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3 years ago

According to the law of conservation of matter, what number must be the same on each side of a chemical equation?

Physics

1 answer:

olga2289 [7]3 years ago

7 0

Answer:

4. The number of atoms of each element

Explanation:

Why is 1 wrong?

The number of substances (i.e. number of mols of substances) do not have to be the same. For instance, 2 mol of water reacts with 1 mol of oxygen to form 2 mol of water. Obviously the numer of substances is not conserved. Thus, it isn't a requirement.

Why is 2 wrong?

The number of chemical symbols do not mean anything. They do not tell us anything about the quantity of matter, they only tell us about the elements that are involved in the reaction.

Why is 3 wrong?

Once again, the number of chemical formulas are meaningless.

Why is 4 correct?

The number of atoms are always conserved as atoms cannot be broken or created.

Possible confusion...

The number of atoms are always conserved but the number of molecules may not always be conserved.

Why? As 2 atoms may be a molecule on the reactant side and 4 atoms may become a molecule on the product size, causing the number of molecules to reduce by half, while the number of atoms remain constant.

Hope that makes sense!

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D.) How can you demonstrate the magnetic force? Write with an example

Lena [83]

Explanation:

d) Magnetic force is the power that pulls materials together (magnet e. g iron)

an example :how magnet can pick up a coin.

e) frictional force produces when two surfaces are in contact with each other.

effects of friction : I) it produces heat

II) it causes loss in power.

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3 years ago

Objects can be charged by the transfer of electrons. True False

Sveta_85 [38]

Answer:

True

Explanation:

Whenever electrons are transferred between objects, neutral matter becomes charged. For example, when atoms lose or gain electrons they become charged particles called ions. Three ways electrons can be transferred are conduction, friction, and polarization. In each case, the total charge remains the same.

I tried, hope this helps :)

* I might be wrong though

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3 years ago

If the kinetic energy of a 10 kilogram object is 2000 joules It’s velocity is

Vika [28.1K]

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3 years ago

A typical 100-watt light bulb consumes 100 j of energy per second. If a light bulb converts all of this energy to 400 nm light

VladimirAG [237]

The missing question is: how many photons are produced per second?

Answer:

$2.0\cdot 10^{20}$

Explanation:

The energy of a photon is given by

$E_1 = \frac{hc}{\lambda}$

where

h is the Planck constant

c is the speed of light

$\lambda$ is the wavelength of the photon

In this problem, the photons have wavelength

$\lambda = 400 nm = 400 \cdot 10^{-9} m$ , so each photon has an energy of

$E_1 = \frac{(6.63\cdot 10^{-34})(3\cdot 10^8)}{400\cdot 10^{-9}}=4.97\cdot 10^{-19} J$

The total energy emitted by the bulb in 1 second is

E = 100 J

Therefore, the number of photons emitted per second is

$n=\frac{E}{E_1}=\frac{100}{4.97\cdot 10^{-19}}=2.0\cdot 10^{20}$

3 0

3 years ago

Which particle is used as a beam to treat cancer? electrons protons neutrons

Arisa [49]

Answer: protons

Explanation:

Protons are positively charged elementary particles of hydrogen atom nuclei, and have a much greater weight than that of electrons.

In this sense, proton therapy consists in pointing to a tumor with an invisible and highly controlled beam that works with precision as if it were drawn with the tip of a pencil.

It should be noted that, firstly protons are accelerated inside a cyclotron at a speed that is equal to approximately half the speed of light (allowing them to have high energy) allowing the damage to tumors up to a depth of approximately 30 cm.

After the protons are accelerated in the cyclotron, they are directed with a strong magnetic field to a very narrow beam and transferred with a high degree of precision through the malignant tumor. This high amount of energy released in a controlled manner in the tumor tissue, results in ionization and damage to the DNA of the malignant cells that are attacked, causing them to stop dividing rapidly (the cause of cancer) or even causing the cells to die, immediately

This is a highly effective treatment that has no side effects in damage to healthy tissue surrounding the tumor, unlike X-ray therapies.

5 0

3 years ago

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