1. What is TRUE about hair samples from a human body?
Hair morphology stays the same as an individual gets older.
O
Every hair taken from the same scalp has matching physical characteristics.
O
Physical properties can be used to most accurately individualize hair.
Hair samples can be different even when taken from the same person.

The mass of oxygen reacted with magnesium is 8 grams.

The formula mass of a substance is defined as the sum of the atomic masses of constituent atoms that are present  in a compound. This is generally used for compounds which do not contain discrete molecules, and  ions as their constituent units.

The combustion reaction of magnesium is as follows

2Mg + 02 + heat → 2MgO

Molar mass of MgO = 24.32 g/mol

Mole of Mg in 12g = 12 ÷ 24.32 = 0.4934 mol

From the balanced reaction we can see that the mole ratio of Mg to O2 is 2:1.

Therefore for 0.4934 mol of Mg, mole of 02 required will be = 1/2 × 0.4934 = 0.2467 mol.

Molar mass of O2 = 32g/mol

Hence the mass of O2 required = 0.2467 × 32 = 7.89g

By the conservation of mass; Mg + Oxygen = MgO

Mass of Mg = 12g

Mass of MgO = 20G

Therefore the mass of oxygen reacted with Mg will be = (20-12) = 8 grams

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Answer:  The radius of atoms increases as you move down a particular group in the periodic table of elements because an atom grows larger as the number of electronic shells increases.

Explanation:

https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Physical_Properties_of_Matter/Atomic_and_Molecular_Properties/Atomic_Radii

Answer:

it is damp moist and other things

Explanation:

The moles of CO₂ that can be formed from each reactant are:

The  equation of the combustion of methane is given below as follows:

CH₄ (g) + 2 O₂ (g) ---> CO₂ (g) + 2 H₂O (g)

From the equation of the reaction, 1 mole of methane reacts with 2 moles of oxygen to produce 1 mole of carbon dioxide ad 2 moles of water.

Given that there are 2 molecules of CH₄ reacting with 5 molecules of O₂. the moles of CO₂ that can be formed from each reactant are determined from the mole ratio of the reactants and products as given in the equation of the reaction.

2 moles of methane will produce 2 moles of CO₂

5 moles of O₂ will produce 5 * 1/2 moles of CO₂ = 2.5 moles of CO₂

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Answer:

D) Compound D

Explanation:

The bond energy is the highest amount the listed bond energies and this is one of the characteristics of ionic compound because usually its involves the formation of anions and cations with the former being negative and the latter being positive.

The bond is usually strong because it is involves attraction between actions and anions. It requires transfer of electron between metals and nonmetals. The metals are usually the cations (lose electron) and nonmetals are usually the anions ( they gain electron) so when they are dissolve in water they dissociate into negative and positive ions and carries electrical charges while in solid form they are insulators example is NaCl

Answer:

Compound D

Explanation:

They are identical conformation of the same molecule.The groups which are pointed up are represented with wedge bonds and the groups which

are pointed down are represented with dash bonds.

One type of wire bonding called wedge bonds uses ultrasonic force and power to forge bonds. In the semiconductor industry, it is a well-liked and frequently applied technique. a mark that represents the location of a bond or group in relation to the paper or screen's surface. When a wedge is solid, it means that this bond or group is projecting outwards toward the observer. This bond or group is moving farther away from the viewer when the wedge is broken (hashed). A clamped piece of wire is coupled under a bonding tool (referred to as a wedge) and a bond pad during wedge bonding. A first wedge bond is created by applying pressure and ultrasonic energy for a predetermined amount of time.

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The formulas of each of the compounds are;

1) AlN

2) [tex]NH_{4} ^+[/tex]

3) [tex]C_{3} H_{8}[/tex]

The term chemical formula has to do with the representation of a compound. We know that the way that a compound is represented would help us to be able to identify the compound.

We have various compounds that have been shown in the image and we are asked to find the correct formula of the compound. We now look at the number of atoms that we have in each of the diagrams and by means of the number of atoms, we would look to see how we can be able to find the chemical formula of the compound.

By the octet rule, aluminum can combine with nitrogen to form aluminum nitride. The combination of nitrogen with four hydrogen atoms would only lead to the formation of a charged ammonium specie. A structure that contains three carbon atoms and eight hydrogen atoms can only be propane as shown.

Thus, when we see the arrangement of the atoms we now have to look at the possible compound that could be found from the arrangement shown and then write down the formula of the compound as shown.

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Thus we can see that if we leave the lid off our setup for the calibration which would allow some heat to escape to the atmosphere. This will yield a lower specific heat value

What is calibration ?

One of the fundamental methods required to ensure instrument accuracy is calibration. Calibration is the process of arranging an instrument to produce a result within an acceptable range for a sample. A major part of instrumentation design is eliminating or limiting causes that produce faulty measurements.

For today's tests, we leave the lid off our setup for calibration, allowing some heat to escape to the atmosphere. This results in a lower specific heat value.

For example, if the real value of Q before we remove the lid is 100 J, our calibration setup is 100 J.

And the metal mass is 10 g.

And the temperature has risen by 5 degrees Celsius.

Q = mcdT

Now, compute the value of C:

100 J = 10 g*C* 5C

C= 2 J / g-c

Now that the lid has been opened, some of the heat has escaped into the atmosphere,

and we have Q = 90 J.

Then;

Q = mcdT

Now, compute the value of C:

90 J = 10 g*C* 5C

C= 1.8J / g-c

Thus we can see that if we leave the lid off our setup for the calibration which would allow some heat to escape to the atmosphere. This will yield a lower specific heat value

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Considering the reaction stoichiometry, 4.3461 grams of O₂ will be consumed during the formation of 14.46 grams of Fe₂O₃.

In first place, the balanced reaction is:

4 Fe + 3 O₂  → 2 Fe₂O₃

By reaction stoichiometry (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles of each compound participate in the reaction:

The molar mass of the compounds is:

Then, by reaction stoichiometry, the following mass quantities of each compound participate in the reaction:

Mass of O₂ consumed

The following rule of three can be applied: If by reaction stoichiometry 319.4 grams of Fe₂O₃ are formed from 96 grams of O₂, 14.46 grams of Fe₂O₃ are formed from how much mass of O₂?

mass of O₂= (14.46 grams of Fe₂O₃×96 grams of O₂)÷ 319.4 grams of Fe₂O₃

mass of O₂= 4.3461 grams

Finally, 4.3461 grams of O₂ will be consumed.

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The developing chamber needs to be prepared because the solutions of the solute and solvent to dissolved.

What is a TLC plate?

TLC Plate Buying Guide Thin-layer chromatography (TLC), a standard analytical method for separating and identifying the chemicals in a given mixture, can also be used to assess the purity of a specific component included within that mixture. Gypsum and 60 G TLC Silica Gel Plates

What is the chamber process?

The Chamber technique, also known as the "lead-chamber process," is an industrial method for manufacturing sulfuric acid by oxidizing sulfur dioxide with moist air and employing gaseous nitrogen oxides as catalysts. The reaction is generally carried out in several sizable, box-like chambers made of sheet lead.

Simply replacing the watch glass with aluminum foil and getting the developing chamber ready before adding the TLC plates gives the solvent time to saturate, producing quicker and more repeatable results.

Therefore, the TLC plates gives the solvent time to saturate, producing quicker and more repeatable results.

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The Compare and contrast of metallic and ionic bonds is given below.

Ionic and metallic bonds take occur between positive and negative ions, whereas ionic bonds take place between positive ions and electrons. This is the main distinction between the two types of bonds.

Ions, which are made up of a positive and a negative ion, are created when two atoms exchange electrons. Atoms sharing electrons to form a molecule result in covalent bonds. Metal atoms shed their outermost electron to produce positively charged ions, which then form metallic bonds.

Metal ions are attracted to delocalized or free e, forming metallic connections as a result. whereas ionic bonds are created by electron transfer from one atom to another.

Similar to ionic bonds, where the removal of electrons results in the formation of ions, metallic bonds include the removal of electrons to create a sea of electrons.

Later, these electrons are used or shared by each and every atom, and in covalent bonds, two atoms share one electron. Consequently, metallic bonds resemble both ionic and covalent bonds.

Ionic and metallic solids differ significantly in that metallic solids contain metal atoms and free electrons while ionic solids mostly comprise cations and anions.

Additionally, metallic solids feature metallic bonds rather than the electrostatic attraction forces between cations and anions that exist in ionic solids.

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The heat capacity of 185g of liquid water is 4.421 J/g°C

Heat capacity is defined as the amount of heat energy required to raise the temperature of a given quantity of matter by one degree Celsius

Here given data is

Mass =  185g

We have to calculate the heat capacity = ?

So the formula is

q = m×c×ΔT

c = ?

q =  4.184 J

m = 185g

ΔT = 100°C

c =  m× ΔT/q

c =  185g ×100°C/ 4.184 J

c = 4.421 J/g°C

Heat capacity of 185g of liquid water is 4.421 J/g°C

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The products of an exothermic reaction likely to be warmer than the reactants because in this reaction energy produced is released as heat.

An exothermic reaction is a reaction in which energy is released in the form of light or heat. So, in an exothermic reaction, energy is transferred into the surroundings rather than taking energy from the surroundings as in the case of endothermic reaction.

We can also say that the exothermic reactions are the ones that actually release heat after the chemical reactions. For example matching a light using a matchstick is one example of this type of reaction where the release of energy  is in the form of both heat and light.

So, in these kinds of reaction the products of these reactions are more likely to me warmer than the reactants.

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The rank of the species by radius from largest to smallest:                    [tex]S^{2-} > Cl^{-} > Ar > K^{+} > Ca^{2+}[/tex]

All Ions are isoelectronic, which means the elements can have the same number of electrons but, their radii would be different because they have different nuclear charges. Atomic radii can be predicted easily. The atomic radii in the periodic table increase from top to bottom coming from left to right.

The cation with a greater positive charge will have a small radius due to the great attraction of electrons. The Anion with a greater negative charge will have a large radius due to the less attraction of electrons. Therefore, the ion will expand in size due to the net repulsion of the electrons.

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Answer:

86.06 amu is the average atomic mass of element Zz.

Explanation:

We may find the average atomic mass of Zz with a simple thought experiment.  Let's imagine that we were given 100.0 grams of Zz.  We know that 87.20% of that 100.0 grams is an isotope having 85.96 AMU (atomic mass units).  That means the other 12.80% must be the isotope with 86.78 AMU.

Since we picked 100.0 grams, it is easy to see that we would have:

87.2 grams of 85.96 AMU, and

12.8 grams of  86.78 AMU

-----------

100.0 grams total

The contribution of each isotope can be calculated by taking it's percent abundance times it's AMU andf then adding the total results:

AMU        %       Contribution to total AMU

85.96      87.2       74.96

86.78       12.8        11.11

--------      ---------      -----------

               100.0      86.06 amu

The sum of the two weighted averaged amu numbers is the average atomic mass of element Zz.  [Element Zz has a good futire as a sleep aid.]

A buffer is a solution which can resist a change in the pH on addition of a small amount of an acid or a base.

Case 1:  There is an acidic buffer containing a weak acid CH3COOH and salt of its conjugate base CH3COONa.

Explanation of how a buffer works:

The  following reaction would take place:

HCl + CH3COONa +   CH3COOH + NaCl

If a small amount of bases added, then CH3COOH acts as a buffering agent and the following reaction would take place:

NaOH+ CH3COOH +  CH3COONa  + H2O

Hence, when the acetic acid/sodium acetate buffer is titrated with NaOH, The buffering agent is CH3COOH and reaction(1) will occur.

CH3COOH + -OH ⟶ CH3COO + H2O

Case 2:  There is an basic buffer containing a weak base NH4OH and salt of its conjugate acid NH4OH.

The following reaction would take place:

HCl + NH4OH+ =  NH4Cl + H2O

NaOH(aq) + NH4Cl(aq) 1  NH4OH(aq) + H2O(

When the ammonium chloride buffer is titrated with HCl reaction  will occur.

NH3(aq) + H3O+(aq) ⟶ NH4+(aq) + H2O

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Gas collecting bottle is 150 ml by volume then the mass of hydrogen gas that was collected is 3.48 gram

Mass is a measure of the amount of matter in a substance or an object

Here given data is

Volume = 150 ml

Density of H₂ gas = 0.000523

So we have to calculate mass = ?

Mass = density/volume

Mass = 0.000523/150 ml

Mass = 3.48 gram

Mass of hydrogen gas that was collected is 3.48 gram

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the energy, in j, of light that must be absorbed by a hydrogen atom to transition an electron from n is 2.179 x 10^-18J.

The most important thing that people should know about hydrogen is that it is the most abundant element in the universe.

Some characteristics of hydrogen are:

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The woven cloth is a good choice for modeling a cell membrane because cell membranes are semipermeable, which means some particles can cross the cell membrane while others cannot. Unlike the plastic bag, the woven cloth is semipermeable: for the woven cloth, small particles/liquids can pass through it while larger objects cannot. However, nothing is able to pass through the plastic bag, so the plastic bag is not semipermeable (it's impermeable).

Yes, this small amount of water will have effect on the determined value for the concentration of the acid.

Even small amount of water causes an error because the drops of water add to the volume of base, diluting it slightly. This means it will take more base solution to neutralize the acid. This makes it seem as if the acidic solution was of stronger concentration than it actually was.

Method of quantitative analysis for determining the concentration of an acid or base by neutralizing it exactly with a standard solution of base or acid having known concentration is known as an acid–base titration

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Answer: When carbon(C) combines with chlorine(Cl), carbon forms single covalent bond with each chlorine atom. The valence shell configuration of uncombined C atom is 2s2 2px1 2py1 .

During combination hybridisation takes place, an electron shifts from 2s to empty 2pz . These four orbitals merge to form four hybrid orbitals. Each hybrid orbital has 1 electron which pairs up with a valence electron of Cl atom to form a covalent bond. Thus the four hybrid orbitals form four single covalent bonds with four chlorine atoms. This completes each atom's octet and gives them noble gas configuration.

When two atoms of different elements combine they always have electronegativity(EN) difference due to which the shared pair of electrons is more closer to more electronegative atom. This gives the bonds some ionic character. So no bond between two atoms of different elements can be purely covalent.

Explanation:

The correct answer is 0.161.

Solution:

Percentage transmission (%T) of the sample = 15.6

Therefore, Absorbance (A)  2 – log (%T) = 2 – log (15.6) = 0.8069

Use Beer’s law:

A = ε*c*l where ε = molar absorptivity of the solution, c = concentration of the solution, and l = path length of the solution.

Given A = 0.8069 and l = 5.00 cm, we must have

0.8069 = ε*c*(5.00 cm)

ε*c = 0.16138 cm-1

For the next part, assume that ε*c remains constant and we have

A’ = ε*c*l’ where l = 1.00 cm.

Plug in values and write

A’ = (0.16138 cm-1)*(1.00 cm) = 0.16138

Absorption measures the amount of light of a particular wavelength that a particular substance blocks from passing. The two main factors that affect absorption are substance concentration and optical path length. The net Absorption Rate is calculated using the formula of the total vacant area at the beginning of the period plus square feet.

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The temperature at constant volume is 0.311, The temperature at constant pressure is 5.133.

What is mixture?

A mixture in chemistry is a compound composed of two or more chemical components that are not chemically linked. A mixture is a physical combination of two or more substances that retain their identities and are blended as solutions, suspensions, or colloids.

GIVEN :

Air = 200%

p = 77f, 1 atm

PV=nRT

1*200/100 = 12(77)T

= 0.3311

1*80/100 = 12(77)T

= 5.133

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A. None of these is a true statement because

Phosphorus has 5 electrons in its outermost shell

Arsenic has 5 electrons in its outermost shell

Boron has 6 electrons in its outermost shell

Silicon has 4 electrons in its outermost shell

A mineral called phosphorus is found in many foods naturally and can also be taken as a supplement. It is a crucial component of cell membranes, bones, and teeth. It maintains a normal range of blood pH and aids in the activation of enzymes.

Many countries' groundwater naturally contains large amounts of arsenic.

Inorganic arsenic is extremely poisonous.

The greatest threat to public health from arsenic comes from contaminated water used for drinking, food preparation, and irrigation of food crops.

The only non-metallic element in group 13 of the periodic table is boron. Boron lacks electrons and has an empty p-orbital. Amorphous boron, a dark powder that is inert to oxygen, water, acids, and alkalis, is the most prevalent form of boron.

Chemical element silicon has the chemical symbol Si and atomic number 14. It is a tetravalent metalloid and semiconductor that has a blue-grey metallic sheen and is a hard, brittle crystalline solid. It belongs to the periodic table's group 14.

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Arrangement of the solution By increasing order of molarity, is

  option (a) < option (d) < option (b) < option (f) < option (c) < option (e)

Molarity is the amount of a substance in a certain volume of a solution. It is expressed as mole of the solute per liter of the solution. It is also known as molar concentration of the solution.

1M NaCl has, (1M Nacl/1L) . (1 molcl/1 mol) =1M.so the molarity of the  Nacl is 1M.

1M FeCl3 have, ( 1M FeCl3 /1L ). (3 mol Cl /1 mol) = 3M. So. the molarity of the 1M Fecl3 is 3M.

5 m Nacl has, (5m Nacl/1l) . (1 mol cl/1 mole) =5M it has the molariry of 5M.

1M Cacl2 has, (1M Cacl2/1L) . (2mol cl/1 mole) = 2 mol. so it has the molarity of 2M.

2M Fecl3 has, (2M Fecl3 /1L) . (3mol cl/1 mole) = 6M. it has the molarity of 6M.

2M Cacl2 has, (2M Cacl2/1L) . (2mol cl /1 mole)=4M.The molar concentration of this is 4M.

hence, the solutions are arranged in increasing order.

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The balanced equation of the reaction and the reaction types are given below as follows:

a. C₃H₈ +   5 O₂ → 3 CO₂ + 4 H₂O Reaction Type: Combustion

b. Ca +  Mg(NO₃)₂ → Mg + Ca(NO₃)₂ Reaction Type: Single replacement

d. 4 Na +  O₂ → 2 Na₂O Reaction Type: Oxidation or combination

e. 2 MgO → 2 Mg + O₂ Reaction Type: Decomposition

f. 2 K +  Cl₂ → 2 KClReaction Type: Synthesis

Chemical reactions are reactions in which chemical changes occur in one or more substances resulting in the formation of new substances.

Chemical changes that occur during chemical reactions are not easily reversible.

There are several types of chemical reactions and they include the following:

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In quasi-chemical theory of solutions, the enthalpy of mixing of the system can be expressed, the fraction of B (Xb) in the system will be 0.0729

ΔH = XaXb (7500 Xa + 18200 Xb)

Bond energies are as:

eaa = -6.5 × 10⁻²⁰

ebb = -5.3 × 10⁻²⁰ J/mol

eab = -5.4 × 10⁻²⁰ J /mol

The charge in internal energy will be

    Δe = eab - 1/2 (eaa + ebb)

    Δe =  -5.4 × 10⁻²⁰ J /mol - 1/2 (-6.5 × 10⁻²⁰ -  (-5.3 × 10⁻²⁰  J/mol)

    Δe = 6.4 × 10⁻²⁰

enthalpy of mixing will be

    ΔH mix = N₀.Z.XaXbΔe

    ΔH mix = 6.0221 × 10²³ × 4 × Xa.Xb × 6.4 × 10⁻²⁰       (2)

We have

    ΔH = XaXb (7500 Xa + 18200 Xb)        (1)

(1) = (2)

    154.165 × 10³ = 7500 Xa + 18200 Xb

As Xa = 1 - Xb

put in above eq.

    154.165 × 10³ = 7500 (1 - Xb) + 18200 Xb

    146665 = 10700 Xb

    Xb = 0.0729

So fraction of B(Xb) = 0.0729

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Like all automotive antifreeze compounds, they are 38.7% carbon. So carbon is 38.7 9.7% hydrogen, 9.7 hydrogen and 51.6% oxygen. all right. Ah 1500 6% oxygen. yes. all right. Next, we need to empirically find molecular phone lines emitted from the ground.

Well, first of all, yes there are more. We have the atomic weight of carbon. 1201 Oxygen 16. The process divides each percentage by the fractional mass by 50%. So divided by 3 good points to find 38.7. This is 9.7 divided by 1, which is 9.7, and 51.6 divided by 16, which is 5157 divided by 16. I want to believe all right. The next step is to share each. youngest age. The minimum he is 3.225. If you're sharing now, we're sharing 3.225 times 3.225 is one 9.7 x 3.225. Approximately 3 and 3.225 divided by 3.225. So we have an empirical formula where carbon is 1, hydrogen is 3, and oxygen is 1. See below for 3. A small amount of Italian black hole was given. First find the molecular formula. The empirical mass is 2, 3, 16, which is 12 plus 1. So 15 plus 7 30 from g Berman. This is the molecular formula of the molecule. Therefore, we can find the sector of the mass of the molecular formula divided by the mass of the empirical formula. Remember that we are using this subdivision. Thus, for molecular  and larger LAMAs.

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The concentration of a solution expressed in moles of solute per 1L of solution is called either the molarity or the molar concentration.

A solution is a homogenous mixture of one or more solutes dissolved in solvent. An example of solution is salt and water.

The most common way to express solution concentration is molarity(M) which is defined as the amount of solute in moles divided by the volume of solution in liters.

Molar concentration is a measure of the concentration of a chemical species.

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