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a)
b)
c)
d)

Answer:

Calcular la molaridad de una solución que se preparó disolviendo 14 g de KOH en suficiente  

agua para obtener 250 mL de solución. (masa molar del KOH = 56 g/mol).

Resolución: de acuerdo a la definición de “molaridad” debemos calcular primero, el número de mol de soluto (KOH) que  

se han disuelto en el volumen dado, es decir, “se transforma g de soluto a mol de soluto” por medio de la masa molar,  

así:

56 g de KOH 14 g de KOH

----------------- = ------------------- X = 0,25 mol de KOH

1 mol X

Ahora, de acuerdo con la definición de molaridad, el número de mol debe estar contenido en 1000 mL (o 1 L) de  

solución, que es el volumen estándar para esta unidad de concentración, lo que se determina con el siguiente planteamiento:

0,25 mol X

----------------------- = ------------------------- X = 1 mol de KOH

250 mL de solución 1000 mL de solución

Explanation:

Answer:

B. The atom

Explanation:

Cells are the most basic unit of structure and the smallest unit of matter is the atom.

Answer:

B. The atom

Explanation:

yeee it was right

Answer:

Tapeworms and roundworms both belong to the same phylum however, their families are different from one another.

Tapeworms are flat, segmented intestinal parasites of the cat and dog and humans sometimes. They are present in the intestines of pets and depend on them, therefore, are parasites. These parasites look like tape which gives it its name.

Roundworms can also infect humans and the most common cases are among children. When not treated immediately, they can cause severe damage to a human host and can even cause blindness. Tapeworms are white in color with a long, segmented body.

Answer:

Hence the solids that should test to investigate the effects of cations on pH is

[tex]AlBr_{3}[/tex] (Cation is Al 3+)  

[tex]MgCl_{2}[/tex]  ( Cation is Mg 2+)  

[tex]CH_{3} NH_{3} Br[/tex] ( Cation is NH2+).

Explanation:

The solids in the following should you test to investigate the effects of cations on pH.  

[tex]AlBr_{3}[/tex] contains (Cation is Al 3+)  

[tex]MgCl_{2}[/tex] contains ( Cation is Mg 2+)  

[tex]CH_{3} NH_{3} Br[/tex] contains( Cation is NH2+ )

The atoms or the molecules containing the positive charge that gets attracted to the cathode are called cations. The compounds a. [tex]\rm AlBr_{3}[/tex], c. [tex]\rm MgCl_{2}[/tex] and e. [tex]\rm CH_{3}NH_{3}Br[/tex] should be investigated.

Cations are the positive charge containing molecules and atoms that have more protons in their nucleus than the number of electrons in their shells. They are formed when they lose one or more electrons to another atom.

The addition or release of the electrons of the cations and anions affects the pH system as absorption of the cation decreases the pH and absorption of the anions increases the pH.

Hence, [tex]\rm Al^{3+}[/tex], [tex]\rm Mg^{2+}[/tex] and [tex]\rm NH^{2+}[/tex] are the cation that should be investigated. The addition of the cations will reduce the pH of the reaction.

Therefore, absorption of the cation reduces the pH.

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Answer:

In styrene, there is a phenyl group which is electron-withdrawing. So the electronic density in the double bonds increases, hence easy to associate as monomers. While in methoxystyrene, there is a carbonyl group which is not electron deficient. so no easy association with monomers.

Explanation:

[tex]{ \sf{styrene \: is \: phenylethene \: }} \\ { \sf{its \: polymer \: is \: polystyrene}}[/tex]

1.42liters, which is equivalent to 3pints, of blood is required for the surgery

1 US pint = 0.473 liters

3 × 0.473

= 1.419 liters of blood for the surgery

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To convert from mass concentration to molar concentration we use the formula;

Mass concentration = molar concentration * molar mass

Molar concentration of Na2SO4 = 0.700 M

Molar mass of Na2SO4  = 2(23) + 32 + 4(16) = 142 gmol-1

Hence;

Mass concentration = 0.700 M * 142 gmol-1

Mass concentration = 99.4 g/mol

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Explanation:

to find the number of moles for tetracycline you use the formula,

number of moles=mass/molar mass

the mass is given in the question which is 71.9g and the molar mass is 444.43(you find I by adding the number of atoms for each element in the compound,12×22+1×24+14×2+16×8)

n=71.9g/444.43

=0.16g/mol

I hope this helps

Answer:

Solution temperature.

Explanation:

Hello there!

In this case, considering this question about chemical kinetics, it will be possible for us to analyze two perspectives:

1. Molecular: here, we infer that the solution temperature will provide more energy to the molecules in order to undergo more effective crashes which will make more products and therefore, increase the rate constant.

2. Mathematical: by means of the Arrhenius equation, it will be possible to tell that the increase in the temperature of the system, the negative of the exponent present in such equation will increase and therefore turn the rate constant bigger.

In such way, we infer the answer is solution temperature.

Regards!

Answer:

Solution given:

1 mole of KCl[tex]\rightarrow [/tex]22.4l

1 mole of KCl[tex]\rightarrow [/tex]74.55g

we have

0.14 mole of KCl[tex]\rightarrow [/tex]74.55*0.14=10.347g

74.55g of KCl[tex]\rightarrow [/tex]22.4l

10.347 g of KCl[tex]\rightarrow [/tex]22.4/74.55*10.347=3.11litre

volume of each solution contains 0.14 mol of KCl contain 3.11litre.

[tex]\:[/tex]

1 mole of KCl → 22.4l

1 mole of KCl → 74.55g

we have

0.14 mole of KCl → 74.55*0.14=10.347g

74.55g of KCl  → 22.4l

10.347 g of KCl → 22.4/74.55*10.347=3.11litre

volume of each solution contains 0.14 mol of KCl contain 3.11litre.

Answer:

Hence the correct option is an option (b) Sr4, Cl,Br−,Na+.

Explanation:    

Bromine and chlorine belong to an equivalent group. As we go down the group the dimensions increases which too there's a charge on the bromine atom. therefore the size of the Br- is going to be larger in comparison to the chlorine atom.

Sr atom is within the second group, and also it's below the above-mentioned atoms.so Sr is going to be the larger one among all the atoms.

Sodium and chlorine belong to an equivalent period .size decrease from left to right. but due to the charge on sodium its size decreases and there's an opportunity that Na+ size could be adequate for Cl.      

Here we finally assume that two atoms are of an equivalent size (Na+ and Cl) which are less in size compared to the opposite two(Sr and Br-) during which one is greater (Sr)and the opposite is smaller(Br-).

Answer:

Choice A. [tex]\rm H_{2}[/tex] would be produced at the negative electrode.

Explanation:

Ionic equation for this reaction:

[tex]2\, {\rm K^{+}} + 2\, {\rm Cl^{-}} + {2\, \rm H_{2} O} \to {\rm H_{2}} + {\rm Cl_{2}} + 2\, {\rm K^{+}} + {\rm 2\, OH^{-}}[/tex].

Net ionic equation:

[tex]2\, {\rm Cl^{-}} + 2\, \rm H_{2} O} \to {\rm H_{2}} + {\rm Cl_{2}} + 2\, {\rm OH^{-}}[/tex].

Half-equations:

[tex]2\, {\rm Cl^{-}} \to {\rm Cl_{2}} + 2\, {e^{-}}[/tex].

(Electrons travel from the solution to an electrode.)

[tex]2\, {\rm \overset{+1}{H}_{2} O} + 2\, {e^{-}} \to \overset{0}{\rm H}_{2} + 2\, {\rm O\overset{+1}{H}\!^{-}}[/tex].

(An electrode supply electrons to the solution to reduce some of the [tex]\rm H[/tex] atoms from [tex]\rm H_{2}O[/tex].)

In a DC circuit, electrons always enter the circuit from the negative terminal of the power supply and return to the power supply at the positive terminal.

The negative electrode is connected to the negative terminal of the power supply. Electrons from the power supply would flow into the solution through this electrode.  

This continuous supply of electrons at the negative electrode would drive a reduction half-reaction. In this question, that corresponds to the reduction of water: [tex]2\, {\rm \overset{+1}{H}_{2} O} + 2\, {\rm e^{-}} \to \overset{0}{\rm H}_{2} + 2\, {\rm O\overset{+1}{H}\!^{-}}[/tex]. Hence, [tex]\rm H_{2}[/tex] would be produced at the negative electrode.

The best option for dissolving PbBr₂ is option (2)

2) Add a solution of NaBr

The reason for choosing the above option is as follows;

Lead (II) bromide is an inorganic powdery substance that has a solubility in water of 0.973 g/100 mL at 20°C. It is insoluble in alcohol but is soluble in alkali, ammonia, NaBr, and KBr.

PbBr₂ is slightly soluble in ammonia, and it reacts with NaOH to produce Pb(OH)₂ and NaBr.

Taking the solubility product of PbBr₂ as [tex]K_{sp}[/tex] = 6.60 × 10⁻⁶, in a solution of 0.5 M NaBr, we have;

PbBr₂ → Pb⁺ + 2Br⁻

[tex]K_{sp}[/tex] = [Pb]·[2Br]²

Therefore, we get;

6.60 × 10⁻⁶ = [x]·[0.5]²

Where;

x = The number of moles of lead, Pb, in per liter of solution

∴ x = (6.60 × 10⁻⁶)/[(0.5 )²] = 2.64 × 10⁻⁵.

The molar solubility of PbBr₂ per liter of NaBr, x = 2.64 × 10⁻⁵ mol/L

PbBr₂ is more soluble in NaBr.

Given that ammonium ion NH₄Br  in water gives similar products to ammonia, NH₃, it is expected to be more suitable to dissolve PbBr₂ in NaBr.

Therefore, the best solution for dissolving PbBr₂(s) is NaBr, the correct option is option (2) add a solution of NaBr.

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Spontaneous generation theory is that living organisms can arise by non living things.

This theory follows the concept of abiogenesis where there is non living parent for a living child.

The appearance of maggots from rotten meat is the idea of abiogenesis, this creates a living organism with a dead parent.

The rotten piece of meat is a non living object but still maggots were formed from this.

Therefore the correct answer is B.

Answer:

a

Explanation:

Answer:

volume versus temperature, because they are also directly proportional.

Explanation:

Just took the test!

Answer:

It's D.  On the surface of the solid.

Explanation:

If the reactant is a solid, the surface area of the solid will impact how fast the reaction goes. This is because the two types of molecule can only bump into each other at the liquid solid interface, i.e. on the surface of the solid. So the larger the surface area of the solid, the faster the reaction will be.

Answer:

Radical chain initiator

Explanation:

The peroxide here serves as a radical chain initiator. In the field of chemistry the radical initiatives are those substances that are used in industrial processes like polymer synthesis. These initiatives have weak bonds generally and they're mostly used to create free radicals. These radicals are atoms that have odd numbers of electrons. Peroxide is an example of such.

Answer:

Covalent bonding and non-covalent bonding

Answer:

yes it is corrwect iyt is absolitle correct

Explanation:

Answer:

1.12 mol/L.

Explanation:

From the question given above, the following data were obtained:

Mole of LiCl = 3.75 moles

Volume = 3.36 L

Molarity =?

Molarity is simply defined as the mole of solute per unit litre of the solution. Mathematically, it is expressed as:

Molarity = mole / Volume

With the above formula, we can obtain the molarity of the solution as follow:

Mole of LiCl = 3.75 moles

Volume = 3.36 L

Molarity =?

Molarity = mole /Volume

Molarity = 3.75 / 3.36

Molarity = 1.12 mol/L

Thus, the molarity of the solution is 1.12 mol/L

Explanation:

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Answer:

answer is A. Endocrine system

Endocrine glands secrete hormones straight into the bloodstream. Hormones help to control many body functions, such as growth, repair and reproduction.

Answer:

A endocrine system

this is the answer

Answer: Uranium enrichment. Uranium is used to fuel nuclear reactors; however, uranium must be enriched before it can be used as fuel. Enriching uranium increases the amount of uranium-235 (U235) that can sustain the nuclear reaction needed to release energy and produce electricity at a nuclear power plant.

Answer:

See explanation and image attached

Explanation:

Aromatic compounds undergo electrophilic aromatic substitution reactions in which the aromatic ring is maintained.

Substituted benzenes may be more or less reactive towards electrophilic aromatic substitution than benzene depending on the nature of the substituent present in the ring.

Substituents that activate the ring towards electrophilic substitution such as -OCH3 are ortho-para directing.

The major products of the bromination of anisole are p-bromoanisole and o-bromoanisole. The resonance structures leading to these products are shown in the image attached.

Answer:

dissolution is the process

An isotope is an element with the same atomic number but different mass number due to differences in number of neutrons.

electron configuration is 2,8,6.

Belongs to group 6 and period group 3.

It forms an ion by accepting 2 electrons

Answer: The layers are ordered by density, with the least dense layer on top, and the densest layer on the bottom.

Explanation:

Plato

Fats may be either saturated or unsaturated. A saturated fat is a fat that consists of triglycerides whose carbon chains consist entirely of carbon-carbon single bonds. ... An unsaturated fat is a fat that consists of triglycerides whose carbon chains contain one or more carbon-carbon double bonds.

Solution :

A Grignard compound or a Grignard reagent is defined as a chemical compound having a generic formula of  R−Mg−X.

Here, X = halogen

          R = organic group

The Grignard reagents are obtained by treating the organic halide  with a magnesium metal.

In the context, when  trans-1-bromo-1-butene is reacted with magnesium, a Grignard reagent is produced.

When this Grignard reagent is reacted with an ethanol, the following product is obtained in the attachment :