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Yuliya22 [10]
2 years ago
8

Which of the following is a Nobel gas? Ba2+ OA OB. Ci Kr Ос. Ca D.

Physics
1 answer:
stepan [7]2 years ago
5 0

Answer:

Kr

Explanation:

the element that is in group 18 is noble gasses. the elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).

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By calculating its wavelength (in nm), show that the second line in the Lyman series is UV radiation.
Rashid [163]

Answer:

 λ = 102.78  nm

This radiation is in the UV range,

Explanation:

Bohr's atomic model for the hydrogen atom states that the energy is

           E = - 13.606 / n²

where 13.606 eV   is the ground state energy and n is an integer

an atom transition is the jump of an electron from an initial state to a final state of lesser emergy

            ΔE = 13.606 (1 / n_{f}^{2} - 1 / n_{i}^{2})

the so-called Lyman series occurs when the final state nf = 1, so the second line occurs when ni = 3, let's calculate the energy of the emitted photon

            DE = 13.606 (1/1 - 1/3²)

            DE = 12.094 eV

let's reduce the energy to the SI system

            DE = 12.094 eV (1.6 10⁻¹⁹ J / 1 ev) = 10.35 10⁻¹⁹ J

let's find the wavelength is this energy, let's use Planck's equation to find the frequency

            E = h f

             f = E / h

            f = 19.35 10⁻¹⁹ / 6.63 10⁻³⁴

            f = 2.9186 10¹⁵ Hz

now we can look up the wavelength

           c = λ f

           λ = c / f

           λ = 3 10⁸ / 2.9186 10¹⁵

           λ = 1.0278  10⁻⁷ m

let's reduce to nm

            λ = 102.78  nm

This radiation is in the UV range, which occurs for wavelengths less than 400 nm.

5 0
3 years ago
Determine the mechanical energy of this object a 1-kg ball rolls on the ground at <br> m/s
dedylja [7]
Mechanical energy = potential energy + kinetic energy
The ball is on the ground so it has no potential energy. that's all i know.
8 0
3 years ago
Which descriptions best fit the labels? X: kinetic energy Y: potential energy X: potential energy Y: kinetic energy X: mechanica
GalinKa [24]

its the 3rd option!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

4 0
3 years ago
Read 2 more answers
Can we travel back in time?​
KATRIN_1 [288]

Answer:

I do not believe so.

Explanation:

We have not advanced that far yet in our society.

3 0
3 years ago
Which of the following methods of soil conservation uses the roots of plants as anchors in the soil? (2 points) Adding fertilize
julsineya [31]
I believe the correct answer is the second option. Planting of trees on sloped surfaces is a method of conservation that utilizes the roots of plants. Planting trees on such areas would prevent hazards and maintain the soil formation future since the roots would hold the soil together preventing or minimizing any soil erosion.
8 0
4 years ago
Read 2 more answers
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