12. In the modern periodic table, which of the following describes the elements with similar
properties?
A. They have similar atomic masses.
B. They are located in the same group.
C. They are located in the same period.
D. They have the same number of protons.

Answer:

Specififc rotation [∝] = 0.5° mL/g.dm

Explanation:

Given that:

mass = 400 mg

volume = 10 mL

For a solution,

The Concentration = mass/volume

Concentration = 400/10

Concentration = 40 g/mL

The path length l = 20 cm = 2 dm

Observed rotation [∝] = + 40°

Specififc rotation [∝] = ∝/l × c

where;

l = path length

c = concentration

Specififc rotation [∝] = (40 / 2 × 40)

Specififc rotation [∝] = 0.5° mL/g.dm

Using the specific rotation formular, the specific rotation obtained for the compound ls 5°

Given the Parameters :

Concentration, C

Concentration = mass × volume

Mass = 400 mg = 400 /1000 = 0.4g

Volume = 10 mL

Concentration = 0.4g × 10 mL = 4g/mL

The specific rotation formular, [tex] [\alpha] [/tex] is given by :

[tex] [\alpha] = \frac{\alpha_{observed}}{C \times l} [/tex]

[tex] [\alpha] = \frac{40°}{4 \times 2} = \frac{40°}{8} = 5° [/tex]

Therefore, the specific rotation of the compound ls 5°

Learn more :https://brainly.com/question/5963685?referrer=searchResults

Answer:

infinite

Explanation:

Answer:

O2

Explanation:

Diatomic molecules are molecules that have 2 of either H,N,F,O,I,Cl, or Br. In this case, 2H is not correct because the 2 is in front of the element name. Diatomic molecules will have the two after which means that the molecule has these two elements together.

Answer:

0.150 M

Explanation:

The molarity of the solution can be calculated using the formula;

C1V1 = C2V2

Where; C1 = initial concentration of solution

C2 = final concentration of solution

V1 = volume of initial solution

V2 = volume of final solution

According to this question, C1 = 0.200M, C2 = ?, V1 = 75mL, V2 = 100.0mL

Hence,

C1V1 = C2V2

0.200 × 75 = C2 × 100

15 = 100C2

C2 = 15/100

C2 = 0.150M

Therefore, the molarity of the final KCl solution is 0.150M

Answer:

See explanation

Explanation:

A drying tube prevents moisture from contaminating the reactants. The drying tube contains CaCl2 a hygroscopic material whose function is to absorb the moisture so that it does not react with the Grignard reagent. Without the desiccating action of CaCl2, moisture will enter the reaction chamber,contaminating the reactants.

If water reacts with the Grignard reagent, an alkane is formed. The mechanism of this reaction is shown in the image attached. R here represents the alkyl moiety of the Grignard reagent.

Answer:

1.63cm

Explanation:

Given parameters:

Density of silicon = 2.13g/cm³

Mass of Cr₂O₃ = 88.3g

Width of the block = 2.65cm

Length of the block  = 2.65cm

Unknown:

Thickness of the block  = ?

Solution:

Reaction equation:

          3Si   +   2Cr₂O₃   →  3SiO₂ + 4Cr

Let us find the mass of Si,

   So,

    Number of moles  = [tex]\frac{mass}{molar mass}[/tex]

  we find the number of moles of Cr₂O₃ ;

Molar mass of Cr₂O₃ = 2(52) + 3(16) = 152g/mol

  Number of moles of Cr₂O₃ = [tex]\frac{88.3}{152}[/tex]   = 0.58mole

Then;

  we know that;

              2 moles of Cr₂O₃ reacted with 3 moles of Cr₂O₃

              0.58moles of Cr₂O₃ will react with [tex]\frac{0.58 x 3}{2}[/tex]   = 0.87mole

So,

    Mass of Si  = number of moles x molar mass

          molar mass of Si = 28g/mol

   Mass of Si  = 0.87 x 28  = 24.4g

Since density is the mass per unit volume of a compound;

     Mass of Si  = density of Si x volume of Si block

  Volume of Si block  = length x width x thickness = 2.65 x 2.65 x thickness

   Volume of Si block = 7.02 x thickness

Mass of Si  = 2.13 x 7.02 x thickness

    24.4  = 15 x thickness

         thickness = [tex]\frac{24.4}{15}[/tex] = 1.63cm

Answer:

XH₂ = 0.4885

XN₂ = 0.4290

XAr = 0.0825

Explanation:

Step 1: Given data

Step 2: Calculate the total pressure (P)

The total pressure is equal to the sum of the partial pressures of all the gases.

P = pH₂ + pN₂ + pAr = 441.0 Torr + 387.3 Torr + 74.5 Torr = 902.8 Torr

Step 3: Calculate the mole fraction (X) of each gas

We will use the following expression.

Xi = pi / P

where,

Xi: mole fraction of the gas i

pi: partial pressure of the gas i

P: total pressure

XH₂ = pH₂ / P = 441.0 Torr / 902.8 Torr = 0.4885

XN₂ = pN₂ / P = 387.3 Torr / 902.8 Torr = 0.4290

XAr = pAr / P = 74.5 Torr / 902.8 Torr = 0.0825

Answer:

The mass of N a H C O 3 present is 2.431 g

Explanation:

The sample contains 57.2 % N a H C O 3  by mass.

To find the mass of N a H C O 3  in the sample, we need to find what the equivalent of 57.2 %.

Mass of N a H C O 3  = Percentage Composition * Mass of sample

Mass of N a H C O 3  = 57.2 / 100     * 4.25

Mass of N a H C O 3   = 2.431 g

The mass of N a H C O 3 present is 2.431 g

The mass of the compound (NaHCO₃) contained in 4.25 g is 2.431 g.

The given parameters;

The mass of the compound (NaHCO₃) contained in 4.25 g is calculated by the finding its equivalent in the given percent composition as follows;

[tex]mass \ = \frac{57.2}{100} \times 4.25\\\\mass = 2.431 \ g[/tex]

Thus, the mass of the compound (NaHCO₃) contained in 4.25 g is 2.431 g.

Learn more about percentage composition here: https://brainly.com/question/20065048

Answer:

B. are electrical signals.

Answer:

Fatty acids are fairly long linear hydrocarbon chains with a carboxylic acid group at one end. Fatty acids are named based on the number of carbon atoms and carbon-carbon double bonds in the chain. ... This bond could bind a molecule of hydrogen, forming a 16-carbon molecule with no carbon-carbon double bonds.

Explanation:

Fatty acids are the fundamental blocks of fat in our bodies and our meals.

Fatty acids are carboxylic acids with long aliphatic chains that can be branched or unbranched in biochemistry. Natural fatty acids have an even number of carbon atoms and are usually unbranched. Fatty acids are important components of lipids.

They exist as esters in three different forms:

Fatty acids that are vital to our bodies but cannot be produced in sufficient quantities within our cells are obtained from dietary sources. They are referred to as essential fatty acids. Linoleic acid and alpha-linoleic acid are two examples.

Fatty acids serve as energy sources as well as membrane constituents. They are involved in signaling, cell metabolism, and energy storage in adipose tissues.

To know more about Fatty acids,

brainly.com/question/29593274

Answer:

3

Explanation:

I wish you the best, its three or 2

Answer:

2

Explanation:

Edge 2021

The pressure can be increased by a factor of 3 by decreasing the volume by a factor of 3.

Given that the temperature of the system is held constant. So it implies that it is an isothermal process.

Now we know that the ideal gas equation is given by:

PV = nRT

where, P is the pressure

V is the volume

n is the number of moles

R is the gas constant, and

T is the temperature

Assuming n is constant, R is universal as constant, so if T is also constant, then:

PV = constant

So if P becomes 3P. that is the pressure increased by a factor of 3, then V must become V/3, so that: (3P)(V/3) = PV = constant.

Learn more about ideal gas:

https://brainly.com/question/11676583?referrer=searchResults

Answer: i think its protons and electrons but it also might just be atoms because protons and electrons  make atoms when there are also neutrons

Explanation:

Answer:

i wish i could help but t know either so i wish you luck for an answer once again truly sorry don'

Explanation:

i am sorry but i do not know :(

Answer:

Explanation:

Area of person's back = .18 m²

energy of radiation falling on the back per second

= 70 x .18 J

= 12.6J

Energy absorbed per second = .5 x 12.6 = 6.3 J

energy absorbed per hour = 6.3 x 60 x 60 = 22680 J

energy required to break one mole bond = 348 x 10³ J  

energy required to break one bond = 348 x 10³ / 6.02 x 10²³

= 57.8 x 10⁻²⁰ J .

So number of bonds broken in one hour = 22680 / 57.8 x 10⁻²⁰

= .392  x 10²³ bonds .

= 39.2 x 10²⁰ bonds .

Answer:

The actual concentration of the hydrochloric acid is 1.2M

Explanation:

The formula to be used here is that of concentration (popularly used during titration);

CₐVₐ/CbVb =nₐ/nb

where Cₐ is the concentration of acid (supposed to be 1.0 M but unsure)

Vₐ is the volume of acid (100 ml)

Cb is the concentration of base (1.3 M)

Vb is the volume of base (89.13 ml)

nₐ is the volume of acid

nb is the volume of base

The equation for the reaction described in the question is

HCl + NaOH ⇒ NaCl + H₂O

we can see from the above equation the ratio of the number of moles for both the acid and the base is 1:1

Thus;

Cₐ × 100/1.3 × 89.13 =1/1

Cₐ = 1.3 × 89.13/100

Cₐ = 1.2M

The actual concentration of the hydrochloric acid is 1.2M

Answer:

Explanation:

a) O₂(g) + 2H₂(g) = 2H₂O

b) H₂O(l) = H₂O(s)

c) NH₃(g) + HCl(g) =  NH₄Cl(g)

d) 2NH₄NO₃(s) =  2N₂(g) + O₂(g) + 4H₂O(g)

e) N₂O₄(g) =  2NO₂(g)

ΔS is positive when there is increase in disorderliness. It happens when there is increase in volume .

Increase is volume is maximus in the following reaction.

d) 2NH₄NO₃(s) =  2N₂(g) + O₂(g) + 4H₂O(g)

in this reaction solid NH₄NO₃ is changed to 7 x 22.4 L of gases so there is maximum increase in volume . Hence maximum increase in entropy . Hence ΔS is most positive .

Answer:

K = 0.0505

Explanation:

Based on the equilibrium:

N2O3 ⇄ NO2 + NO

K, equilibrium constant, is defined as:

K = [NO2] [NO] / [N2O3]

Where [] are the equilibrium concentration of each species in the mixture.

The initial molarity of N2O3 is:

1.191mol / 2.00L = 0.5955M

In equilibrium, 0.5955M of N2O3 reacts producing X Molar of NO2 and X Molar of NO:

[N2O3] = 0.5955M - X

[NO2] = X

[NO] = X

As equilibrium concentration of NO2 is 0.300mol/2.00L = 0.15M; X = 0.15M:

[N2O3] = 0.5955M - 0.15M = 0.4455M

[NO2] = 0.15M

[NO] = 0.15M

And K is:

K = [0.15M] [0.15M] / [0.4455M]

1) Both cells have a cell membrane.

2) A nucleus is present in only Eukaryote cells.

3) I'm pretty sure Prokaryote cells are bacteria.

Hope this helps!! :)

Answer:

1) easy compressed

2) fills its container

3) far more space

Explanation:

Answer:

A) enthalpy of reaction

Explanation:

The region C signifies the enthalpy of reaction.

This diagram is the energy profile of an endothermic reaction. In such reaction, heat is absorbed from the surrounding. At the end of the reaction, the heat of product is lesser than that of the reactants.

it is indeed A) enthalpy of reaction

Answer: It’s D

Explanation:

Cuz I said so

Answer: d. Shearing

Explanation:

Answer:

C. Hydrosphere for 7

B. Biosphere for 8

Explanation: I am not sure about the rest of them.

Answer:

The moon blocks the Sun's light from hitting the surface of the earth

Explanation:

Answer: the type of cup

Explanation: the independent variable is what you change in your experiment, to find out the different results, in this experiment the factor that they are changing in order to see which outcome is best, is the type of cup.

Answer:

The energy of each transition is approximately [tex]1.98\times 10^{-19}\; \rm J[/tex].

The frequency of photons released in such transitions is approximately [tex]3.00\times 10^{14}\; \rm Hz[/tex].

Explanation:

The Rydberg Equation gives the wavelength (in vacuum) of photons released when the electron of a hydrogen atom transitions from one main energy level to a lower one.

The Rydberg Equation gives the following relation:

[tex]\displaystyle \frac{1}{\lambda_\text{vac}} = R_\text{H} \cdot \left(\frac{1}{{n_2}^2}} -\frac{1}{{n_1}^2}\right)[/tex].

Rearrange to obtain and expression for [tex]\lambda_\text{vac}[/tex]:

[tex]\displaystyle \lambda_\text{vac} = \frac{1}{\displaystyle R_\text{H}\cdot \left(\frac{1}{{n_2}^2} - \frac{1}{{n_1}^2}\right)}[/tex].

In this question, [tex]n_1 = 7[/tex] while [tex]n_2 = 3[/tex]. Therefore:

[tex]\begin{aligned} \lambda_\text{vac} &= \frac{1}{\displaystyle R_\text{H}\cdot \left(\frac{1}{{n_2}^2} - \frac{1}{{n_1}^2}\right)} \\ &\approx \frac{1}{\displaystyle 1.09678 \times 10^{7}\; \rm m^{-1} \cdot \left(\frac{1}{3^2} - \frac{1}{7^2}\right)} \approx 1.0 \times 10^{-6}\; \rm m \end{aligned}[/tex].

Note, that [tex]1.0\times 10^{-6}\; \rm m[/tex] is equivalent to [tex]1000\; \rm nm[/tex]. That is: [tex]1.0\times 10^{-6}\; \rm m = 1000\; \rm nm[/tex].

Look up the speed of light in vacuum: [tex]c \approx 3.00\times 10^{8}\; \rm m \cdot s^{-1}[/tex]. Calculate the frequency of this photon:

[tex]\begin{aligned} f &= \frac{c}{\lambda_\text{vac}} \\ &\approx \frac{3.00\times 10^{8}\; \rm m\cdot s^{-1}}{1.0\times 10^{-6}\; \rm m} \approx 3.00 \times 10^{14}\; \rm Hz\end{aligned}[/tex].

Let [tex]h[/tex] represent Planck constant. The energy of a photon of wavelength [tex]f[/tex] would be [tex]E = h \cdot f[/tex].

Look up the Planck constant: [tex]h \approx 6.62607 \times 10^{-34}\; \rm J \cdot s[/tex]. With a frequency of [tex]3.00\times 10^{14}\; \rm Hz[/tex] ([tex]1\; \rm Hz = 1\; \rm s^{-1}[/tex],) the energy of each photon released in this transition would be:

[tex]\begin{aligned}E &= h \cdot f \\ &\approx 6.62607 \times 10^{-34}\; \rm J\cdot s^{-1} \times 3.00 \times 10^{14}\; \rm s^{-1} \\ &\approx 1.98 \times 10^{-19}\; \rm J\end{aligned}[/tex].

The energy of the transition between n = 7 and n = 3  is 1.96 × 10^-19 J while the frequency is 3 × 10^14 Hz.

Using the Rydberg Equation for energy;

ΔE = -RH(1/n^2final - 1/n^2initial)

Given that;

nfinal = 3

ninitial = 7

RH = 2.18 × 10^-18 J

ΔE = - 2.18 × 10^-18(1/3^2 - 1/7^2)

ΔE = - 2.18 × 10^-18(0.11 - 0.02)

ΔE = - 1.96 × 10^-19 J

For the second part;

Since the wavelength is 1000nm, we have;

λ = 1000nm

c = 3 × 10^8 m/s

f = ?

c = λf

f = c/λ

f = 3 × 10^8 m/s/1000 × 10^-9 m

f = 3 × 10^8 m/s/ 1 × 10^-6 m

f = 3 × 10^14 Hz

Learn more: https://brainly.com/question/18415575

Answer:

NH₂O

Explanation:

Given compound:

       N₄H₈O₄

Unknown:

The empirical formula of the compound  = ?

Solution:

The empirical formula of a compound is its simplest formula. It expresses the composition of a the compound in the simplest whole ratio of atoms of the different elements present in the compound.

 For the given compound:

                                  N₄H₈O₄

  Number of moles of N = 4

                                      H = 8

                                      O = 4

 the highest common factor is 4 and we simply divide through by this number;

                                      N = 1

                                      H = 2

                                      O = 1

So, the empirical formula of compound is NH₂O