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2 years ago

11

An electron in the ground state absorbs a single photon of light and then relaxes back to the ground state by emitting an infrar

ed photon (1200 nm) followed by an orange photon (600 nm). What is the wavelength of the absorbed photon?
A. 400 nm
B. 600 nm
C. 1800 nm

1 answer:

vladimir2022 [97]2 years ago

7 0

B. 600 nm would be the wavelength

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If the same amount of heat is added to 25.0 g of each of the metals, which are all at the same initial temperature, which metal

AVprozaik [17]

Answer:

The bismuth sample.

Explanation:

The specific heat $c$ of a substance (might not be a metal) is the amount of heat required for heating a unit mass of this substance by unit temperature (e.g., $\rm 1\; ^{\circ}C$ .) The formula for specific heat is:

$\displaystyle c = \frac{Q}{m \cdot \Delta T}$ ,

where

$Q$ is the amount of heat supplied.
$m$ is the mass of the sample.
$\Delta T$ is the increase in temperature.

In this question, the value of $Q$ (amount of heat supplied to the metal) and $m$ (mass of the metal sample) are the same for all four metals. To find $\Delta T$ (change in temperature,) rearrange the equation:

$\displaystyle c \cdot \Delta T = \frac{Q}{m}$ ,

$\displaystyle \Delta T = \frac{Q}{c \cdot m}$ .

In other words, the change in temperature of the sample, $\Delta T$ can be expressed as a fraction. Additionally, the specific heat of sample, $c$ , is in the denominator of that fraction. Hence, the value of the fraction would be the largest for sample with the smallest specific heat.

Make sure that all the specific heat values are in the same unit. Find the one with the smallest specific heat: bismuth ( $\rm 0.123 \; J \cdot g\cdot \,^{\circ}C^{-1}$ .) That sample would have the greatest increase in temperature. Since all six samples started at the same temperature, the bismuth sample would also have the highest final temperature.

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3 years ago

Using the VSEPR theory , what would the representation mean A central atom with 2 connected atoms atom with I lone pair of Jone

VLD [36.1K]

Answer:

The molecule has a bent geometry

Explanation:

Let us look again at the principles of VSEPR theory. The shape of a molecule depends on the number of electron pairs that surround the valence shell of the central atom in the molecule.

Lone pairs distort the molecular geometry away from what is expected on the basis of VSEPR theory.

The molecule described in the question has the form AEX2. Two substituents and one lone pair form three electron domains around the central atom. The expected geometry is trigonal planar but the observed molecular geometry is bent because of the lone pairs present.

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3 years ago

Decreasing the temperature of the reaction 3H2 + N2<----->2NH3. In this reaction, the product absorbs heat. WHICH WAY WILL

AURORKA [14]

$3H_{2}$ + $N_{2}$ ⇔ $2NH_{3}$

Decreasing the temperature of the reaction,the reaction shifts forward.

The explanation is given below.

Explanation:

If the temperature of the reaction mixture is increased,then the equilibrium will shift to decrease the temperature.

If the temperature of the reaction mixture is decreased,then the equilibrium will shift to increase the temperature.

During the formation of the ammonia,it gives off heat.So it is an exothermic reaction.

$3H_{2}$ + $N_{2}$ ⇔ $2NH_{3}$

A decrease in the temperature favors the reaction that is exothermic (the forward reaction)because it produces energy.Therefore,if the temperature is decreased,the yield of the ammonia increases.

<em>Therefore if the temperature is increased,the reaction shifts forward and the yield of the ammonia increases and it is an exothermic reaction.</em>

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3 years ago

You have a mass of 54 kg and are sitting on a stool. The normal force the stool applies on you is ...

Karo-lina-s [1.5K]

Answer:

529.2 N

Explanation:

As we have studied the first law of motion, which states that every action has some reaction, equal in magnitude but having an opposite direction.

The force that is acting on the student will be due to gravitational force, that is equal to his weight.

F=mg: 54kg x 9.8m/s^2 =529.2 N

So the weight of student is exerting downwards towards the stool and land. The stool will also exert a force on the student that will be equal in magnitude but opposite in direction, then it will be 529.2 N.

This is because the student is sitting in a constant state and all the weight is exerted on the stool.

Note: This answer is very generic supposing that all the weight of the student is on stool. But, if we suppose that student's legs are on floor so it means the force of gravity acting on the stool has become less because student's mass on stool is less. So the answer would be a force somehow less than 529.2 N. However, since the question asked normal force, it would be weight of student in general terms.

Hope it helps!

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2 years ago

Steam initially at 0.3 MPa, 2500 C is cooled at constant volume. (a) At what temperature will steam become saturated vapour? [12

AlladinOne [14]

Answer:

a. 123.9°C

b.

c.

Explanation:

Hello, I'm attaching a picture with the numerical development of this exercise.

a. Since the steam is overheated vapour, the specific volume is gotten from the corresponding table. Then, as it became a saturated vapour, we look for the interval in which the same volume of state 1 is, then we interpolate and get the temperature.

b. Now, at 80°C, since it is about a rigid tank (constant volume for every thermodynamic process), the specific volume of the mixture is 0.79645 m^3/kg as well, so the specific volume for the liquid and the vapour are taken into account to get the quality of 0.234.

c. Now,since this is an isocoric process, the heat transfer per kg of steam is computed as the difference in the internal energy, considering the initial condition (showed in a. part) and the final one computed here.

** The thermodynamic data were obtained from Cengel's thermodynamics book 7th edition.

Best regards.

5 0

3 years ago