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2 years ago

.The 1" row of the periodic table has which two elements?

1 answer:

5 0

On the periodic table, hydrogen and helium are the only two elements in the first row, or period, which reflects that they only have electrons in their first shell. Hydrogen and helium are the only two elements that have electrons exclusively in the 1 s 1s 1s orbital in their neutral, non-charged, state.

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Calculate the wavelength, in nanometers, of the spectral line produced when an electron in a hydrogen atom undergoes the transit

Lapatulllka [165]

<u>Answer:</u> The wavelength of spectral line is 656 nm

<u>Explanation:</u>

To calculate the wavelength of light, we use Rydberg's Equation:

$\frac{1}{\lambda}=R_H\left(\frac{1}{n_f^2}-\frac{1}{n_i^2} \right )$

Where,

$\lambda$ = Wavelength of radiation

$R_H$ = Rydberg's Constant = $1.097\times 10^7m^{-1}$

$n_f$ = Final energy level = 2

$n_i$ = Initial energy level = 3

Putting the values in above equation, we get:

$\frac{1}{\lambda }=1.097\times 10^7m^{-1}\left(\frac{1}{2^2}-\frac{1}{3^2} \right )\\\\\lambda =\frac{1}{1.524\times 10^6m^{-1}}=6.56\times 10^{-7}m$

Converting this into nanometers, we use the conversion factor:

$1m=10^9nm$

So, $6.56\times 10^{-7}m\times (\frac{10^9nm}{1m})=656nm$

Hence, the wavelength of spectral line is 656 nm

6 0

3 years ago

It is becoming less expensive to screen blood samples for DNA. Certain diseases have a genetic basis. What is a possible ethical

sveta [45]

Answer:

The answer you would be looking for is option A because all of the other options are either false, or beneficial to us, and i took the test. Thanks

Explanation:

8 0

3 years ago

Read 2 more answers

An isotope of cesium has 55 protons and 78 neutrons. What is the mass number of this isotope?

mixer [17]

The only stable caesium isotope is 133Cs, with 78 neutrons.

Hope this answers your Q

4 0

3 years ago

What is the final concentration (M) of a solution prepared by diluting 50.0 mL of a solution to a volume of

docker41 [41]

0.600
D) 0.600 is the final concentration of the solution of KCl.
V1 = 50.0 mL.

6 0

2 years ago

What is the energy of a photon having a wavelength of 2.60 ✕ 10-8 m?<br> J

zvonat [6]

The energy of a photon : 7.645 x 10⁻³⁴ J

<h3>Further explanation </h3>

Radiation energy is absorbed by photons

The energy in one photon can be formulated as

$\large{\boxed{\bold{E\:=\:h\:.\:f}}}$

Where

h = Planck's constant (6,626.10⁻³⁴ Js)

f = Frequency of electromagnetic waves

f = c / λ , Hz

c = speed of light

= 3.10⁸ m/s

λ = wavelength ,m

wavelength λ of 2.60 ✕ 10⁻⁸ m

The energy :

$\tt E=h.\dfrac{c}{\lambda}\\\\E=6.626.10^{-34}\times \dfrac{3\times 10^8}{2.6\times 10^{-8}}\\\\E=7.645\times 10^{-34}~J$

3 0

3 years ago