroxide down into water and oxygen.

add 2 molecules of hydrogen peroxide and 2 molecules of water. since oxygen is naturally diatomic, the total number of atoms of each element is now the same on both sides of the equation so it is balanced.

this may not be entirely correct but let me know.

the earth would become to overheated and everything alive on it will eventually die from overheating. plants will eventually die as well, water will evaporate, and it will be nothing but a hot planet without anything living on it.