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liq [111]
3 years ago
6

List the 5 signs of a CHEMICAL REACTION

Chemistry
1 answer:
SVETLANKA909090 [29]3 years ago
6 0
Color change, formation of a precipitation, formation of a gas, odor change, temperature change
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In compliance with conservation of energy, Einstein explained that in the photoelectric effect, the energy of a photon (hv) abso
3241004551 [841]

Answer:

 a) 1.866 × 10 ⁻¹⁹ J      b)   3.685 × 10⁻¹⁹ J

Explanation:

the constants involved are

h ( Planck constant) = 6.626 × 10⁻³⁴ m² kg/s

Me of electron = 9.109 × 10 ⁻³¹ kg

speed of light = 3.0 × 10 ⁸ m/s

a) the Ek ( kinetic energy of the dislodged electron) = 0.5 mu²

Ek = 0.5 × 9.109 × 10⁻³¹ × ( 6.40 × 10⁵ )² = 1.866 × 10 ⁻¹⁹ J

b) Φ ( minimum energy needed to dislodge the electron ) can be calculated by this formula

hv =   Φ + Ek

where Ek = 1.866 × 10 ⁻¹⁹ J

v ( threshold frequency ) = c / λ where c is the speed of light and λ is the wavelength of light = 358.1 nm = 3.581 × 10⁻⁷ m

v = ( 3.0 × 10 ⁸ m/s ) / (3.581 × 10⁻⁷ m ) = 8.378 × 10¹⁴ s⁻¹

hv = 6.626 × 10⁻³⁴ m² kg/s ×  8.378 × 10¹⁴ s⁻¹ = 5.551 × 10⁻¹⁹ J

5.551 × 10⁻¹⁹ J = 1.866 × 10 ⁻¹⁹ J + Φ

Φ = 5.551 × 10⁻¹⁹ J - 1.866 × 10 ⁻¹⁹ J = 3.685 × 10⁻¹⁹ J

7 0
3 years ago
What is the atomic number of an atom that has 20 protons and 20 neutrons
vladimir2022 [97]

Answer:

20

Explanation:

Hi there!

We need to find the atomic number of an atom that has 20 protons and 20 neutrons

the atomic number of an atom is equivalent to the amount of protons an atom has, as the number of protons determines what element an atom is.

Since the atom has 20 protons, the atomic number of the said atom is <u>20</u>

Hope this helps!  

5 0
3 years ago
Which atmosphere layer is represented by F what are its characteristics
inysia [295]

That wouod be the ionosphere!

6 0
3 years ago
Which of the following is true of carbon?
pashok25 [27]
I’m pretty sure it’s A or C
8 0
3 years ago
Read 2 more answers
Match the characteristics and elements to their group.
Luba_88 [7]

Answer:

Kr is a Noble Gas. Na is an alkali metal. F is halogen.

Group 17 is halogens. Inert is Noble Gases. Odourless and colourless is Noble Gases. Alkali metals do not occur freely in nature. Alkali metals are malleable

Explanation:

8 0
3 years ago
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