Please help I’ll put u Brainlyiest.

arlik [135]

Answer: Star formation begins when the denser parts of the cloud core collapse under their own weight/gravity. These cores typically have masses around 104 solar masses in the form of gas and dust. The cores are denser than the outer cloud, so they collapse first.

Hope this helped! :))

7 0

4 years ago

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What causes valley air to move up surrounding mountains during the day?

AleksandrR [38]

Answer:

so the third one

Explanation:

During the day, the sun heats up mountain air rapidly while the valley remains relatively cooler. Convection causes it to rise, causing a valley breeze. At night, the process is reversed. During the night the slopes get cooled and the dense air descends into the valley as the mountain wind.

7 0

3 years ago

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Nitrobenzene contains 5 hydrogen atoms, 6 carbon atoms, 2 oxygen atoms, and 1 nitrogen atom. what is the chemical formula for ni

ollegr [7]

C₆H₅NO₂

<h3>Further explanation</h3>

Nitrobenzene contains:

5 hydrogen atoms,
6 carbon atoms,
2 oxygen atoms, and
1 nitrogen atom.

The chemical formula for nitrobenzene is C₆H₅NO₂.

Nitrobenzene is one of benzene derivatives, precisely including the type of monosubstituted benzenes.

The molecular structure of phenyl $\boxed{ \ C_6H_5- \ }$ is formed by removing one H atom from the benzene $\boxed{ \ C_6H_6 \ }$ molecule. A substituent is bound to the C atom which loses the H atom so it is called monosubstituted benzene.

In the naming of monosubstituted benzenes, benzene is the parent name and the substituent is indicated by a prefix.

nitro is the substituent
benzene is the parent name

When benzene is reacted with a mixture of concentrated nitric acid and concentrated sulfuric acid, it yields nitrobenzene.

$\boxed{ \ C_6H_6 + HNO_2 \ (with \ H_2SO_4 \ in \ 30^0C-40^0C) \rightarrow C_6H_5NO_2 + H_2O}$

- - - - - - -

<u>Notes:</u>

Benzene and compounds having similar chemical properties to benzene are called aromatic compounds.
Benzene is a colorless, poisonous liquid with a specific odor. it dissolves in organic solvents in organic solvents such as alcohol, ether, and acetic acid. Benzene is also good for non-polar substances.
Nitrobenzene is used in the manufacture of aniline and other organic chemicals. Nitrobenzene is a pale yellow, oily, and highly toxic liquid with the odor of bitter almonds.

<h3>Learn more</h3>

Calculating the pH value of weak base brainly.com/question/9040743
About the solution as a homogeneous mixture brainly.com/question/637791
About the mass and density of substances brainly.com/question/4053884

Keywords: nitrobenzene, contains, 5 hydrogen atoms, 6 carbon, 2 oxygen, and 1 nitrogen. the chemical formula, benzene, monosaturated, phenyl, aromatic compounds

7 0

3 years ago

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Lithium salts are often much less soluble in water than the corresponding salts of other alkali metals. For example, at 18°C, th

serious [3.7K]

Lithium is one of element of group 1 of periodic table.

Lithium has the smallest radius than as compared to the other elements, thus the density of the alkali metal is also less.

Lithium when added to water it floats, because of lower density. It eventually fizzes and becomes smaller.

The reaction on lithium and water is:

2Li + 2H₂O --> 2LiOH + H₂ (g)

The hydrogen gas which is liberated is highly flammable.

Thus, lithium salts are insoluble in water.

Density is defined as the mass of a substance per unit volume.

Density = Mass ÷ Volume.

To know more about Alkali metals, refer to this link:

brainly.com/question/5063184

#SPJ4

8 0

2 years ago

Draw the structure of the compound C9H10O2 that might exhibit the 13C-NMR spectrum below. Impurity peaks are omitted from the pe

zhenek [66]

Complete question

Draw the structure of the compound $C_{9}H_{10}O_{2}$ that exhibits the $^{13}C-NMR$ spectrum shown on the first uploaded image(on the second and third uploaded image is closer look at the $^{13}C-NMR$ spectrum ) . Impurity peaks are omitted from the peak list. The triplet at 77 ppm is $CDC_{l3}$ .

Answer:

The structure that might exhibit the $^{13}C-NMR$ spectrum is shown on the fifth uploaded image

Explanation:

In order to get a good understanding of the answer above we need to know that

• Proton NMR spectrum: proton NMR spectroscopy is one of the techniques, which is useful to predict the structure of the compound.

• In $^{\rm{1}}{\rm{H NMR}}$ spectroscopy, peaks are observed at the point where the wavelength of proton nuclei matched to substance nuclei wavelength.

• In same manner there are other spectroscopies are present like $^{{\rm{13}}}{\rm{C NMR}}$

, IR and mass spectroscopy.

• Infrared spectroscopy is used to determine the functional groups present in a compound.

• Infrared bands observed when there is change in dipole moment occurs between the atoms. Infrared bands describe about the bond stretches, which causes due to the dipole moment present in the molecule.

Fundamentals

Double bond equivalence: number of double bonds or number of rings in the structure can be calculated by using double bond equivalence formula.

$DBE = N_{c} + 1 - (\frac{N_{H}+N_{Cl}-N_{N}}{2}})$

Where,

$N_{c} =$ number of carbon atoms

$N_{H}=$ number of hydrogen atoms

$N_{Cl} =$ number of chlorine atoms

$N_{N}=$ number of nitrogen atoms

The table for the $^{{\rm{13}}}{\rm{C NMR}}$ is shown on the fourth uploaded image

Molecular formula of the compound is ${{\rm{C}}_9}{{\rm{H}}_{{\rm{10}}}}{{\rm{O}}_{\rm{2}}}$

Double bond equivalence of the compound is calculated below.

$DBE = N_{c} + 1 - (\frac{N_{H}+N_{Cl}-N_{N}}{2}})$

Where,

$N_{c} =$ 9

$N_{H}=$ 10

$N_{Cl} =$ 0

$N_{N}=$ 0

$DBE = N_{c} + 1 - (\frac{(10+0) -0}{2}})$

$DBE =5$

Therefore, the compound has five double bonds, which indicating that there is chance of getting aromatic rings too.

Note:

Double bond equivalence is calculated as 5 which indicates that there are 5 double bond (may rings) in the structure of the compound.

Double bond equivalence is calculated by using this formula.

$DBE = N_{c} + 1 - (\frac{N_{H}+N_{Cl}-N_{N}}{2}})$

13C NMR data of the compound is explained below.

1.A peak at 166.5 ppm, which indicates the presence of ester group

2.Peaks at 132.7, 130.5, 129.5, 128.2 ppm (aromatic carbons) are indicating a mono substituted aromatic ring

3.A peak at 60.9 ppm means methylene group attached to oxygen atom

4.A peak at 14.3 ppm, which indicates the presence of methyl group

According to this data and the using the double bond equivalence, structure of the compound shown on the fifth uploaded image .

Note:

According to given spectral data, structure of the compound has been predicted. It is clear that; -ester functional group is present in the structure because there is a peak at 166.5ppm. According to given proton $^{13}C NMR$ data, above structure has been drawn. Therefore, the compound is ethyl benzoate.

7 0

4 years ago