Answer:
0.42
Explanation:
"Which of the following statements about electrons is not true?
1 answer:
Answer:
B) Within an atom, an electron can have only particular energies.
Explanation:
As we know that electrons have energy but apart from electrons we know that protons and neutrons inside the nucleus of atom will also have energy in them.
rest all the statements are true as we have
A) Electrons orbit the nucleus rather like planets orbiting the Sun.
TRUE, because electrons can move in stationary orbit around the nucleus
C) Electrons can jump between energy levels in an atom only if they receive or give up an amount of energy equal to the difference in energy between the energy levels.
Difference amount of energy is lost or absorbed by the electron in form of photons
D) An electron has a negative electrical charge.
Charge of an electron is given as
E) Electrons have very little mass compared to protons or neutrons
Mass of an electron is given as
mass of proton or neutron
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Answer:
The speed of the electron is 1.371 x 10⁶ m/s.
Explanation:
Given;
wavelength of the ultraviolet light beam, λ = 130 nm = 130 x 10⁻⁹ m
the work function of the molybdenum surface, W₀ = 4.2 eV = 6.728 x 10⁻¹⁹ J
The energy of the incident light is given by;
E = hf
where;
h is Planck's constant = 6.626 x 10⁻³⁴ J/s
f = c / λ
Photo electric effect equation is given by;
E = W₀ + K.E
Where;
K.E is the kinetic energy of the emitted electron
K.E = E - W₀
K.E = 15.291 x 10⁻¹⁹ J - 6.728 x 10⁻¹⁹ J
K.E = 8.563 x 10⁻¹⁹ J
Kinetic energy of the emitted electron is given by;
K.E = ¹/₂mv²
where;
m is mass of the electron = 9.11 x 10⁻³¹ kg
v is the speed of the electron
Therefore, the speed of the electron is 1.371 x 10⁶ m/s.
Answer:
Density of Sand is .
Explanation:
Given Empty Density bottle weighs 23.5gm(W=23.5gm)
Weight of bottle when completely filled water=48.4gm
So amount of water required to fill the bottle=Weight of bottle filled with water-W
Amount of water required to fill the bottle()=48.4gm-23.5gm
g
Since we know density of water and
We can calculate volume of empty space in the bottle(V).
V
V=
V=
V=24.9
Now bottle is partially filled with sand,and weight of bottle is ()36.5gm
So,
Amount of sand added ()=36.5-Weight of the bottle
=13g
After filling the bottle with water again,the weight of the bottle becomes (=56.5g)
Therefore,
amount of water added to the bottle of sand in grams = -36.5gm
amount of water added =56.5g-36.5g
amount of water added =20g
As the density of water = 1g/
Amount of water (in grams )=Volume of water occupied
20=volume of water added
Therfore volume of water added to the sand filled bottle()=20
As we know the total volume of the water bottle(V),
Volume of the sand occupied in the water bottle=V-
=24.9g-20g
=4.9g
We know,
Density=Mass/Volume
Therefore,
density of sand =
density of sand =
density of sand =