Think critically...
Q7. Bridges are made from materials that contract and expand as the temperature changes, so
they cannot be fastened firmly to the bank of a river or lake. The photographs below show an
expansion joint at the end of a bridge in winter and in summer.
www
(A)
(B)
Which season is shown in each picture? Explain how you know?

The molecular mass of MgCO3 is 84.313 grams/mol.

The relative molecular mass of MgCo3

Symbol          Mg                               C                                O

Atoms             1                                  1                                 3

Name         Magnesium                  Carbon                      Oxygen

Atomic            12                                6                                 8

Molar Mass   24.305                      12.011                        15.999  

Total              24.305                      12.011                        47.997=84.313

The molecular mass of MgCO3 is 84.313 grams/mol.

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The major product is p-bromo N,N,N -trimethylaniliniumiodide when p-bromoaniline react with excess CH₃I.

When p-bromoaniline react with methyl iodide it produces p-bromo N,N-dimethylaniline.

When  p-bromo N,N-dimethylaniline reacts with excess methyl iodide leading to the production of p-bromo N,N,N -trimethylaniliniumiodide.

Thus from the above conclusion we can say that The major product is p-bromo N,N,N -trimethylaniliniumiodide.  when p-bromoaniline react with excess CH₃I.

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Answer:

you better give me brainliest

Explanation:

Zinc nitrate and calcium nitrate solution can be distinguished by reaction with ammonium hydroxide. Zinc forms a white gelatinous ppt. whereas there is no precipitation of calcium hydroxide even with excess of ammonium hydroxide

Answer:

You can separate a mixture of sand, salt and water by decantation and evaporation. Decantation will separate sand from salt and water. Sand remains in the original vessel, whereas salt and water is transfered to new vessel. Evaporation will separate salt from water.

The hypothesis should be; "Increasing the amount of ice increases the rate at which the ice will melt"

The term hypothesis refers to a tentative explanation that could be applied in order to explain an observation. When we give a hypothesis, it must be subjected to rigorous experimentation thus it can be confirmed or repelled by experiment.

Now, we can see that the question here is; "How does the amount of salt added to ice affect the rate at which the ice will melt?" This implies that the correct hypothesis here ought to have to do with the impact of the amount of ice in the affirmative.

Thus, the hypothesis should be; "Increasing the amount of ice increases the rate at which the ice will melt"

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Chemistry deals with elements and compounds. The properties of matter, changes to matter, and composition of matter are studied in chemistry. Thus, options a, b, and d are correct.

Chemistry is said to be a scientific field under natural sciences that studies the structure, properties, and composition of matter.  It includes atoms, elements, and compounds.

The chemistry includes topics like the properties of matter, including the volume, density, temperature, etc., changes to a matter involving condensation, freezing, vaporization, melting, etc.

The composition of matter including the sub-atomic levels is studied in chemistry. Whereas, the interactions between living things are studied in biology.

Therefore, options a, b, and d. the properties, changes, and composition are studied in chemistry.

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The elements of group IA have been termed alkali metals because of their oxides and hydroxides form alkaline.

An element can be defined as a substance which cannot be split into simpler units by ordinary chemical process

Below are some examples of elements:

Alkali metals refers to any of the soft, light, reactive metals of Group 1 of the periodic table.

Periodic table refers to a tabular chart of the chemical elements according to their atomic numbers so that elements with similar properties are in the same column.

So therefore, the elements of group IA have been termed alkali metals because of their oxides and hydroxides form alkaline.

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The temperature of the chemistry book decreasing as the chemistry book slides across it is the difference when motion is slower.

What is Temperature?

Temperature is a unit used to convey hotness or coolness. It can be stated in terms of any number of arbitrary scales and indicates the direction in which heat energy will naturally flow, i.e., from a hotter body to a cooler body (one at a lower temperature). Temperature is not the same as the energy of a thermodynamic system; for instance, an iceberg has a significantly larger total heat energy than a match, despite the fact that a match is burning at a much higher temperature.

What is relation between motion and temperature ?

When motion is slow , there is an decrease in friction and decrease in thermal(heat) energy which leads to decrease in temperature.

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Answer:

The speed of the particles of the chemistry book increases when the chemistry book slides across the physics book.

Explanation:

edmentum

Answer:

a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change

a catalyst is a substance that increases the speed of reaction by lowering the activation energy or providing an alternative pathway of a lower activation energy(more likely for enzymes in bio).

it also doesnt take part in the reaction but in chemistry, there are homologous and homogenous catalysts where some may take part in the rxn BUT they are regenerated and are not used up

chem: more particles will have the energy to overcome the activation energy, resulting in a higher frequency of effective collision, so the rate of rxn ↑. (usually catalyst is transition metal)

bio: enzyme-substrate complex, where it is essentially what happens in the chemistry part above but the conclusion is that it takes lesser time for nutrients to be broken down and therefore digested.

Leucine and methionine are the amino acids formed using the n-phthalimido malonic ester synthesis.

The steps involved in phthalimido malonic ester synthesis:

Step 1: Deprotonation To Give An Enolate

In the first step, a base (CH3O– in this case) removes the most acidic proton from the ester (on C2 here, with a pKa of about 13) to give an enolate. The resulting enolate can be drawn as one of two resonance forms.

Step 2: SN2 Reaction Of The Enolate Nucleophile With An Alkyl Halide Electrophile.

Enolates are great nucleophiles. In the second step, the enolate acts as a nucleophile in an SN2 reaction to form a new C-C bond.

Step 3: Acidic Ester Hydrolysis

Acid and water are added to perform the aqueous hydrolysis of the ester to a carboxylic acid.

Step 4: Decarboxylation To Give An Enol

When carboxylic acids have a carbonyl group (C=O) two bonds away, they can readily lose carbon dioxide, because the carbonyl can act as an electron “sink” for the pair of electrons coming from the breaking C–C bond, forming an enol. This is called “decarboxylation”. Note how this is also the case for carboxylic acids with a ketone two bonds away, so-called “β-keto acids”.

Step 5: Tautomerization Of The Enol Back To The Carboxylic Acid

The enol that is formed is not a stable species. It can undergo transformation into its constitutional isomer: in this case, a carboxylic acid. These two constitutional isomers are in equilibrium with each other, although the “keto” form (with the carbonyl group) is greatly favoured. This process is called "tautomerism".

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Answer is although the question should have 3 significant figures.

Fe + CuSO4 --> Cu + FeSO4

It is already balanced

1 mol Fe : 1 mol CuSO4 : 1 mol Cu : 1 mol FeSO4

Fe: 55.8 g/mol

Cu: 63.5 g/mol

number of moles = mass in grams / atomic mass = 93.7 g / 55.8 g/mol = 1.679 mol

1 mol Fe / 1 mol Cu => 1.679 mol Fe / 1.679 mole Cu

mass = atomic mass * number of atoms = 63.5 g/mol * 1.679 moles = 106.6 g = 107 rounded to 3 significant figures.

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There are  34  protons , 45 neutrons and 36 electrons, in that order are present in the anion formed by one atom of 79Se .

Calculation

The number of electron / protons ( present in the nucleus ) of the atom is equal to atomic number .

The sum of  number of electron / protons ( present in the nucleus ) and neutrons  ( present in the nucleus )  of the atom is called atomic mass.

The atomic number of Se = 34

The Mass number or atomic mass of Se = 79

The anion of Se = [tex]Se^{-2}[/tex]

It means two electron loss by Se and form  [tex]Se^{-2}[/tex] .

So , the difference between number of electrons and protons = 2

Hence , number of electron and proton in  [tex]Se^{-2}[/tex] anion is 34 ( two less than number of protons ) and 36

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It is important to know if a substance is a molecular compound or an ionic compound because the boiling and freezing points of a solvent are colligative properties, and they depend on the solute particles.

Molecular compounds are pure things called that are created when atoms are joined by the sharing of electrons. Ionic compounds are formed by transferring electrons between the elements.

It is important to know the type of compounds before predicting because the more the solute particles the more the freezing point and lower the boiling points. And it tells how much amount f solute will be fine in the solvent.

Thus, knowing if a material is a molecular or ionic compound is crucial since a solvent's boiling and freezing temperatures are collaborative features that are dependent on the solute particles.

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Excess alcohol is removed by Vacuum filtration.

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If you were given the the total # of grams of all three compounds with the % of each molecular compound - H2O, CO2 and sugar [you would need to know the type of sugar in the Pop such as C12H22O11 as to find its MM (molar mass)]

To begin take the % of each compound x the total grams of all the compounds. For illustrative purposes let's say it works out to be 50 grams of H2O in the POP. The same would be. done for CO2 and for the sugar.

Step 1) With the mass of each you could determine the # of moles of each:

Example if the number grams of water in the sample is 50g, to determine the # of moles of water you would do the following - 50g H20 x 1 mol/18g H20 = 2.8 mol H2O The same technique would be used for the other compounds to find the # of moles.

Step 2) To find the representative particles of each(molecules, atoms) you would do the following:

as the example given of above for H20 - 50 grams you calculated as shown above to be the number of mol of H20 = 2.8mol

From the number of mol of H20, to determine the # of molecules of water you would set up the following:

2.8 mol H20 x 6.02 x 10^23/1 mol H2O = 1.69 X 10^24 molecules of H20.

The same would be done for CO2 and the sugar.

Step 3) Now to find the number of atoms of element of the compound taking for example the H2O example above:

Take the # of molecules of H2O found above and set it up in the following manner:

1.69 X 10^24 molecules H2O x 2 atoms H/1 molecule H2O = 3.38 x 10^24 atoms H

1.69 x 10^24 molecules H2O x 1 atom O)/1 molecule H2O = 1.69 X 10^24 atoms O

The same would be done for CO2 and for the sugar compound.

The intermolecular forces are present between the molecules and allow their interactions. The ion-dipole force is present between the water and the chloride ion.

Ion-dipole intermolecular forces are present when the molecules have an ion and a neutral molecule that can interlink through an electrostatic attraction. These forces are present in solutions.

The chloride ions have a negative charge, whereas the water molecule has a neutral charge. Water is a polar molecule that has a partial negative and positive charge that can bond with the anion (chloride ion).

Therefore, the water and the chloride ions have ion-dipole intermolecular forces.

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Answer:

The low light eye sight depends on the rod cells of the eye,and the birds have more amount of rod cell in their eyes, that's why they have an extraordinary night vision

Answer:

Red

Explanation:

Red color is evidenced when thymol blue indicator is in a solution having a pH of 11. A pH of 11 means that the solution is basic or alkaline. Therefore, the indicator turns red, indicating that the solution is alkaline.

When thymol blue indicator is in a acidic solution, the indicator remains blue.

the nitrogen and the carbon are sharing six electrons! A single bond is created when two atoms share two electrons. If they share four, their bond is doubled. These two are actually sharing a six, which is a triple bond.

By sharing four pairs of electrons through the formation of four covalent bonds, carbon fills its outer energy level and achieves stability.

Only the nitrogen atoms' valence shells are taken into account while thinking about the bonding in a nitrogen molecule. Eight electrons can fit in total in nitrogen's outer shell. Therefore, the nitrogen atoms share three electrons each in order to produce the most stable structure.

One of the most frequent bonds in organic chemistry and biochemistry is the covalent bond between carbon and nitrogen. With five valence electrons, nitrogen is trivalent in simple amines, with the two extra electrons forming a lone pair.

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The corresponding concentration values of OH⁻  for the pH values

of following are -

1- 10⁻¹

3- 10⁻³

5- 10⁻⁵

7- 10⁻⁷

9-  10⁻⁹

11- 10⁻¹¹

pH is a logarithmic measure of the hydrogen ion concentration of an aqueous solution pH = -log[H+]

pH describes how acidic or basic an aqueous solution is, where a pH below 7 is acidic and a pH greater than 7 is basic. pH of 7 is considered neutral .

Functions of OH−    :

OH− functions as a base .

Hydroxide is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a single covalent bond, and carries a negative electric charge.

Hence, this way pH values of these concentrations are mentioned .

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A molecular orbital that decreases the electron density between two nuclei is said to be antibonding.

The bonding orbital, which would be more stable and encourages the bonding of the two H atoms into [tex]H_{2}[/tex], is the orbital that is located in a less energetic state than just the electron shells of the separate atoms. The antibonding orbital, which has higher energy but is less stable, resists bonding when it is occupied.

An asterisk (sigma*) is placed next to the corresponding kind of molecular orbital to indicate an antibonding orbital. The antibonding orbital known as * would be connected to sigma orbitals, as well as antibonding pi orbitals are known as [tex]\pi[/tex]* orbitals.

Therefore,  molecular orbital that decreases the electron density between two nuclei is said to be antibonding.

Hence, the correct answer will be option (b)

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 overall equation is ,

2FeSo4+heat→Fe203+SO2+SO3

Decomposition reaction is when Reactant break down into simpler parts .

For decomposition reactions require energy input. The decomposition reaction happens in our everday life. The process of digestion food is a type of decomposition ,where breakdown of food from larger to smaller particles and large amount of energy release.

The decomposition is classified into

*thermolysis

*Electrolysis

*photolysis

The overall equation will be

2FeSo4+heat→Fe2O3+SO3+So2

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Lithium metal reacts with nitrogen gas to form lithium nitride the balanced chemical equation will be 6Li + N₂ → 2Li₃N.

In a balanced chemical reaction, the number of moles that are present at the side of the reactant must be always equal to the side of product formation this is known as a balanced chemical equation.

The balanced chemical reaction will be 6Li + N₂ → 2Li₃N.

Here 6 moles of lithium is reacting with one nitrogen but as it is in gaseous state it is N₂ after reacting with lithium it will give two moles

Therefore, balanced equation will be 6Li + N₂ → 2Li₃N

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In the polymerization reaction, the lone pair electrons on the NH₂ groups of hexanediamine attack the C=O groups of the dicarboxylic acid in a nucleophilic substitution reaction as shown in the image.

Hydroxide is added to remove any H⁺ ions present and keep the hexanediamine in the deprotonated form, so that the NH₂ lone pair electrons are available for reaction.

If hydroxide is not added, the NH₂ groups will get protonated by H⁺  ions present to give NH₃⁺ groups, which cannot react.

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The volume of ethyl alcohol overflow will be 9.265mL.

To calculate the volume of ethyl alcohol overflow, we will use

∆V=V(á∆T)

Where,

∆V=volume expand

á=volumetric expansion Coefficients =0.00109/°C

V=initial volume =500ml

T'=final temp. =22°C

T=initial temp=5°C

Now,

∆V=500×(0.00109/°C) ×(22-5)

=500×(0.00109) (17)

=9.265ml

Thus, we find that the volume of ethyl alcohol overflow will be 9.265 mL.

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The balloon is filled with 0.5L of air at sea level and submerged to a depth. Since, there is no change in the Temperature, the process is Isothermal. It is a process in which the temperature T of the given system does not change and remains constant. Hence, ΔT=0

Any system in which the temperature is kept constant is stated as an Isothermal Process. Since, in the given question, Temperature is not changing, hence we can consider it to be an Isothermal Process.

Given:

Pressure at sea level, P₁= 1 atm

Volume at sea level, V₁= 0.5L

Pressure at depth, P₂= 3.25 atm

Volume at depth, V₂= ?

Since, the process is Isothermal, hence,

∴ P₁V₁ = P₂V₂

⇒ 1 × 0.5 = 3.25 × V₂

⇒ V₂ = 0.5/3.25

⇒ V₂ = 0.154L

So, the Volume of balloon at the depth is 0.154L.

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The volume of the balloon at an altitude where the pressure is 530 torr if the temperature remains constant is 4.33 L

Calculation,

According to Boyle law, the pressure of a given quantity of gas varies inversely with its volume at constant temperature.

[tex]P_{1} V_{1} =k[/tex]            .....(i)

[tex]P_{1}[/tex]  is initial pressure =765 torr

[tex]V_{1}[/tex] is initial volume = 3L

k is constant

[tex]P_{2} V_{2} =k[/tex]             ....(ii)

[tex]P_{2}[/tex] is final pressure = 530 torr

[tex]V_{2}[/tex]  is final volume =?

k is constant

Combining equation (i) and (ii). we get,

[tex]P_{1} V_{1} =P_{2} V_{2}[/tex]

765 torr × 3L= [tex]V_{2}[/tex]  ×530 torr

[tex]V_{2}[/tex]   =  765 torr × 3L/530 torr = 4.33 L

Boyle law used during respiration or breathing.

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Answer:

An increase in the intensity of sounds or fire issuing from a relief valve.

Propane serves as the propellant in all aerosols. R-12, a Freon that was the previous propellant, has been outlawed because it harms the ozone layer above the poles. Propane and R-12 share the same pressure-temperature characteristics.

Propane's boiling point is quite low. It desires a boil-off at ambient temperature. And it continues to do so until the pressure inside a closed container rises to roughly 150 psi (give or take depending on temperature), at which time the boiling point is raised high enough to cause the substance to stop boiling.

"Contents Under Pressure" is exactly what the notice indicates. Paint, hairspray, lubricant, wasp and hornet spray, among other liquids, can be found within an aerosol can, which is a pressure vessel. By inspecting the bottom, you may determine whether a vessel is a pressure vessel. If it is dished in like a bowl, it has the same pressure-holding end as a huge propane tank, with the exception that the curve on the latter has an outward orientation. On aerosol canisters, it is inward because they must sit upright for ease. A circular bottom just cannot accomplish that. But the top resembles an outer hemisphere more or less.

Thank you,

Eddie

An overpack containing four one-liter metal cans of NA1993, Compounds, cleaning liquid, a Class 3 (Flammable liquid), PG III, being offered for transportation by highway, may qualify for specification packaging. This is further explained below.

Generally, The term "specification packaging" refers to a package that meets one of the packaging specifications or standards listed in this subchapter's parts 178 or 179.

In conclusion, It's possible that an overpack that contains four metal cans of one liter each filled with NA1993, Compounds, cleaning liquid, a Class 3 (Flammable liquid), PG III, and that's being provided for transportation on the highway might qualify as specified packing.

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