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3 years ago

How many electrons are in the third energy level? 2 8 18 20

Physics

2 answers:

Alisiya [41]3 years ago

7 0

Answer:

Explanation:

plz mark brainlyest

Blababa [14]3 years ago

6 0

Answer:

B)8

Explanation:

In the first energy level you can have, at most, 2. Every energy level after that wants to have 8 electrons. Valence electrons I believe.

Hope this helps, have a nice day! (^-^)

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An expensive vacuum system can achieve a pressure as low as 1.00×10^{-7} N/m^2 at 20ºC . How many atoms are there in a cubic cen

marta [7]

Answer:

$24.70818432141\times 10^7\ atoms$

Explanation:

P = Pressure = $1\times 10^{-7}\ N/m^2$

V = Volume = 1 cm³

n = Amount of substance

N = Number of atoms

$N_A$ = Avogadro's constant = $6.022\times 10^{23}\ /mol$

R = Gas constant = 8.314 J/k mol

T = Temperature = 273.15+20 = 293.15 K

From the ideal gas law

$PV=nRT\\\Rightarrow n=\frac{PV}{RT}$

$n=\frac{N}{N_A}$

$\frac{N}{N_A}=\frac{PV}{RT}\\\Rightarrow N=N_A\times \frac{PV}{RT}\\\Rightarrow N=\frac{1\times 10^{-7}\times 1\times 10^{-6}}{8.314\times 293.15}\times 6.022\times 10^{23}\\\Rightarrow N=24708184.32141\ atoms=24.70818432141\times 10^7\ atoms$

The number of atoms is $24.70818432141\times 10^7\ atoms$

8 0

3 years ago

A cruise ship travels across a river at 25 meters per minute. If the river is 6200 meters wide, how long

EleoNora [17]

Answer:

248 minutes

Explanation:

6200/25=248

This means there is 248 25s in 6200

which means it will take 248 minutes to travel through the river

Also here's a neat trick:

The units for speed is meters/minute

The units for distance is meters

Dividing distance by speed will cancel out the meters and leave only the speed.

3 0

2 years ago

Explain how airplane wings and the wings of birds affect the air flowing over them to produce lift

d1i1m1o1n [39]

Because the air in their wings helps them fly

6 0

2 years ago

A 3-kg rock is thrown upward with a force of 200 N at a location where the local gravitational acceleration is 9.79 m/s2 . Deter

expeople1 [14]

Answer: $56.87m/s^{2}$

Explanation:

If we make an analysis of the net force $F_{net}$ of the rock that was thrown upwards, we will have the following:

$F_{net}=F_{up}-W$ (1)

Where:

$F_{up}=200N$ is the force with which the rock was thrown

$W$ is the weight of the rock

Being the weight the relation between the mass $m=3kg$ of the rock and the acceleration due gravity $g=9.79m/s^{2}$ :

$W=m.g=(3kg)(9.79m/s^{2})$ (2)

$W=29.37 N$ (3)

Substituting (3) in (1):

$F_{net}=200N-29.37 N$ (4)

$F_{net}=170.63 N$ (5) This is the net Force on the rock

On the other hand, we know this force is equal to the multiplication of the mass with the acceleration, according to Newton's 2nd Law:

$F_{net}=m.a$ (6)

Finding the acceleration $a$ :

$a=\frac{F_{net}}{m}$ (7)

$a=\frac{170.63 N}{3kg}$ (8)

Finally:

$a=56.87m/s^{2}$

3 0

2 years ago

Explain Why a flying aeroplane has more Kinetic Energy than a flying insect?

Airida [17]

Answer:

Why do insects fly so high?

Because the angle of attack is so high, a lot of momentum is transferred downward into the flow. These two features create a large amount of lift force as well as some additional drag. The important feature, however, is the lift.

Why an Aeroplane flying has kinetic

A flying aeroplane has potential energy has it flies above the ground level. And since the aeroplane is flying motion is associated with it and thus possesses kinetic energy. Hence a flying aeroplane has both potential and kinetic energ

Explanation:

5 0

3 years ago