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vovangra [49]
3 years ago
10

If the atomic number of an atom is 4 and the mass number is 9, then how many electrons does it have

Physics
1 answer:
miskamm [114]3 years ago
5 0
The atomic number of an atom says how many protons it has. This number cant change, since the atomic number is what gives elements their identities (in the periodic table, at least).
The mass number, on the other hand, says how many protons AND neutrons the atom has (so, the sum of P+ and N0). So, electrons have nothing to do with this number.
Atoms are neutrally charged, which means there has to be an equal number of positive and negative particles. The negative particles of an atom are its electrons, and since our atom has 4 protons, it must also have 4 electrons.
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bagirrra123 [75]

Answer: C

Frictional force

Explanation:

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For a car travelling in a curved path, the frictional force between the tyres and the road surface will provide the centripetal force.

Since the road is banked, and the cross section of the banked road is constructed like a ramp. The car drives transversely to the slope of the ramp, so that the wheels of one side of the car are lower than the wheels on the other side of the car, for cornering the banked road, the car will not rely only on the frictional force.

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3 years ago
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Please help me with this question :
aalyn [17]

Answer:

  • 514.27 ( wavelength )

the color is green

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Explanation:

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refraction n = 1.33

wall thickness (t) = 290 nm

2nt = (2m +1 ) ∝/2 -----equation 1

note when m = 0

therefore ∝ =  4nt/ 1 = 4 * 1.33 * 290 = 1542.8nm we will discard this

when m = 1

equation 1 becomes

∝ = 4nt/3 =( 4 * 1.33 * 290) /  3 = 1542.8 / 3 = 514.27 ( wavelength )

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B) the wavelength when the wall thickness is 340 nm

∝ = 4nt / 2m +1

where m = 1

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the observation is that there is a change of visible color

7 0
3 years ago
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liberstina [14]
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