Select all correct statements from below. a. Recrystallization is a technique used to purify solid compounds based on solubility differences at different temperatures. b. Toluene is a clear, colorless liquid which becomes a vapor when exposed to air at room temperature. Do not breathe in. Always handle it in the fume hood. c. Filtration is a technique to separate solid from liquid(s). d. There are two different filtration techniques: Gravity Filtration and Vacuum Filtration.

Answer:

Swedish physicist Johannes Rydberg

Explanation:

Answer:

Six-membered cyclic hemiacetals and five-membered cyclic hemiacetals are called, respectively, mannoses and xyloses.

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10.5 milliliters of 3.5 M zinc hydroxide react completely with 15.0 milliliters of 4.9 M nitric acid.

It is a unit of concentration equivalent to moles of solute per liter of solution.

Zn(OH)₂ + 2 HNO₃ ⇒ Zn(NO₃)₂ + 2 H₂O

10.5 mL of 3.5 M Zn(OH)₂ react.

0.0105 L × 3.5 mol/L = 0.037 mol

The molar ratio of Zn(OH)₂ to HNO₃ is 1:2.

0.037 mol Zn(OH)₂ × 2 mol HNO₃/1 mol Zn(OH)₂ = 0.074 mol HNO₃

[HNO₃] = 0.074 mol / 0.0150 L = 4.9 M

10.5 milliliters of 3.5 M zinc hydroxide react completely with 15.0 milliliters of 4.9 M nitric acid.

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answer

Please add answer choice

Explanation:

Answer:

Explanation:

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The value of E determined as shown in the question is a chemical property.

A chemical property has to do with the chemical changes that occur in a substance. Now we know that The value E refers to how easily a substance could accept or loose electrons.

Thus, the value of E determined as shown in the question is a chemical property.

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False. The principle states that the buoyant force on an object is equal to the weight of the fluid displaced by the object.

It is a theory propounded by Archimedes. It opines that a floating body is acted upon by a buoyant force.

The buoyant force is the same as the weight of the fluid displaced by the floating body.

Thus, instead of saying 'the buoyant force is equal to the blank of the fluid displaced', it is actually 'the buoyant force is equal to the weight of the fluid displaced'.

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Answer:

metals tend to lose electrons to form positive ions because they have more protons than electrons.

Atomic radius is1.349*10-23

hcp unit cell you can see that that the spheres touch each other along

so 2rMg = a where rMg is the radius of a Mg ion and = 0.6745*10^-23

There are three levels of atoms in the hcp structure.

Six atoms form a hexagonal arrangement in the top and bottom layers, while a seventh atom sits in the centre of the hexagonal arrangement.

Three atoms in the intermediate layer are tucked away in the top and bottom plane's triangular grooves.

Mg hcp c/a = 1.635

hcp is close-packed example ABABAB etc

V = sin(60)*a*a*1.635 a

V = 1.635 *0.866*a^3

V = 1.887*a^3 cm3

Z = 2 (atoms inside unit cell)

Mass inside unit cell is = (2 * 24.305)/(6.022*10^23) = 8.071*10^-23 g

D =M/V

1.74 = 8.071*10^-23/1.887*a^3

a^3 = 8.071*10^-23/1.887*1.74 = 2.458*10^-23

a = 1.349*10^-23

Hence Atomic radius is 1.349*10^-23

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The molecular formula of the compound is [tex]Cr_{2}S_{3}O_{12}[/tex].

Mass of Cr = 0.70 g

Mass of S = 0.65 g

Mass of O = 1.30 g

Molecular mass = 392.2 g

Moles of Cr = [tex]\frac{0.70}{52.0}[/tex]

                  = 0.01346 mol

Moles of S = [tex]\frac{0.65}{32.06}[/tex]

                  = 0.02025 mol

Moles of O = [tex]\frac{1.30}{16.0}[/tex]

                   = 0.08125 mol

Dividing both sides with lower quantity ;

[tex]Cr_{\frac{0.01346}{0.01346} } S_{\frac{0.2025}{0.01346} } O _{\frac{0.08125}{0.01346} }[/tex]≅ [tex]CS_{1.5} O_{6}[/tex]

And [tex](empirical formula )_{n} = molecular formula[/tex]

                        392.2 = n (52.0 + 6 × 16.0)

                                  n = 2

Therefore, the molecular formula of the compound is [tex]Cr_{2}S_{3}O_{12}[/tex].

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55.44 K is the temperature that need to change in order for the neon gas to be 39.0% faster than the RMS speed of the argon.

Given

RMS speed of argon = 1.20 km/sec = 1.20 ×[tex]10^{3}[/tex] m/sec

RMS speed of neon = 39% faster than the speed of argon

                                 = RMS speed of argon + [tex]\frac{39}{100}[/tex] RMS speed of argon

                                 = RMS speed of argon ( 1 +0.39)

RMS speed of neon = 1.39 times of RMS speed of argon

Hence   [tex]\frac{v_{ne} }{v_{ar} } = \frac{1.39}{1}[/tex] … (1)

The atomic mass of argon is 39.95 g/mol = 39.95×[tex]10^{-3}[/tex] Kg/mol

and  the atomic mass of neon is 20.18 g/mol = 20.18 ×[tex]10^{-3}[/tex] Kg/mol

According to the formula of root-mean-square velocities of gas molecules

[tex]v_{rms} = \sqrt{3RT/M}[/tex] where,

[tex]v_{rms}[/tex] = root-mean-square velocity

M = molar mass of gas (in kg per mole)

R = Molar gas constant = 8.314 J/mol/K

T = temperature (in kelvin)

[tex]v_{arg }[/tex] = [tex]\sqrt{3RT_{arg}/M }[/tex]

[tex]v_{arg} ^{2}[/tex] = [tex]3RT_{arg} /M[/tex]

1.20 ×1.20 ×[tex]10^{6\\[/tex] = 3 ×8.314×[tex]T_{arg}[/tex] /39.95 ×[tex]10^{-3}[/tex]

[tex]T_{arg}[/tex] = 1.44 × 39.95 ×[tex]10^{3}[/tex] / 24.942

[tex]T_{arg}[/tex] = 2306.47 K

Now,

RMS velocity is directly proportional to [tex]\sqrt{T}[/tex] and inversely proportional to [tex]\sqrt{M}[/tex]

[tex]v_{rms}[/tex] [tex]\alpha[/tex] [tex]\sqrt{T}[/tex]   and  [tex]v_{rms} \frac{1}{\alpha } \sqrt{M}[/tex]

[tex]\frac{v_{ne} }{v_{ar} }[/tex] =  [tex]\sqrt{\frac{T_{ne} }{T_{ar} } }[/tex]× [tex]\sqrt{\frac{M_{ar} }{M_{ne} } }[/tex]

According to equation 1

[tex]\sqrt{\frac{T_{ne} }{T_{ar} } }[/tex] × [tex]\sqrt{\frac{M_{ar} }{M_{ne} } }[/tex] = 1.39

[tex]T_{ne}[/tex] = 1.39 ×1.39 × 2306.47 × 20.18 / 39.95

[tex]T_{ne}[/tex] = 2251.03K

Change in temp ΔT = 2306.47-2251.03= 55.44 K

Hence, 55.44 K is the temperature that need to change in order for the neon gas to be 39.0% faster than the RMS speed of the argon.

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Candle wax is made up of several hydrocarbons with the general formula [tex](CH_2)_n[/tex] , where n is a large number.

Hydrocarbon's on reaction with oxygen forms carbon-dioxide and water vapor. This is called combustion reaction.

                                   [tex](CH_2)_n + O_2 \rightarrow CO_2 + H_2O[/tex]

After few minutes, you will observe that the transparent lid is now opaque and there are traces of water deposited on the surface of lid.

Conclusion -  the lid is opaque due to the carbon-dioxide formed and water vapors are condensed on the surface of lid.

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Answer:

See explanation

Explanation:

Microwaves work by flipping water molecules upside down, then right side up again, and so on at very high speeds, and the friction generates heat. Some glass or plastic isn't affected by the microwaves, so the molecules don't get flipped, and so no friction occurs and no heat is produced, leading to the dish not being heated up.

4.235 is the pH of a solution that is 0.175M benzoic acid and 0.190M sodium benzoate, a salt whose anion is the conjugate base of benzoic acid.

According to Henderson Hasslbalch Equation to calculate the pH of a solution is expressed as

[tex]pH = pK_{a} + \log \frac{[\text{Congujate base}]}{[\text{Weak acid}]}[/tex]

Benzoic acid (C₆H₅COOH) and its conjugate base is Benzoate (C₆H₅COO⁻) are considered as acidic buffer.    

Kₐ for benzoic acid = 6.3 × 10⁻⁵

So, pKₐ = -log Kₐ

             = - log [6.3 × 10⁻⁵]

             = 4.2

Now put the value in above expression we get

[tex]pH = pK_{a} + \log \frac{[\text{Congujate base}]}{[\text{Weak acid}]}[/tex]

[tex]pH = pK_{a} + \log \frac{C_6H_5COONa}{C_6H_5COOH}[/tex]

     [tex]= 4.2 + \log \frac{0.190}{0.175}[/tex]

     = 4.2 + 0.035

     = 4.235

Thus from the above conclusion we can say that 4.235 is the pH of a solution that is 0.175M benzoic acid and 0.190M sodium benzoate, a salt whose anion is the conjugate base of benzoic acid.

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Answer:

2.62 atm

Explanation:

1 atm = 14.6959 psi

38.5 / 14.6959 = 2.62 atm

The distance moved by the solvent is 9.5 cm.

Given,

Rf value of yellow dye = 0.60

Distance moved by yellow distance = 5.7 cm

To calculate,

Distance moved by the solvent =?

We know that the Rf value in chromatography is calculated as:

Rf = distance moved by the solute/ distance moved by the solvent

Putting the given values in the above formula, we get

0.60 = 5.7/ distance moved by solvent

Distance moved by the solvent = 5.7/0.60

Distance moved by solvent = 9.5 cm

The ratio of the analyte's (solute) distance traveled to the solvent front on a chromatogram is known as the retention factor (Rf) value.

When using mobile solvents, analytes move differently depending on the type of chromatographic procedure used to transfer them to the stationary phases. The differences between analytes' affinity for stationary and mobile solvents are what cause this difference. The longer an analyte is in place, the lower its Rf value will be, and vice versa, depending on its relative affinity with a stationary phase.

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Answer: The pressure of the gas is 4.4334atm.

Explanation:

The ideal gas law for pressure is shown as: [tex]P=\frac{nRT}{V}[/tex].

~n=number of moles (mol)

~R=ideal gas constant=[tex]0.0821\frac{L*atm}{mol*K}[/tex]

~T=temperature (K)

~V= volume (L)

We are not given the number of moles, but we can find that with the grams of CO₂ that we were given. This is also better because we have the compound as well, making it easier to find its molar mass on the periodic table.

[tex]8.06gCO_{2} *\frac{1molCO_{2} }{44.009gCO_{2} }=0.18molCO_{2}[/tex]

Now we are ready to plug our given information into the formula for the ideal gas law of pressure.

[tex]P=\frac{0.18mol*0.0821\frac{L*atm}{mol*K}*300K }{1.00L}[/tex]     [tex]P=4.4334atm[/tex]

Given the work above, the pressure of the gas is 4.4334 atmospheres.

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Answer:

A person spends Rs. 10,000 per second.

In one year, he will spend = Rs. (10,000 x 3600 x 24×365) = Rs. 3.1536 x 10^11

1 mole rupees = Rs. 6.022 x 10^23

So it will take approximately 1.91 x 1012 years to spend 1 mole rupees.

Explanation:

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In the bohr model of the hydrogen atom, the energy required to excite an electron from n = 2 to n = 3 is greater than the energy required to excite an electron from n = 3 to n = 4

Bohr's energy levels:

The essential concept of Bohr's atomic model is that electrons occupy specified orbitals that call for the electron to have a certain amount of energy. An electron needs to be in one of the permitted orbitals and have the correct amount of energy needed for that orbit in order to be in the electron cloud of an atom. An electron would require less energy to orbit near the nucleus, while an electron would need more energy to orbit away from the nucleus. Energy levels are the potential orbits. One of Bohr's models' flaws was that he was unable to explain why just specific energy levels or orbits were permitted.

It is evident that the energy required to escape an electron from n=2 to n=3 is greater than the energy required to exit an electron from n=3 to n=4. This is because as n increases, the energy levels move closer to one another.

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Answer:

Different elements

Explanation:

The variable, the bottom number, and the top number all reveal something about each other. The number at the bottom is the element's atomic number, and because both of these pairs have different atomic numbers, they are different elements in general.

The daily maximum of just sodium (Na) should be = 6000 mg

The adult's daily maximum intake of salt = 6g

The major element of salt that causes health concerns is sodium (Na).

Therefore the quantity of sodium consumed in milligrammes= 6×1000

= 6000 mg

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Answer:-
A Solution of salt in Water
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Answer: B) a solution of salt in water

Explanation:

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Answer:

2 million years

Explanation:

500/2000 = 1/4, meaning the sample decayed to 1/4 of its original amount. From this, we can conclude that 2 half lives have passed.

In the problem, we are given one half life is 1 million years. Multiplying this by 2, we get that 2 half lives is 2 million years.

Diamond is a network solid.

In diamond, carbon atoms are bonded together by extended covalent bonds. Each carbon atom forms four strong covalent bonds with its neighboring carbon atoms, creating a three-dimensional network of carbon-carbon bonds throughout the crystal lattice.

Diamond is a type of solid known as a covalent network solid. In covalent network solids, the atoms are held together by a network of strong covalent bonds, extending throughout the entire crystal structure. This results in a very rigid and hard material with high melting and boiling points.

Other examples of covalent network solids include graphite and quartz. Due to its strong and interconnected carbon-carbon bonds, diamond is renowned for its exceptional hardness and is one of the hardest known naturally occurring materials.

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The concentration of sulfate ion would be required for Ca⁺ to begin to precipitate out as calcium sulfate is 7.10 * 10⁻⁴ M.

b) The concentration of the Ba²⁺ ion would be 9.929 * 10⁻² M

The precipitation of calcium sulfate occurs when the ionic product, Kip is greater than or equal to the solubility product, Ksp of calcium sulfate.

a) The equation of the dissociation of CaSO₄ is given below:

CaSO₄ ⇄ Ca²⁺ + SO₄²⁻

Ksp = [Ca²⁺] * [SO₄²⁻] = 7.10 * 10⁻⁵

Kip = [Ca²⁺] * [SO₄²⁻]

[SO₄²⁻] = Kip/[Ca²⁺]

[Ca²⁺] = 0.100 M

For precipitation to occur;

Kip = Ksp = 7.10 * 10⁻⁵

[SO₄²⁻] = 7.10 * 10⁻⁵/0.100

[SO₄²⁻] = 7.10 * 10⁻⁴ M

Therefore, the concentration of sulfate ion would be required for Ca⁺ to begin to precipitate out as calcium sulfate is 7.10 * 10⁻⁴ M.

b) The concentration of the Ba²⁺ ion would be;

0.100 M - 7.10 * 10⁻⁴ M = 9.929 * 10⁻² M

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Answer:

See below

Explanation:

Molecular formula  ( just write down all of the elements )   C 4 H4 O4

Empiracle formual    CHO

"Molecular formulas tell you how many atoms of each element are in a compound, and empirical formulas tell you the simplest or most reduced ratio of elements in a compound"

3.73 x[tex]10^{-3}[/tex] the rate of change of [tex]ClF_3[/tex] if the concentration of [tex]F_2[/tex]decreases from 0.950 M to 0.865 M over 15 seconds.

The rate of change is used to mathematically describe the percentage change in value over a defined period of time, and it represents the momentum of a variable.

[tex]Cl_2(g)+3F_2(g)[/tex]→[tex]2ClF_3(g)[/tex]

Rate of change of [tex]F_2[/tex] = [tex]\frac{Change \;in \;concemtration}{Time}[/tex]

Rate of change of[tex]F_2[/tex] = [tex]\frac{0.950 M-0.865 M}{15 seconds}[/tex]

Rate of change of [tex]F_2[/tex] = 5.6 x [tex]10^{-3}[/tex]

[tex]\frac{Rate of change of F_2}{3}[/tex] =[tex]\frac{Rate \;of c\;hange \;of\;ClF_3}{2}[/tex]

[tex]\frac{5.6 X 10^{-3}}{3}[/tex]=[tex]\frac{Rate \;of \;change \;of \;ClF_3}{2}[/tex]

Rate of change of [tex]ClF_3[/tex] =1.866666667 x2 x[tex]10^{-3}[/tex]

Rate of change of [tex]ClF_3[/tex]= 3.73 x [tex]10^{-3}[/tex]

Hence, 3.73 x[tex]10^{-3}[/tex] the rate of change of [tex]ClF_3[/tex] if the concentration of [tex]F_2[/tex]decreases from 0.950 M to 0.865 M over 15 seconds.

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A Calorie unit used in food is equal to the amount of energy necessary to raise the temperature of 1 kilogram of water by 1 degrees Celsius.

The amount of heat energy required to raise the temperature by 1 gram of water through 1°C is known as One Calorie.

1 Calorie = 4.18 J

Thus from the above conclusion we can say that A Calorie unit used in food is equal to the amount of energy necessary to raise the temperature of 1 kilogram of water by 1 degrees Celsius.

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The new pressure exerted by helium on its container is 2533.33 torr.

Boyle's law: For a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional. so PV= constant.

At constant temperature and moles,

P1V1 = P2V2.

The original sample is at 2atm torr and volume 5.00 L and then helium gas was compressed to 3.00 L

∴ P₁V₁ = P₂V₂

 (2× 760 torr)(5.00 L ) = (3.00 L )(x torr),

 x = 2533.33 torr.

 P₂ = 2533.33 torr.

Therefore, the new pressure exerted by helium on its container is 2533.33 torr.

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The volume of HCl required is 23.89 mL

Calculation of volume:

The reaction:

[tex]HCl + NaOH \rightarrow NaCl + H_2O[/tex]

As HCl and NaOH react in 1 : 1 ratio.

Volume of NaOH= 718 mL

Concentration= 0.183M

Volume of HCl= ?

Concentration= 5.50M

Using the dilution formula:

[tex]M_1\times V_1(NaOH)= M_2\times V_2(HCl)[/tex]

[tex]0.183\times 718= 5.50 \times V_2\\V_2=\frac{131.394}{5.50} \\V_2 = 23.89 \,mL[/tex]

Therefore,

Volume of HCl required will be 23.89 mL.

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Simple

Look at Electronic configuration of Al

It has valency as 3

So it can make 3 bonds

So

Aluminium does bonding with 3 chlorine atoms

There is another reason

That's electronegativity

As difference in electronegativity is higher they forms ionic bond