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1 year ago

Please help me, i don’t understand :(

Chemistry

2 answers:

soldier1979 [14.2K]1 year ago

4 0

Answer:

weathering

Explanation:

different states of the u.s and what climate it is in every state.

Citrus2011 [14]1 year ago

4 0

The map displays weather, and based on the map showed, Texas stormy on mostly the north side as to sunny on south

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Consider a transition of the electron in the hydrogen atom from n=3 to n=7.

kow [346]

Answer:

For a: The wavelength of light is $1.005\times 10^{-6}m$

For b: The light is getting absorbed

Explanation:

For a:

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

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

Where,

$\lambda$ = Wavelength of radiation

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

$n_f$ = Higher energy level = 7

$n_i$ = Lower energy level = 3

Putting the values in above equation, we get:

$\frac{1}{\lambda }=1.097\times 10^7m^{-1}\left(\frac{1}{3^2}-\frac{1}{7^2} \right )\\\\\lambda =1.005\times 10^{-6}m$

Hence, the wavelength of light is $1.005\times 10^{-6}m$

For b:

There are two ways in which electrons can transition between energy levels:

Absorption spectra: This type of spectra is seen when an electron jumps from lower energy level to higher energy level. In this process, energy is absorbed.
Emission spectra: This type of spectra is seen when an electron jumps from higher energy level to lower energy level. In this process, energy is released in the form of photons.

As, the electron jumps from lower energy level to higher energy level. The wavelength is getting absorbed.

6 0

2 years ago

Tim wants to store 0.122 moles of helium gas at 203 kPa and 401 K. Which is the volume of the helium gas needed for storage?

algol13

The volume of Helium gas needed for storage is 2.00 L (answer C)

calculation

The volume of Helium is calculated using ideal gas equation

That is Pv =nRT

where;

P( pressure) = 203 KPa

V(volume)=?

n(number of moles) = 0.122 moles

R(gas constant) = 8.314 L.Kpa/mol.K

T(temperature)= 401 K

make V the subject of the formula by diving both side by P

V=nRT/p

V={[0.122 moles x 8.314 L. KPa/mol.K x 401 K] / 203 KPa} = 2.00 L

3 0

2 years ago

As with any drug, aspirin (acetylsalicylic acid) must remain in the bloodstream long enough to be effective. Assume that the rem

Olenka [21]

Answer:

180 mg

Explanation:

For a first-order reaction, we can calculate the amount of aspirine (A) at a certain time (t) using the following expression.

$A=A_{0}.e^{-k.t}$

where,

k: rate constant

A₀: initial amount

If we know the half-life ( $t_{1/2}$ ) we can calculate the rate constant.

$k=\frac{ln2}{t_{1/2}} =\frac{ln2}{3h} =0.2h^{-1}$

When t = 4 h and A₀ = 400 mg, A is:

$A=400mg.e^{-0.2h^{-1}\times 4h} =180mg$

4 0

2 years ago

The use of crucible

Norma-Jean [14]

a ceramic or metal container in which metals or other substances may be melted or subjected to very high temperatures.

"the crucible tipped and the mold filled with liquid metal"

a situation of severe trial, or in which different elements interact, leading to the creation of something new.

"their relationship was forged in the crucible of war"

3 0

2 years ago

Complete each of the definitions with the appropriate phrase. Precision means that measurements are close to Accuracy means that

sergiy2304 [10]

Answer: Precision means that measurements are close to each other . Accuracy means that measurements are close to accepted value

Explanation:

Precision refers to the closeness of two or more measurements to each other.

For Example: If we weigh a given substance five times and you get 5.0 kg each time. Then the measurement is very precise.

Accuracy refers to the closeness of a measured value to a standard or known value.

For Example: If the mass of a substance is 5.0 kg and one person weighed 4.9 kg and another person weighed 3.9 kg. Then, the weight measured by first person is more accurate.

Thus Precision means that measurements are close to each other . Accuracy means that measurements are close to accepted value.

5 0

2 years ago