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galben [10]
4 years ago
6

Which method of testing substances is a sure way to identify a chemical reaction?

Physics
2 answers:
Nataly [62]4 years ago
8 0
Change in color, increase of temperature, formulation in bubbles
NISA [10]4 years ago
3 0

Answer:

It C. change in density (I WAS INCORRECT ON PLATO TEST IT IS NOT C)

Explanation:

"To definitively determine that a chemical reaction has taken place, it is necessary to carefully test the properties of reactants and products. Each substance has a unique set of properties. One of them is density. We can determine whether two substances are the same or different by calculating and comparing their densities. No two substances in their purest form have the same density." this is from my plato science notes

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Calculate the energy, wavelength, and frequency of the emitted photon when an electron moves from an energy level of -3.40 eV to
jasenka [17]

Answer:

(a) The energy of the photon is 1.632 x 10^{-8} J.

(b) The wavelength of the photon is 1.2 x 10^{-17} m.

(c) The frequency of the photon is 2.47 x 10^{25} Hz.

Explanation:

Let;

E_{1} = -13.60 ev

E_{2} = -3.40 ev

(a) Energy of the emitted photon can be determined as;

E_{2} - E_{1} = -3.40 - (-13.60)

           = -3.40 + 13.60

           = 10.20 eV

           = 10.20(1.6 x 10^{-9})

E_{2} - E_{1} = 1.632 x 10^{-8} Joules

The energy of the emitted photon is 10.20 eV (or 1.632 x 10^{-8} Joules).

(b) The wavelength, λ, can be determined as;

E = (hc)/ λ

where: E is the energy of the photon, h is the Planck's constant (6.6 x 10^{-34} Js), c is the speed of light (3 x 10^{8} m/s) and λ is the wavelength.

10.20(1.6 x 10^{-9}) = (6.6 x 10^{-34} * 3 x 10^{8})/ λ

λ = \frac{1.98*10^{-25} }{1.632*10^{-8} }

  = 1.213 x 10^{-17}

Wavelength of the photon is 1.2 x 10^{-17} m.

(c) The frequency can be determined by;

E = hf

where f is the frequency of the photon.

1.632 x 10^{-8}  = 6.6 x 10^{-34} x f

f = \frac{1.632*10^{-8} }{6.6*10^{-34} }

 = 2.47 x 10^{25} Hz

Frequency of the emitted photon is 2.47 x 10^{25} Hz.

6 0
3 years ago
In a computer simulation, Juan moves a magnet (Magnet 1) closer to another magnet (Magnet 2) that cannot move. Which statement a
tekilochka [14]

Answer:

C

Explanation:

The potential energy decreases because Magnet 1 moves against the magnetic force. If it was increased it would be kinetic

8 0
3 years ago
Read 2 more answers
A student dips a strip of metal into a liquid. Which is evidence that only a physical change has occurred?
sattari [20]

Answer:

PLS add the picture too.....

3 0
3 years ago
Question 6 (1 point)
jarptica [38.1K]

Explanation:

decrease,then increase

8 0
3 years ago
The colors of the stars in the sky range from red to blue. Assuming that the color indicates the frequency at which the star rad
Crazy boy [7]

Answer:

a) 4458K b) 5048K, c) 6166K, d) 5573K

Explanation:

The temperature of the stars and many very hot objects can be estimated using the Wien displacement law

    \lambda_{max} T = 2,898 10⁻³ [m K]

    T = 2,898 10⁻³ / \lambda_{max}

a) indicate that the wavelength is

    Lam = 650 nm (1 m / 109 nm) = 650 10⁻⁹ m

    Lam = 6.50 10⁻⁷ m

    T = 2,898 10⁻³ / 6.50 10⁻⁷

    T = 4,458 10³ K

    T = 4458K

b) lam = 570 nm = 5.70 10⁻⁷ m

    T = 2,898 10⁻³ / 5.70 10⁻⁷

    T = 5084K

c) lam = 470 nm = 4.70 10⁻⁷ m

    T = 2,898 10⁻³ / 4.7 10⁻⁷

    T = 6166K

d) lam = 520 nm = 5.20 10⁻⁷ m

    T = 2,898 10⁻³ / 5.20 10⁻⁷

    T = 5573K

5 0
4 years ago
Read 2 more answers
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