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vodka [1.7K]
3 years ago
6

1. Which statement about subatomic particles is not true?

Physics
1 answer:
igomit [66]3 years ago
8 0

1. Protons and neutrons have the same charge.

Protons have positive charge, equal to e=+1.6\cdot 10^{-19} C, while neutrons have zero charge.

2. mass number

The mass number of an atom is equal to the sum of protons and neutrons inside its nucleus.

3. Atoms are made up of smaller particles.

According to Dalton's theory, atoms are the smallest particles that make matter, and they are indivisible and indestructible, so they are NOT made up of smaller particles.

4. a solid sphere

In Dalton's theory, atoms are not made of smaller particles, so we can think them as solid spheres.

5. J. J. Thomson

In his experiment with cathode ray tubes, JJ Thomson demonstrated the existance of the electrons, which are negatively charged particles inside the atom. In his model of the atom (plum-pudding model), Thomson thought the atom consists of a uniform positive charge and the electrons are located inside this positive charge.

6. An electron has the same amount of energy in all orbitals.

In fact, each orbital corresponds to a different energy level: the farther the orbital from the nucleus, the higher the energy of the electrons contained in that orbital.

7. A hydrogen atom in heavy water has an extra neutron.

Heavy water is a type of water that contains deuterium, which is an isotope of the hydrogen consisting of one proton and one neutron (so, one extra neutron).

8. The glowing beam was always deflected by charged plates

In his cathode's ray tube experiment, Thomson shows that the beam of unknown particles (= the electrons) were deflected by charge plates, so the particles had to be also electrically charged.

9. electrons move to a lower energy level

When electrons move from a higher energy level to a lower energy, they emit a photon (light) of energy equal to the difference in energy between the two energy levels.

10. orbital

In quantum mechanics, electrons in the atom are not precisely located, since we cannot determine their exact position and velocity at the same time. Therefore, we can only describe regions of space where the electrons have a certain probability to be found, and these regions of space are called orbitals.

11. 14

According to Dalton's theory, the proportions of the reactants must be respected in order to form the same compound. Therefore, we can write:

2 g: 4 g = X : 28 g\\X=\frac{2 g \cdot 28 g}{4 g}=14 g

12. negative charge, found outside the nucleus

Electrons are particles with negative charge of magnitude e=-1.6\cdot 10^{-19}C that orbit around the nucleus. The nucleus, instead, consists of protons (positively charged, with charge opposite to the electron) and neutrons (neutrally charged).

13. move from higher to lower energy levels

When electrons move from a higher energy level to a lower energy inside a neon atom, they emit a photon (which is light) whose energy is equal to the difference in energy between the two energy levels.

14. atomic number from its mass number

In fact:

- the atomic number of an atom (Z) is equal to the number of protons inside the nucleus

- the mass number of an atom (A) is equal to the sum of protons+neutrons inside the nucleus

Therefore, we can find the number of neutrons in the nucleus by calculating the difference between A and Z:

Number of neutrons = A - Z

15. None of them

None of these examples is a good analogy to describe the location of an electron in an atomic orbital: in fact, the position of an electron in an orbital cannot be precisely described, we can only describe the probability to find the electron in a certain position, and none of these example is an analogy of this model.

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He can throw it away from himself.

Explanation:

Newtons Third Law says that everything has an equal, yet opposite reaction on other objects.

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In a Young's double-slit experiment, light of wavelength 500 nm illuminates two slits which are separated by 1 mm. The separatio
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Answer:

b. 0.25cm

Explanation:

You can solve this question by using the formula for the position of the fringes:

y=\frac{m\lambda D}{d}

m: order of the fringes

lambda: wavelength 500nm

D: distance to the screen 5 m

d: separation of the slits 1mm=1*10^{-3}m

With the formula you can calculate the separation of two adjacent slits:

\Delta y=\frac{(m+1)(\lambda D)}{d}-\frac{m\lambda D }{d}=\frac{\lambda D}{d}\\\\\Delta y=\frac{(500*10^{-9}nm)(5m)}{1*10^{-3}m}=2.5*10^{-3}m=0.25cm

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3 years ago
An object falls freely for 25 seconds, what is the velocity after the 25 seconds ?
Andrei [34K]
The acceleration of gravity on Earth is 9.8 m/s² downward.
This means that gravity adds 9.8 m/s downward to the speed
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So after 25 sec, it's falling (25 x 9.8m/s) = 245 m/s faster than
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If it dropped from rest (no speed), then its velocity
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What is the exact meaning of croos section and cross sectional area of a conductor?
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The cross-sectional area of the wire is the area of that little circle. 
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Red light of wavelength 633 nmnm from a helium-neon laser passes through a slit 0.400 mmmm wide. The diffraction pattern is obse
erik [133]

Answer:

a

 y_1 = 0.004589 \ m

b

 y_2 =0.009179 \  m

Explanation:

From the question we are told that

   The wavelength of the red light is  \lambda _r  = 633 \ nm  =  633 *10^{-9} \  m

    The width of the slit is  d = 0.40 mm = 0.40 *10^{-3} \  m

    The distance of the screen from the point of diffraction is D  =  2.9 \  m

Generally the width of the central bright fringe is mathematically represented as

       y_1 = \frac{\lambda * D}{d}

=>    y_1 = \frac{633 *10^{-9} * 2.90 }{0.40 *10^{-3}}

=>    y_1 = 0.004589 \ m

Generally the width of the first bright fringe on either side of the central one is mathematically represented as

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=>   y_2 = 2 * 0.004589

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