Q: What type of evidence would you use to identify a chemical change?

Answer:

The defect of vision suffered by the person is Myopia

Explanation:

The person can't see farther objects but is able to read a book which is placed closely to the eyes, using these observations the person is suffering from MYOPIA(nearsightedness) in which observer see close objects clearly but farther objects appear blurred.

The light entering the eye isn't correctly bent, the eyeball becomes big , or the eye lens become too converging, which converges the light ray in front of the cornea

This defect can be cured by using concave lenses.

The authors of the research paper "Molecular Anatomy of a Trafficking Organelle" (Cell, 2006, Vol. 127; 831–846) chose to examine synaptic vesicles due to their crucial role in neuronal communication and synaptic transmission.

Synaptic vesicles are specialized organelles found in neurons that store and release neurotransmitters, which are essential for transmitting signals between nerve cells. They play a vital role in synaptic transmission, a fundamental process underlying brain function. The authors likely chose to focus on synaptic vesicles because understanding their molecular anatomy and trafficking mechanisms is crucial for unraveling the intricate processes involved in neuronal communication.

By studying synaptic vesicles, researchers can gain insights into how these vesicles are formed, transported, and targeted to specific regions within neurons. Investigating the molecular components and mechanisms involved in synaptic vesicle trafficking can provide valuable knowledge about neuronal function, synaptic plasticity, and neurotransmission. Furthermore, studying synaptic vesicles can contribute to our understanding of various neurological disorders associated with synaptic dysfunction, such as Alzheimer's disease, Parkinson's disease, and epilepsy. Therefore, the choice to examine synaptic vesicles in this research paper was likely driven by their significance in neuronal physiology and their potential implications for understanding and treating neurological disorders.

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Explanation:

H2O:

2 H2O shows 2 atoms of hydrogen. The number 2 in front of it means 2 moles of H2O

----------

CHA:

It only shows 1 atom of hydrogen

1 CHA means 1 mole of CHA

2 CHA means 2 moles of CHA

----------

HO2:

It only shows 1 atom of hydrogen

---------

H2SO4:

It shows 2 atoms of hydrogen

Answer:

H2O

H2SO4

Answer:

550 K

Explanation:

Given the following data;

Original Volume, V1 = 20mL

Original Temperature, T1 = 200K

New Temperature, V2 = 55mL

To find new temperature T2, we would use Charles' law.

Charles states that when the pressure of an ideal gas is kept constant, the volume of the gas is directly proportional to the absolute temperature of the gas.

Mathematically, Charles is given by;

\( VT = K\)

\( \frac{V1}{T1} = \frac{V2}{T2}\)

Making T2 the subject of formula, we have;

\(T_{2} = \frac{V2}{V1} * T_{1}\\\)

Substituting into the equation;

\(T_{2} = \frac{55}{20} * 200\\T_{2} = \frac{11000}{20}\\T_{2} = 550K\)

Therefore, the new temperature is 550K.

Answer:

Explanation:

Solubility of KNO₃ at 20° C = 32 g / 100g of water

that means , per 100 g of water maximum of 32 g of  KNO₃ can be dissolved at 20° C .

Solubility of KNO₃ at 40° C = 62 g / 100g of water

that means , per 100 g of water maximum of 62 g of  KNO₃ can be dissolved

40° C.

So when a saturated solution in which maximum KNO₃ has been dissolved is cooled from  40° C to 20° C , due to decrease in solubility at lower temperature some KNO₃ will come out of the solution . Per 100 gram of saturated solution , 62 - 32 = 30 g of KNO₃ will precipitate out or come out of water . They can be filtered out .

Therefore, the enthalpy change for CuCl₂(s)→ Cu(s) + Cl₂(g) is 66Kj.

From the equation given below we can get the enthalpy change.

CuCl₂(s)→ Cu(s) + Cl₂(g)ΔΗ = 206 kJ

2Cu(s) + Cl₂(g) → 2CuCl(s)ΔH = -136

We can add the two target species together, then cancel the cu and cl2

Cu +Cl=Cucl2

If we reverse the equation we will get.

Cu +Cl2 =Cucl2 ΔΗ - 206 kJ

2CuCl(s) +   Cu(s)= cu +Cl + 2CuCl(s)

ΔH =-(ΔH1+2ΔH2) = -206 +2(-136)

=66kj

Therefore, the enthalpy change for CuCl₂(s)→ Cu(s) + Cl₂(g) is 66Kj.

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Answer:

it's A) or E)

others are not suitable cuz their melting point is weak.

Answer:

Gallium

Explanation:

Because the melting point is low and the drinks are usually around 60-70 degrees Celsius so it wil melt

The synthetic organic chemist who successfully synthesized physostigmine was Robert Burns Woodward.

He was an American organic chemist who is considered by many to be the preeminent organic chemist of the twentieth century. Woodward's synthesis of physostigmine, an alkaloid found in the Calabar bean, was an important milestone in modern organic chemistry. Physostigmine works by obstructing acetylcholine metabolism. The enzyme that breaks down acetylcholine in the synaptic cleft of the neuromuscular junction, acetylcholinesterase, is inhibited in a reversible manner by this substance.Woodward's method of synthesizing physostigmine was the first successful total synthesis of a complex natural product, and it established the precedent for modern organic synthesis.

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Answer: The iron equilibrium is the more positive, and so will go in the forward direction. The tin equilibrium is less positive (more negative), and will be driven backwards. So the tin(II) ions will reduce iron(III) ions to iron(II) ions. In the process, of course, the tin(II) ions will be oxidised to tin(IV) ions.

Explanation:

Answer:

\(\huge\boxed{\sf 1.51\ L}\)

Explanation:

From the reaction:

2 moles of Na produce 1 mole of H₂

Converting 3.10 g of Na into moles:

Moles = mass / molar mass

= 3.10 / 23

= 0.135 mol

From the reaction:

2 Na = 1 H₂

1 Na = 1/2 H₂

1 Na = 0.5 H₂

1 mol of Na = 0.5 mol of H₂

0.135 mol of Na = 0.5 × 0.135 mol of H₂

0.135 mol of Na = 0.067 mol of H₂

So, 0.135 mol of Na (3.10 g) produce 0.067 mol of H₂

Convert 0.067 mol of H₂ into L:

= mol × molar value

[molar value = 22.4 L/mol]

= 0.067 × 22.4

= 1.51 L

\(\rule[225]{225}{2}\)

Addition of HCl and KOH decreases the concentration of HF and H₃O⁺, but increases the concentration of F⁻. Addition of KF and HF decreases the concentration of HF, but increases the concentration of F⁻ and H₃O⁺. Addition of NaCl does not affect the concentrations of HF, H₃O⁺, and F⁻

The concentration of HF will decrease due to the reaction with HCl to form H₂O and FCl. The concentration of H₃O⁺ and F⁻ will increase due to the dissociation of HCl and the ionization of HF.

The concentration of HF will decrease due to the reaction with KF to form KHF₂. The concentration of H₃O⁺ will decrease due to the consumption of H⁺ ions by F⁻, and the concentration of F⁻ will increase due to the dissociation of KF.

The concentration of HF, H₃O⁺, and F⁻ will remain unchanged since NaCl is a neutral salt that does not react with HF.

The concentration of HF will decrease due to the reaction with KOH to form H₂O and KF. The concentration of H₃O⁺ will decrease due to the consumption of H⁺ ions by OH⁻, and the concentration of F⁻ will increase due to the dissociation of KF.

The concentration of HF will increase since it is being added to the solution. The concentration of H₃O⁺ and F⁻ will also increase due to the ionization of HF.

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--The complete question is, What is the effect on the concentration of hydrofluoric acid, hydronium ion, and fluoride ion when the following are added to separate solutions of hydrofluoric acid? HCl, KF, NaCl, KOH and HF--

The correct answer is (d) They are broken down when exposed to heat and oxygen.

The minerals are inorganic substances which are obtained from earth's crust. It is a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties.

Common minerals include quartz, feldspar, mica, amphibole, olivine, and calcite. They are used by plants and animals to perform various physiological functions. Plants obtain minerals from the soil. Animals get minerals from plants or other animals.

Therefore, options (a), (b), and (c) are correct because minerals are not produced by plants and animals. Minerals are in their simplest chemical form, and minerals are obtained from the earth's crust and environment. They are not broken down when exposed to heat and oxygen. So, option (d) is incorrect. Hence, the correct option is (d) They are broken down when exposed to heat and oxygen.

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When sodium carbonate is added to hydrochloric acid, a chemical reaction occurs that produces salt, carbon dioxide, and water as products.

The reaction is represented by the equation:

Na₂CO₃ + 2HCl → 2NaCl + CO₂ + H₂O.

Sodium carbonate (Na₂CO₃) and hydrochloric acid (HCl) are both strong electrolytes, and their reaction is a type of double displacement reaction.

Upon adding sodium carbonate to hydrochloric acid, a fizzing sound and bubbling of gas will be observed. This indicates that carbon dioxide is being produced as one of the products. The salt produced as a product of the reaction is sodium chloride (NaCl), which is a white solid.

The reaction is highly exothermic, which means it releases heat. This can also be observed by touching the beaker or container holding the reaction mixture, which will feel warm or hot to the touch.

In conclusion, upon adding sodium carbonate to hydrochloric acid, the reaction produces salt, carbon dioxide, and water as products, accompanied by fizzing, bubbling of gas, and the release of heat.

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Answer:

See explanation

Explanation:

When dealing with the Electromagnetic Spectrum, one should remember the acronym ROYGBIV. This will apply to visible spectrum but the non-visible spectra can de logically deduced from the sequence. That is ...

   R-Red > O-Orange > Y-Yellow > G-Green > B-Blue > I-Indigo > V-Violet

In relation to the three wave properties; wavelength (λ), frequency (ν) & energy (ΔE) ...

Wavelengths => Long λ                                                                       Short λ

Frequency     => Low  ν                                                                       High ν

Energy           => Low  ΔE                                                                    High ΔE  

Note that all 'L's' are on the 'Left'

On Left => Long wavelengths, Low frequency & Low energy; the 'opposites' are on 'the other end of the list'.

Therefore for other wavelengths outside the visible spectrum set up as follows, start with visible spectrum in the middle and insert the invisible spectra of interest.

                          Long λ <= Visible (R.0.Y.G.B.I.V.) => Short λ

 λ (cm):    10¹            10⁻²          10⁻³  (10⁻⁵- 10⁻⁶)    10⁻⁷       10⁻⁹    (10⁻¹¹ - 10⁻¹³)            

             [radio > microwave > IR   >   visible   >  UV  >  X-Rays > Gamma]

Hope this helps :-)

Answer:

Weight = Mass * Gravity = 50 kg * 10.5m/s² = 525 N

Explanation:

Answer:

See note in Explanation

Explanation:

The modern periodic table of the elements is arranged in order of increasing atomic numbers which is also in terms of the number of protons in the nucleus. That is, for any element listed on the periodic table its atomic number equals the number of protons in the nucleus. Thus, the element with 2 protons in its nucleus would be element #2 (Helium), element #3 (Lithium) has 3 protons in its nucleus and element #4 (Beryllium) has an atomic number 4 and contains 4 protons in its nucleus.

Also, this arrangement of elements finds that elements below elements 2, 3 & 4, Neon #10; sodium #11 & magnesium #12 have similar chemical and physical properties as does elements #2, #3 & #4. Such gives rise to the 'Periodic Law' => the chemical and physical properties of the elements is a periodic function of their atomic number (or, number of protons in the nucleus).

Answer:

1. F, H, E

2. A, D, I

3. G

4. E, B, H

5. C

Explanation:

Answer:

If Black Holes Are "Black," How Do Scientists Know They Are There? A black hole can not be seen because strong gravity pulls all of the light into the middle of the black hole. But scientists can see how the strong gravity affects the stars and gas around the black hole.

Explanation:

some examples; 1. Pushing a wheel barrow.

2. Opening or closing a door.

3. Squeezing wet clothes.

4. Gravitational force.

5. Brakes applied to stop a moving vehicle.

6. A football kicked harder that decreases due to the frictional force.

7. Rubbing a glass rod with a silk.

8. Pressure applied on a pin of a notice board.

9. Running

10. Pushing

Supernova or void is another force or phenomenon that cannot be seen directly similar to black holes.Examples of the effects are gravitational force, brakes applied to stop a moving vehicle.

Force is defined as a cause which is capable of changing the motion of an object. It can cause an object which has mass to change it's velocity. It is also simply a push or a pull . It has both magnitude as well as direction.Hence, it is a vector quantity.

It has SI units of Newton and is represented by'F'.Newton's second law states that force which acts on an object is equal to momentum which changes with time. If mass of object is constant, acceleration is directly proportional to net force acting on an object.

The concepts which related to force are thrust and torque .Thrust increases the velocity of an object and torque produces change in rotational speed of an object.

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Answer:

the air will escape from the jar

Explanation:

Due to its low density air in the jar will be displaced and be replaced by water.

The statement "Most hardness tests involve pressing a hard object into the surface of a test specimen and measuring the resulting indentation or its effect" is true because the majority of the hardness tests depend on measuring the resulting indentation or the effect of the hard object on the test specimen.

Hardness testing is a method of measuring how well a material can resist permanent indentation or scratch by another material. This method is used to evaluate the toughness of materials like metals, plastics, ceramics, and polymers.

A variety of methods is available for testing hardness, which is divided into two types based on the method of testing; Dynamic Hardness Testing and Static Hardness Testing..

The sample of Dynamic Hardness Testing is exposed to a sudden load and the indentations left are analyzed. In Static Hardness Testing, an object is applied to the sample and the pressure required to deform the material is measured.

The Rockwell test, the Brinell test, the Vickers test, and the Knoop test are the most widely used hardness tests. The Brinell hardness test, which is based on the principle of measuring the diameter of the impression left on the specimen when an object is pressed into it, is the most common method of testing industrial materials.

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The mass of \(Al_{2} S_{3}\) produced is 15.616 grams.

The reaction taking place is as follows:

\(2Al+ 3S\) →\(Al_{2} S_{3} (s)\)

Moles of Al = mass/molar mass = 10.0g/27.0g/mol

= 0.370 mol

Moles of S = mass/molar mass = 15.0g/(32.065g/mol)

= 0.468 mol

Al and S reacts in the molar ratio of 2:3.

2 moles of Al reacts with 3 moles of S

0.370 moles of Al will react with S = (3/2)*0.370mol

= 0.555 mol

Similarly, 0.468 moles of S will react with Al = 2/3 *0.468mol

= 0.312 mol

Thus, Al is in excess and S is the limiting reactant (some of Al will be left over ,S will completely react)

So, moles of \(Al_{2} S_{3}\) produced=1/3*0.312 mol of S

= 0.104 mol

Mass of \(Al_{2} S_{3}\) produced = moles*molar mass of \(Al_{2} S_{3}\)

= 0.104mol*150.158g/mol

= 15.616 grams

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The molar mass of the gas, given that 3.25 g of the gas occupied 2.56 L is 30.66g/mol

To obtain the molar mass of the gas, we shall first obtain the number of mole of the gas. This can be obtained as follow:

PV = nRT

0.95 × 2.56 = n × 0.0821 × 280

Divide both sides by (0.0821 × 280)

n = (0.95 × 2.56) / (0.0821 × 280)

n = 0.106 mole

Haven obtain the mole of the gas, we shall determine the molar mass of the gas as follow:

Molar mass = mass / mole

Molar mass of gas = 3.25 / 0.106

Molar mass of gas = 30.66g/mol

Thus, the molar mass of the gas is 30.66g/mol

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Answer:

because its yellow

Explanation:

because rats like yellow

Answer:

option d. 56/26 Fe is the correct answer.

Solute

The salt being dissolved is the solute.

Answer:

a.

Na2CO3 (aq) + 2 HCl (aq) → H2O (l) + CO2 (g) + 2 NaCl (aq)

b.

0.0783 mols of HCl

Explanation:

Na2CO3 (aq) + 2 HCl (aq) → H2O (l) + CO2 (g) + 2 NaCl (aq)

n= 1 n= 2

Mr = 106 Mr= 36.5

m= 106g m= 73g

106 g Na2CO3 reacts with 73 g HCl

1 g Na2CO3 will react with 73/106 g HCl

4.15 g Na2CO3 will react with (73/106)× 4.15 = 2.858 g HCl

number of moles = mass/ Mr

num of moles of HCL = 2.858/36.5

= 0.07830188678

= 0.0783 mols

a. Balanced equation with state symbols:

Solid sodium carbonate (Na₂CO₃(s)) + Aqueous hydrochloric acid (2HCl(aq)) = Aqueous sodium chloride (2NaCl(aq)) + Carbon dioxide (CO₂(g)) + Water (H₂O(l))

b. 0.05 moles of HCl is required to react with 4.15 g of sodium carbonate.

To calculate the number of moles of hydrochloric acid (HCl) required to react with 4.15 g of sodium carbonate (Na₂CO₃), we first need to determine the molar mass of Na₂CO₃.

Molar mass of Na₂CO₃:

2(Na) + 1(C) + 3(O) = 2(23.0 g/mol) + 12.0 g/mol + 3(16.0 g/mol) = 46.0 g/mol + 12.0 g/mol + 48.0 g/mol = 106.0 g/mol

Next, we can use the given mass and molar mass to calculate the number of moles of Na₂CO₃:

Number of moles = Mass / Molar mass

Number of moles = 4.15 g / 106.0 g/mol ≈ 0.0391 moles

According to the balanced equation, 1 mole of Na₂CO₃ reacts with 2 moles of HCl. Therefore, the number of moles of HCl required to react with 0.0391 moles of Na₂CO₃ is:

Number of moles of HCl = 2 × 0.0391 moles ≈ 0.0782 moles

Thus, 0.0782 moles of HCl (or approximately 0.05 moles when rounded to two decimal places) are required to react exactly with 4.15 g of sodium carbonate.

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Answer:

The pH scale measures acidity of a substance. known as potential of hydrogen, it varies from 0 to 14 with 7 being the pH value of a neutral solution. Below 7 shows the substance is acidic in nature and above 7 is alkaline in nature. pH 0-3 are considered strong acids while pH 4-6 are weak acids. pH 8-10 are weak alkalines and pH 11-14 are strong alkalines. This is a general trend and there may be exeptions especially if the substance has a negative pH. However, it would not be covered likely unless you are doing university chemistry.

Answer:

Liquid

Explanation: