What is the human body's first line of defense against invading pathogens such as bacteria and viruses?

The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wave

timofeeve [1]

Explanation:

It is given that,

The electron in a hydrogen atom, originally in level n = 8, undergoes a transition to a lower level by emitting a photon of wavelength 3745 nm. It means that,

$n_i=8$

$\lambda=3745\ nm$

The amount of energy change during the transition is given by :

$\Delta E=R_H[\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}]$

And

$\dfrac{hc}{\lambda}=R_H[\dfrac{1}{n_f^2}-\dfrac{1}{n_i^2}]$

Plugging all the values we get :

$\dfrac{6.63\times 10^{-34}\times 3\times 10^8}{3745\times 10^{-9}}=2.179\times 10^{-18}[\dfrac{1}{n_f^2}-\dfrac{1}{8^2}]\\\\\dfrac{5.31\times 10^{-20}}{2.179\times 10^{-18}}=[\dfrac{1}{n_f^2}-\dfrac{1}{8^2}]\\\\0.0243=[\dfrac{1}{n_f^2}-\dfrac{1}{64}]\\\\0.0243+\dfrac{1}{64}=\dfrac{1}{n_f^2}\\\\0.039925=\dfrac{1}{n_f^2}\\\\n_f^2=25\\\\n_f=5$

So, the final level of the electron is 5.

4 0

3 years ago

6 Fe2+ (aq) + Cr2O72− (aq) + 14 H+ (aq) → 6 Fe3+ (aq) + 2 Cr3+ (aq) + 7 H2O (aq) If the titration of 23 mL of an iron(II) soluti

ratelena [41]

Answer:

1.047 M

Explanation:

The given reaction:

$6Fe^{2+}_{(aq)}+Cr_2O_7^{2-}_{(aq)}+14H^+_{(aq)}\rightarrow 6Fe^{3+}_{(aq)}+2Cr^{3+}_{(aq)}+7H_2O_{(aq)}$

For dichromate :

Molarity = 0.254 M

Volume = 15.8 mL

The conversion of mL to L is shown below:

1 mL = 10⁻³ L

Thus, volume = 15.8 ×10⁻³ L

Thus, moles of dichromate :

$Moles=0.254 \times {15.8\times 10^{-3}}\ moles$

Moles of dichromate = 0.0040132 moles

1 mole of dichromate react with 6 moles of iron(II) solution

Thus,

0.0040132 moles of dichromate react with 6 × 0.0040132 moles of iron(II) solution

Moles of iron(II) solution = 0.02408 moles

Volume = 23 mL = 0.023 L

Considering:

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

<u>Molarity = 0.02408 / 0.023 = 1.047 M</u>

7 0

3 years ago

A balloon vendor at a street fair is using a tank of helium to fill her balloons. The tank has a volume of 124.0 L and a pressur

amm1812

Answer:

She lost 50.88 moles

Explanation:

Step 1: Data given

The volume of the tank = 124.0 L

The initial pressure = 104.0 atm

The temperature = 24.0 °C = 297 K

The pressure drops to 94.0 atm

The temperature stays constant at 297 K

Step 2: Calculate the initial number of moles

p*V = n*R*T

n = (p*V)/(R*T)

⇒with p = the initial pressure = 104.0 atm

⇒with V = the initial volume = 124.0 L

⇒with n = the initial number of moles = TO BE DETERMINED

⇒with R = the gas constant = 0.08206 L*atm/mol*K

⇒ with T = the temperature= 297 K

n = (104.0*124.0)/(0.08206*297)

n = 529.14 moles

Step 3: Calculate final number of moles

p*V = n*R*T

n = (p*V)/(R*T)

⇒with p = the initial pressure = 94.0 atm

⇒with V = the initial volume = 124.0 L

⇒with n = the initial number of moles = TO BE DETERMINED

⇒with R = the gas constant = 0.08206 L*atm/mol*K

⇒ with T = the temperature= 297 K

n = (94.0*124.0)/(0.08206*297)

n = 478.26 moles

Step 4: Calculate the difference of moles

529.14 moles - 478.26 moles = 50.88 moles

She lost 50.88 moles

4 0

3 years ago

Calculate total ATP produced from a fatty acid of 32 carbons

emmasim [6.3K]

Answer:

Total number of ATP molecules generated from a 32-carbon fatty acid = 206 ATP molecules

Explanation:

A 32 carbon fatty acid which undergoes complete beta-oxidation assuming that the fatty acid is fully saturated will pass through the beta-oxidation cycle 14 times to produce the following:

15 molecules of acetylCoA, 14 molecules of FADH₂, and 14 molecules of NADH.

Each of the 15 acetylCoA molecules can be further oxidized in the citric acid cycle to yield the following: 15 × 3 NADH; 15 × 1 FADH₂, and 15 ATP molecules from the substrate level phosphorylation occuring at the succinylCoA synthetase catalyzed-reaction.

Total FADH₂ produced = 15 + 14 = 29 molecules of FADH₂

Total NADH produced = 45 + 14 = 59 molecules of NADH

The FADH₂ and NADH will each donate a pair of electrons to the electron transfer flavoprotein and mitochondrial NADH dehydrogenase respectively of the electron transport chain, and about 1.5 and 2.5 molecules of ATP are generated respectively when these electrons are transfered to molecular oxygen.

Thus, number of molecules of ATP generated by 29 molecules of FADH₂ = 1.5 × 29 = 43.5 molecules of ATP.

Number of molecules of ATP generated by 59 molecules of NADH = 2.5 × 59 = 147.5

Sum of ATP generated from FADH₂ and NADH = 43.5 + 147.5 = 191 ATP molecules

Total number of ATP molecules generated = 191 + 15 = 206 ATP molecules

Total number of ATP molecules generated from a 32-carbon fatty acid = 206 ATP molecules

7 0

3 years ago

MULTIPLE CHOICE QUESTION

zubka84 [21]

Answer:

This question will be answered based on general understanding of how a controlled experiment should be:

The answer is: We must make sure we are testing/changing only one variable, and controling others

Explanation:

A controlled experiment is an experiment in which the independent variable is changed for a particular group called the EXPERIMENTAL group and unchanged for another group called the CONTROL group.

In a controlled experiment, only one variable should be tested while the others should be kept constant in order to have an effective result or outcome. This is the case in this question, the type of music or soil should be unchanged for each plant because the experimenter must make sure that he/she is testing/changing only one variable, and controling others.

4 0

3 years ago