The unit 'mW' means milliwatts. It is a unit of work. There are 1,000 milliwatts in a 1 Watt of work. In 4 hours, there are 14,400 seconds.
Work= Energy/time
17 mW * 1 W/1000 mW = Energy/(14,400 seconds)
Solving for energy,
Energy = 244.8 J
Energy/photon = 244.8 J/(6.04×10²⁰) = 4.053×10⁻¹⁹ J/photon
Using the Planck's equation:
E = hc/λ
where h = 6.626×10⁻³⁴ m²·kg/s, c = 3,00,000,000 m/s and λ is the wavelength
4.053×10⁻¹⁹ J/photon = (6.626×10⁻³⁴ m²·kg/s)(3,00,000,000 m/s)/λ
λ = 4.9×10⁻⁷ m or 49 micrometers
The average atomic mass of element X is 14.007 u.
The average atomic mass of X is the <em>weighted average</em> of the atomic masses of its isotopes.
We multiply the atomic mass of each isotope by a number representing its <em>relative importance</em> (i.e., its % abundance).
Thus,
0.996 36 × 14.003 u =13.952 03 u
0.003 64 × 15.000 u = <u>0.054 60 u</u>
__________TOTAL = 14.007 u
Answer:

Explanation:
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In this case, given the T-V variation, we understand it is possible to apply the Charles' law as shown below:

Thus, since we are interested in the initial temperature, we can solve for T1, plug in the volumes and use T2 in kelvins:

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The option in “the mass of 1me of carbon equals the mass of 1 mole of boron atoms” is false since
Mass=molesx molar mass
And the molar masses of these two elements are different so their masses aren’t equal