Explanation:
Use half life equation:
A = A₀ (½)^(t / T)
where A is the final amount,
A₀ is the initial amount,
t is time,
and T is half life.
0.375 = 3 (½)^(1 / T)
0.125 = (½)^(1 / T)
(½)^3 = (½)^(1 / T)
3 = 1 / T
T = 1/3 hours
T = 20 minutes
Answer:
Explanation:
The formula for hydrogen atomic spectrum is as follows
energy of photon due to transition from higher orbit n₂ to n₁

For layman series n₁ = 1 and n₂ = 2 , 3 , 4 , ... etc
energy of first line

10.2 eV
wavelength of photon = 12375 / 10.2 = 1213.2 A
energy of 2 nd line

= 12.08 eV
wavelength of photon = 12375 / 12.08 = 1024.4 A
energy of third line

12.75 e V
wavelength of photon = 12375 / 12.75 = 970.6 A
energy of fourth line

= 13.056 eV
wavelength of photon = 12375 / 13.05 = 948.3 A
energy of fifth line

13.22 eV
wavelength of photon = 12375 / 13.22 = 936.1 A
Upwelling currents in the molten material beneath the crust.
The rocks that make up the crust are light, compared with the metal-rich material beneath. The crust floats on top like an iceberg. Slow-moving currents underneath propel the continents around the surface