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MariettaO [177]

3 years ago

15

Plate tectonics is helpful in explaining many things we observe on Earth. Which of the following is the best example of somethin

g that results from tectonic plate movement?

1 answer:

Vsevolod [243]3 years ago

3 0

Answer: Seafloor spreading causes changes in coastlines

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An atom of helium has a radius of 31. pm and the average orbital speed of the electrons in it is about 4.4x 10 m/s Calculate the

otez555 [7]

The question is incomplete, here is the complete question:

An atom of helium has a radius of 31. pm and the average orbital speed of the electrons in it is about $4.4\times 10^6m/s$ . Calculate the least possible uncertainty in a measurement of the speed of an electron in an atom of helium. Write your answer as a percentage of the average speed, and round it to 2 significant digits

<u>Answer:</u> The percentage of average speed is 41 %

<u>Explanation:</u>

We are given:

Radius of helium atom = 31 pm = $31\times 10^{-12}m$ (Conversion factor: $1m=10^{12}pm$ )

So, diameter of helium atom = $(2\times r)=(2\times 31\times 10^{-12})=64\times 10^{-12}m$

The diameter of the atom will be equal to the uncertainty in position.

The equation representing Heisenberg's uncertainty principle follows:

$\Delta x.\Delta p=\frac{h}{2\pi}$

where,

$\Delta x$ = uncertainty in position = d = $64\times 10^{-12}m$

$\Delta p$ = uncertainty in momentum = $m\Delta v$

m = mass of electron = $9.1095\times 10^{-31}kg$

h = Planck's constant = $6.627\times 10^{-34}kgm^2/s^2$

Putting values in above equation, we get:

$64\times 10^{-12}m\times 9.1095\times 10^{-31}kg\times \Delta v=\frac{6.627\times 10^{-34}kgm^2/s}{2\times 3.14}\\\\\Delta v=\frac{6.627\times 10^{-34}kgm^2/s^2}{2\times 3.14\times 64\times 10^{-12}m\times 9.1095\times 10^{-31}kg}=1.81\times 10^6m/s$

To calculate the percentage of average speed, we use the equation:

$\text{Percentage of the average speed}=\frac{\text{Uncertainty in velocity}}{\text{Average orbital speed}}\times 100$

We are given:

Average orbital speed = $4.4\times 10^6m/s$

Putting values in above equation, we get:

$\text{Percentage of the average speed}=\frac{1.81\times 10^6m/s}{4.4\times 10^6m/s}\times 100\\\\\text{Percentage of the average speed}=41.\%$

Hence, the percentage of average speed is 41 %

3 0

4 years ago

A sample of neon occupies a volume of 461 mL at 1 atm and 273 K. What will be the volume of the neon when the pressure is reduce

Softa [21]

Answer:

0.501 L

Explanation:

To solve this problem we will use Boyle,s Law. According to this law "The volume of given amount of gas is inversely proportional to applied pressure at constant temperature".

V∝ 1/P

V= K/P

VP=K

Here the K is proportionality constant.

so,

P1V1 = P2V2

P= pressure

V= volume

Given data:

P1= 1 atm

V1= 461 mL

P2= 0.92 atm

V2= ? (L)

To solve this problem we have to convert the mL into L first.

1 L = 1000 mL

461/1000= 0.461 L

Now we will put the values in the equation,

P1V1 = P2V2

V2= P1V1/ P2

V2= 1 atm × 0.461 L / 0.92 atm

V2= 0.501 L

4 0

4 years ago

1.How many mL of 0.523 M HBr are needed to dissolve 8.60 g of CaCO3?

prohojiy [21]

Answer:

The answer to your question is:

Explanation:

1.-

HBr = 0.523 M V = ?

CaCO3 = 8.6 g

2HBr(aq) + CaCO₃(s) ⇒ CaBr₂(aq) + H₂O(l) + CO₂(g)

MW CaCO₃ = 40 + 12 + 48 = 100 g

MW HBr = 80 + 1 = 81 g

Molarity = moles / volume

100 g of CaCO₃ ---------------- 1 mol

8.6 g ---------------- x

x = (8.6 x 1) / 100

x = 0.086 moles

2 moles of HBr ----------------- 1 mol of CaCO₃

x ----------------- 0.086 moles

x = (0.086 x 2) / 1 = 0.172 moles of HBr

Volume = moles / molarity

Volume = 0.172/ 0.523 = 0.323 l or 323 ml of HBr

2.-

V = ? ml NaOH 0.487 M

V = 101 ml of 0.628 M MnSO₄

MnSO₄(aq) + 2NaOH(aq) ⇒ Mn(OH)₂(s) + Na₂SO₄(aq)

MW MnSO₄ = 55 g

MW NaOH = NaOH = 40 g

Moles = Molarity x volume

Moles = (0.628) x (0.101)

Moles = 0.065 moles of MnSO₄

1 mol of MnSO₄ ------------------ 2 moles of NaOH

0.065 ----------------- x

x = (0.065x 2) / 1

x = 0.131 moles of NaOH

Volume = moles / molarity

Volume = 0.131 / 0.487

Volume = 0.268 l or 268 ml of NaOH

4 0

3 years ago

What is "Scarcity" <br><img src="https://tex.z-dn.net/?f=." id="TexFormula1" title="." alt="." align="absmiddle" class="latex-fo

Lana71 [14]

Explanation:

I don't know sorry ok I have some work so I m sorry

4 0

3 years ago

Read 2 more answers

Which is equal to a cubic centimeter <br><br> 1. cg <br> 2. mL<br> 3. Kg<br> 4. mm

liq [111]

Answer:

1 ml

Explanation:

formula multiply the volume value by one

6 0

3 years ago