A surfactant used for cleaning is called a(n):________

The current scientific verdict on the phlogiston theory demonstrates which two of the following principles?

masha68 [24]

Answer:

The two valid principles are:

Scientific theories can be replaced by better theories.

An experiment can disprove a theory that scientists have accepted.

Explanation:

The scientific knwoledge is not inmutable; it may (and does) change with new discoveries.

In fact, scientific theories cannot be proved right, instead they are constantly tested to try to disprove them. This is what the principle that theories are falsiable means.

As long as a scientific theory is not disproved it remains valid, but new discoveries may lead, eventually, to its disprovement.

Scientific knowledge evolves because new procedures, new technologies, and new evidence leads to a better understanding and better explanations.

5 0

3 years ago

Part complete When a 235 92U nucleus is bombarded by neutrons (10n) it undergoes a fission reaction, resulting in the formation

nikdorinn [45]

Answer: The isotopic symbol of barium is $_{56}^{138}\textrm{Ba}$ and that of strontium is $_{38}^{89}\textrm{Sr}$

Explanation:

Nuclear fission reactions are defined as the reactions in which a heavier nuclei breaks down in two or more smaller nuclei.

In a nuclear reaction, the total mass and total atomic number remains the same.

For the given fission reaction:

$^{235}_{92}\textrm{U}+^1_0\textrm{n}\rightarrow ^A_Z\textrm{Ba}+^{94}_{36}\textrm{Kr}+3^1_0\textrm{n}$

To calculate A:

Total mass on reactant side = total mass on product side

235 + 1 = A + 94 + 3

A = 139

To calculate Z:

Total atomic number on reactant side = total atomic number on product side

92 + 0 = Z + 36 + 0

Z = 56

The isotopic symbol of barium is $_{56}^{139}\textrm{Ba}$

For the given fission reaction:

$^{235}_{92}\textrm{U}+^1_0\textrm{n}\rightarrow ^A_Z\textrm{Sr}+^{143}_{54}\textrm{Xe}+3^1_0\textrm{n}$

To calculate A:

Total mass on reactant side = total mass on product side

235 + 1 = A + 143 + 3

A = 90

To calculate Z:

Total atomic number on reactant side = total atomic number on product side

92 + 0 = Z + 54 + 0

Z = 38

The isotopic symbol of strontium is $_{38}^{89}\textrm{Sr}$

Hence, the isotopic symbol of barium is $_{56}^{138}\textrm{Ba}$ and that of strontium is $_{38}^{89}\textrm{Sr}$

7 0

3 years ago

The two elements discovered by Marie Curie are _____ and _____. uranium curium radium polonium

denpristay [2]

Marie Curie discovered polonium and radium. Hope this helps:))) Please, mark Brainliest!

5 0

3 years ago

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Elements may be individual atoms or they may form molecules. Compounds can only have which form? PLEASE ANSWER FAST WILL GIVE BR

son4ous [18]

Answer:

All compounds are molecules

I got you! i hope i helped

Explanation:

7 0

3 years ago

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The atomic mass of an element is the sum of neutrons and A) atoms. B) electrons. C) isotopes. D) protons.

Elis [28]

Answer: D) protons.

The other option that would make the most sense would be electrons, however the mass of an electron is so small that is basically negligible, so it's not included in the atomic mass.

3 0

3 years ago

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A surfactant used for cleaning is called a(n):_________.