Complete the following table. The first row has been completed as an example.
Symbol
Atomic number Mass number Number of protons Number of neutrons
17C1
17
37
17
20
238
U
92
92
238
146
92
325
16
32
16
16
5 Fe
54
26
I
19
1.K
41
22
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The sample that uses the substance that Jacob and Natalie should use to make a cold pack that will do the best job of keeping food cool is sample 2, because it absorbs the most energy (option B).

Endothermic refers to a chemical reaction that absorbs heat energy from its surroundings. This ensures that the temperature of the surroundings is cool or has a lower temperature.

According to this question, Jacob and Natalie are asked by their science teacher to design a warming or cooling device. They make use of certain substances, however, sample 2 has the lowest final temperature of -4°C.

This shows that sample 2 absorbs the most energy, hence, would be the best for keeping the food cool.

The incomplete question is as follows:

Jacob and Natalie are asked by their science teacher to design a warming or cooling device. They decide to design a cold pack that can be used to help keep food cool. Jacob and Natalie read about different substances that can be used inside cold packs and learn that most cold packs use endothermic reactions to cool objects.

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The mass (in grams) of sodium carbonate, Na₂CO₃ required to produce 85 grams of barium carbonate, BaCO₃ is 45.7 grams

First, we shall observe the balanced equation to obtain useful information. This is shown below:

Na₂CO₃ + BaSO₄ -> BaCO₃ + Na₂SO₄

From the balanced equation above,

197 g of BaCO₃ were obtained from 106 g of Na₂CO₃

With the above information, we can obtain the mass of sodium carbonate, Na₂CO₃ required to produce 85 grams of barium carbonate, BaCO₃. This is illustrated below:

From the balanced equation above,

197 g of BaCO₃ were obtained from 106 g of Na₂CO₃

Therefore,

85 g of BaCO₃ will be obtain from = (85 × 106) / 197 = 45.7 g of Na₂CO₃

Thus, we can conclude from the above calculation that the mass of sodium carbonate, Na₂CO₃ required is 45.7 grams

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Answer: 78.59 lb/ft

Explanation:

use stoichiometry to solve

1.26g/cm x ( 1pound/ 454 grams) X (28317 Cm/1 ft) =  78.59 pounds/ft

The number that is the same as the exponentiation given as follows: 2.5 × 10-³ is 0.0025.

Exponentiation is the process of calculating a power by multiplying together a number of equal factors, where the exponent specifies the number of factors to multiply.

For example, if 10 is multiplied three times, then it can be written as "10 raised to 3" which means 10³. In this case, 10 is the base, and 3 is the exponent.

Therefore, a number 0.0025 can be written in exponentiation as 2.5 × 10-³ by counting the number of zeros forward.

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4) The volume of the HCl used is 9.500 mL while the volume of the NaOH used is 3.800 mL.

5) Molarity of sodium hydroxide is obtained from; Molarity of HCl * 1/2

By reacting an unknown component with a known quantity of a different chemical known as a titrant, titration is a laboratory procedure used to measure the concentration of an unknown substance, often a solute dissolved in a liquid.

The endpoint of a titration can be detected in a number of ways, depending on the specific titration being performed.

4)

Volume of the Acid used = Initial reading - Final reading = 25.00 - 15.50 = 9.500 mL

Volume of the base used = 8.80 - 5.00 = 3.800 mL

5)

We know that the mole ratio is 1:2 and the implication of this is that the set up to obtain the molarity of the sodium hydroxide solution is Molarity of HCl * 1/2

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We need 25.5 g of KCl and 274.5 g of water to make 300. g of 8.50% KCl solution.

To find the masses of potassium chloride (KCl) and water needed, we need to use the concentration of the solution and the total mass of the solution.

We need to find the mass of KCl in the solution. We know that the solution is 8.50% KCl by mass, so:

mass of KCl = 8.50% x 300. g = 25.5 g

We can find the mass of water in the solution by subtracting the mass of KCl from the total mass of the solution:

mass of water = 300. g - 25.5 g = 274.5 g

To create 300 g of 8.50% KCl solution, we need 25.5 g of KCl and 274.5 g of water.

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The formula for the activation energy was used to obtain;

a. The result is -2.11 * 10^-4 K

b. The result is  -3.29

The bare minimum of energy required to start a chemical reaction is referred to as activation energy. For a reaction to move from the reactants to the products, the energy barrier must be broken.

To break existing bonds and generate new ones, reactant molecules must collide with enough force and in the proper direction during a chemical reaction. The energy needed to dissolve these bonds and start the atoms moving around to generate the products is known as the activation energy.

We know that we can use the formula;

1/T2 - 1/T1

= 1/318 - 1/298

= -2.11 * 10^-4 K

Again;

ln(k1/k2) = ln(0.1/2.70)

= -3.29

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One liquid substance that could be used in the laboratory for dissolving dry mortar on floor tiles is hydrochloric acid (HCl). Hydrochloric acid is a strong acid commonly used in laboratories for various purposes, including cleaning and dissolving mineral deposits.

When dry mortar, which is primarily composed of cement, hardens on floor tiles, it can be challenging to remove using traditional cleaning methods. However, hydrochloric acid can effectively dissolve and break down the cementitious components of the mortar.

It is important to note that when using hydrochloric acid, proper safety precautions should be followed, such as wearing protective gloves, goggles, and working in a well-ventilated area.

Additionally, it is crucial to dilute the hydrochloric acid to an appropriate concentration for the specific task, as using it undiluted can cause damage to the tiles or other surfaces.

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To prepare 70 mL of zinc sulfate eyedrops APF, you would need the following ingredients:

Zinc sulfate monohydrate: 0.07 g

Chlorobutol aqueous solution: 10.45 mL

Boric acid powder: 0.7 g

Glycol aqueous solution: 0.14 mL

To calculate the amount of each ingredient needed to prepare 70 mL of zinc sulfate eye drops APF, we'll follow these steps:

Step 1: Determine the concentration of zinc sulfate needed. Since the recipe doesn't specify the concentration, we'll assume a standard concentration of 0.1% w/v.

Step 2: Calculate the amount of zinc sulfate required. The desired concentration is 0.1% w/v, and we need to prepare 70 mL of the eye drops. Therefore, the amount of zinc sulfate needed can be calculated as follows:

Amount of zinc sulfate (g) = (Desired concentration (g/100 mL) * Volume (mL))/100

                       = (0.1 * 70)/100

                       = 0.07 g

Step 3: Determine the amounts of other ingredients based on the provided ratios. The chlorobutol solution is at a concentration of 0.67% w/v, so we need to calculate the volume required using the ratio:

Volume of chlorobutol solution (mL) = (Amount of zinc sulfate (g) * 100)/Concentration of chlorobutol (%)

                                  = (0.07 * 100)/0.67

                                  = 10.45 mL

The boric acid powder doesn't specify the concentration, so we'll assume it to be 1% w/v. Using the same logic, we can calculate the amount of boric acid powder required:

Amount of boric acid powder (g) = (Desired concentration (g/100 mL) * Volume (mL))/100

                             = (1 * 70)/100

                             = 0.7 g

Finally, the glycol solution is at a concentration of 50% w/v, so the volume required can be calculated as:

Volume of glycol solution (mL) = (Amount of zinc sulfate (g) * 100)/Concentration of glycol (%)

                            = (0.07 * 100)/50

                            = 0.14 mL

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Answer:

C. polar nature

Explanation:

The polarity of water and its ability to hydrogen bonding contributes to it's unique properties

You can determine  the number of electrons it has in the highest occupied energy level. Option A

Representative elements are found in Groups 1, 2, and 13-18 of the periodic table. The group number corresponds to the number of valence electrons, which are the electrons in the outermost energy level.

For example, elements in Group 1 have one valence electron, while elements in Group 18 have eight valence electrons (except helium, which has two). Knowing the group number helps predict the element's chemical properties, as valence electrons play a significant role in chemical reactions and bonding.

Information regarding the total number of electrons (B), the number of filled energy levels (C), and the number of protons and neutrons in the nucleus (D) cannot be determined from just the group number.

However, you can use the element's atomic number and electron configuration to find this information. The atomic number represents the total number of protons and electrons in an atom, while electron configuration illustrates the distribution of electrons in energy levels. Option A

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Answer: the temperature would increase

Explanation:

because if one spot on the earth got the same amount of light through the summer and winter it would have a severe amount of drought and nothing to cool it down since all off it evaperated

Answer:

Explanation:

NH4I  NH4 is ammonium thus a base.  All other bases end with OH except ammonia which is NH3

Answer:

What is meant by activated complex?

The state of the particles that is in between the reactants and products is called the activated complex. An activated complex is an unstable arrangement of atoms that exists momentarily at the peak of the activation energy barrier.

source:Gogle

(a) Element C (2,8,8) is unlikely to react with the others.

(b) Elements D (2,8,7) and E (2,8,3) will likely react to form covalent compounds.

(c) Elements A (2,8,2) and B (2,8,6) will likely react to form ionic solids.

(a) It has a complete outer electron shell (valence shell) with eight electrons, fulfilling the octet rule. This stable configuration makes element C less likely to undergo chemical reactions and form compounds.

(b) Covalent compounds involve the sharing of electrons between atoms, typically nonmetals. Both D and E have incomplete outer electron shells and can form covalent bonds by sharing electrons with other elements.

(c) Ionic compounds involve the transfer of electrons from one atom to another, typically between metals and nonmetals. When A and B form ionic solids, they will achieve a stable electron configuration by losing or gaining electrons, respectively.

Element A would lose two electrons to achieve a stable configuration, resulting in a valency of +2. Element B would gain two electrons, resulting in a valency of -2.

The weakest bond among ionic, covalent, and hydrogen bonds is the hydrogen bond. Hydrogen bonds are relatively weaker than ionic and covalent bonds. They occur when a hydrogen atom with a partial positive charge interacts with an electronegative atom, such as oxygen or nitrogen, with a partial negative charge.

Hydrogen bonds are important in various biological and chemical processes, but they are weaker compared to the strong bonds formed in ionic and covalent compounds.

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The mass of the vinegar the student put in the flask at first is 18 grams.

To find the mass of the vinegar, you have to consider the law of conservation of mass.

Ths law says that the total mass of the reactants before a chemical reaction is equal to the total mass of the products after the reaction.

Therefore

Mass of vinegar = Total mass after reaction - (mass of flask + mass of balloon with baking soda)

= 125 grams - (100 grams + 7 grams)

= 18 grams

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The steps are;

Determine the titration reaction equation

Perform the titration

Record the data

Calculate the concentration

Find the chemical equation for the reaction that takes place during the titration.

Swirl or stir the analyte solution continually as you gradually add the titrant from the burette. An indication may be used to pinpoint the reaction's endpoint once the titrant and analyte react.

To calculate the amount of titrant utilized in the reaction, take note of the initial and final burette readings.  To calculate the ratio between the titrant and the analyte, use the stoichiometry of the balanced chemical equation.

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The approximate mass of CO2 dissolved in the alcoholic drink is 832.5 grams.

To calculate the approximate mass of CO2 dissolved in the alcoholic drink, we need to consider the mole fraction of water and the composition of the solution.First, let's determine the number of moles of water and ethanol in the solution:

Molar mass of H2O = 18.02 g/mol

Number of moles of H2O = mass of H2O / molar mass of H2O = 216.0 g / 18.02 g/mol = 11.994 mol

Molar mass of C2H5OH = 46.07 g/mol

Number of moles of C2H5OH = mass of C2H5OH / molar mass of C2H5OH = 9.2 g / 46.07 g/mol = 0.1998 mol

Next, we can calculate the mole fraction of ethanol:

Mole fraction of ethanol = (moles of C2H5OH) / (moles of H2O + moles of C2H5OH) = 0.1998 mol / (11.994 mol + 0.1998 mol) = 0.0164

Since the mole fraction of water is given as 0.9, we can calculate the mole fraction of CO2:

Mole fraction of CO2 = 1 - (mole fraction of water + mole fraction of ethanol) = 1 - (0.9 + 0.0164) = 0.0836

Now, we need to determine the mass of CO2 dissolved in the solution. Assuming ideal behavior, we can use Raoult's law to calculate the approximate mass of CO2:

Mass of CO2 = (mole fraction of CO2) * (molar mass of CO2) * (total mass of the solution)

           = 0.0836 * 44.01 g/mol * (216.0 g + 9.2 g)

           = 0.0836 * 44.01 g/mol * 225.2 g

           ≈ 832.5 g

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A sp² hybrid orbital on C-1 overlaps with a sp hybrid orbital on C-2 to form the sigma bond between C-1 and C-2. This statement regarding the skeletal structure of the organic molecule true. The correct option is option A.

In general, molecules containing carbon (C) are referred to as organic compounds. Carbon atoms serve as the primary structural framework for the enormous diversity of naturally occurring compounds. Organic substances play a critical role in the existence of all life forms on Earth (and perhaps elsewhere in the universe). A sp² hybrid orbital on C-1 overlaps with a sp hybrid orbital on C-2 to form the sigma bond between C-1 and C-2.

Therefore, the correct option is option A.

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Thomson's experimental evidence supports Rutherford's atomic model, as it aligns with the observed behavior of the cathode rays in the cathode ray tube experiment

Thomson's experiment, known as the cathode ray tube experiment, involved passing an electric current through a partially evacuated tube and observing the behavior of the cathode rays. Thomson discovered that the cathode rays were negatively charged particles, which later came to be known as electrons. Based on Thomson's experimental evidence, it is compatible with Rutherford's model, which proposed a dense positively charged nucleus and negatively charged electrons. Thomson's experiment indicated the presence of negatively charged particles (electrons) and their deflection towards the positively charged plate, supporting the idea of a small, dense, positively charged nucleus within the atom. In summary, Thomson's experimental evidence supports Rutherford's atomic model, as it aligns with the observed behavior of the cathode rays in the cathode ray tube experiment. The experiment provided strong evidence for the existence of negatively charged electrons within atoms and the presence of a small, dense, positively charged nucleus.

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The pH of the solution with a [H₃O⁺] concentration of 3.5 * 10^(-3) mol/L is approximately 2.456.

To determine the pH of a solution based on the concentration of H₃O⁺, you can use the equation:

pH = -log[H₃O⁺]

Given that [H₃O⁺] = 3.5 * 10^(-3) mol/L, we can substitute this value into the equation:

pH = -log(3.5 * 10^(-3))

To evaluate this using a calculator or math software:

pH ≈ -log(3.5 * 10^(-3)) ≈ -(-2.456) ≈ 2.456

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The scientist who wrote the Book of Optics is In al-Haytham.

option B.

The Book of Optics presented experimentally founded arguments against the widely held extramission theory of vision (as held by Euclid in his Optica), and proposed the modern intromission theory, the now accepted model that vision takes place by light entering the eye.

The Book of Optics is a seven-volume treatise on optics and other fields of study composed by the medieval Arab scholar Ibn al-Haytham, known in the West as Alhazen or Alhacen.

Thus, the scientist who wrote the Book of Optics is In al-Haytham.

Other options such as Warren Washington, Christian Doppler and Galileo Galilei are not correct.

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Mescaline produces a wide range of psychoactive effects when ingested, including altered perception of reality, hallucinations, and euphoria. It is a powerful psychedelic drug that has been used for centuries by Native American tribes in spiritual ceremonies

Mescaline is a hallucinogenic alkaloid that is derived from the Peyote cactus. Mescaline is a complex organic molecule that can be synthesized in the laboratory from 3,4,5-trimethoxybenzyl bromide in two steps.The first step involves nucleophilic substitution using sodium cyanide, and the second step is a reduction using lithium aluminum hydride (LAH).Here's how mescaline can be synthesized from 3,4,5-trimethoxybenzyl bromide:Step 1: Nucleophilic substitution using sodium cyanideThe reaction of 3,4,5-trimethoxybenzyl bromide with sodium cyanide results in the formation of the nitrile derivative. NaCN serves as the nucleophile in this reaction, and it replaces the bromide ion.The mechanism for this reaction involves the following steps: A nucleophilic attack by the cyanide ion on the benzyl bromide. The carbon-bromine bond breaks, and the benzyl cation is formed. A second nucleophilic attack by the cyanide ion occurs on the benzyl cation, resulting in the formation of the nitrile derivative.Here's the reaction equation for this step:Step 2: Reduction using lithium aluminum hydrideThe next step is the reduction of the nitrile derivative using LAH. LAH serves as a strong reducing agent in this reaction and reduces the nitrile derivative to the amine. The mechanism for this reaction involves the following steps: A nucleophilic attack by LAH on the nitrile derivative. This results in the formation of an imine intermediate. The imine intermediate reacts with another LAH molecule, resulting in the formation of the amine.Here's the reaction equation for this step:Mescaline structure: Mescaline is a psychoactive compound that belongs to the phenethylamine class of alkaloids. The structure of mescaline is as follows: The molecule has three methoxy groups attached to the benzene ring, and it has an amine functional group. The molecule is a white crystalline powder that is soluble in water and alcohol.

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Alleles and traits related as D. Alleles are distinct versions of genes, and they code for traits, which are distinct forms of characteristics.

Alleles and traits are closely related in terms of genetics and inheritance. Alleles are alternative forms of a gene that occupy the same locus on a chromosome. They represent different variations of a specific gene. Traits, on the other hand, are the observable characteristics or features of an organism that are determined by the combination of alleles.

Each individual inherits two alleles for a particular gene, one from each parent. These alleles can be the same (homozygous) or different (heterozygous). The combination of alleles determines the expression of traits in an organism. For example, in the case of eye color, the gene may have alleles for blue and brown eye color. An individual may inherit two blue alleles (homozygous), resulting in the trait of blue eyes, or they may inherit one blue and one brown allele (heterozygous), resulting in the trait of brown eyes. In summary, alleles are distinct versions of genes, and they code for the different variations of traits or characteristics that are observed in organisms. The correct answer is D. Alleles are distinct versions of genes, and they code for traits, which are distinct forms of characteristics.

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Answer:

LiOH is soluble. Na2CO3 is soluble. Cu(OH)2 is insoluble.

Explanation:

LiOH is soluble. Na2CO3 is soluble. Cu(OH)2 is insoluble.

The type of aluminum the students should plan to use in order to increase the reaction rate is powder because the greater surface area will allow more collisions between reactants to occur.

The correct option is A.

The nature of the surface area of the reactants will either decrease or increase the rate of reaction.

An increased surface area of the reactants will increase the rate of a reaction because the greater surface area will allow more collisions between reactants to occur.

A decrease in the surface area of the reactants will decrease the rate of a reaction because the greater surface area will not allow more collisions between reactants to occur.

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To calculate the molarity of the sodium hydroxide (NaOH) solution, we need to perform a titration with a standardized solution of hydrochloric acid (HCl). Here is the numerical setup for calculating the molarity of the NaOH solution:

Measure the volume of the HCl solution used in the titration. Let's say you used 25.0 mL of 0.100 M HCl.

Calculate the number of moles of HCl used in the titration: moles of HCl = M x V = 0.100 mol/L x 0.0250 L = 0.00250 mol.

Use the balanced chemical equation for the reaction between HCl and NaOH to determine the number of moles of NaOH that reacted with the HCl. The balanced chemical equation is:

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)

Since the stoichiometry of the reaction is 1:1 between HCl and NaOH, the number of moles of NaOH that reacted is also 0.00250 mol.

4. Determine the volume of NaOH used in the titration. Let's say you used 30.0 mL of NaOH solution.

Calculate the molarity of the NaOH solution: Molarity of NaOH = moles of NaOH / volume of NaOH solution (in L) = 0.00250 mol / 0.0300 L = 0.0833 mol/L.

To determine the total volume of HCl(aq) and NaOH(aq) used in the titration, simply add together the volumes of HCl and NaOH that were used. In this example, the total volume would be 25.0 mL + 30.0 mL = 55.0 mL.

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The pH scale determines how acidic or basic water is. The range is 0 to 14, with 7 representing neutrality.

Thus, Acidity is indicated by pH values below 7, whereas baseness is shown by pH values above 7. In reality, pH is a measurement of the proportion of free hydrogen and hydroxyl ions in water.

While water with more free hydroxyl ions is basic, water with more free hydrogen ions is acidic. Since chemicals in the water can change pH, pH is a crucial sign that the chemical composition of the water is changing. "Logarithmic units" are used to report pH.

Each number corresponds to a 10-fold difference in the water's acidity or basicity. Ten times more acidic than water is water is water with a pH of five.

The pH scale determines how basic or acidic a substance is. We consume a variety of drinks with varying pH levels during our daily lives. A neutral material is water. The acidity of soda and coffee varies.

Thus, The pH scale determines how acidic or basic water is. The range is 0 to 14, with 7 representing neutrality.

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Answer:

hey are the results of many experiments over a long period of time.

Explanation: