2 years ago

How was Mendeleev first periodic table like the periodic table today

Physics

1 answer:

Mila [183]2 years ago

5 0

Answer:

He began organizing the known elements according to their atomic weights and chemical properties.

Explanation:

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Before you go.. Is there something I could've said to make your heart beat better?

Zinaida [17]

Answer:

no ... hahahha! but I know every boys wait for the day when their heart beat is faster than normal ever in life

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2 years ago

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The maximum wavelength that an electromagnetic wave can have and still eject electrons from a metal surface is 459 nm. What is t

spin [16.1K]

Answer:

2.7067 eV

Explanation:

h = Planck's constant = $6.626\times 10^{-34}\ m^2kg/s$

c = Speed of light = $3\times 10^8\ m/s$

$\lambda_0$ = Threshold wavelength = 459 nm

Work function is given by

$W_0=\frac{hc}{\lambda_0}\\\Rightarrow W_0=\frac{6.626\times 10^{-34}\times 3\times 10^8}{459\times 10^{-9}}\\\Rightarrow W_0=4.33072\times 10^{-19}\ J$

Converting to eV

$1\ J=\frac{1}{1.6\times 10^{-19}}\ eV$

$4.33072\times 10^{-19}\ J=4.33072\times 10^{-19}\times \frac{1}{1.6\times 10^{-19}}\ eV=2.7067\ eV$

The work function W0 of this metal is 2.7067 eV

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3 years ago

Please help me with my quiz

Oduvanchick [21]

Answer:

matter: A

data: E

variable: C

Controlled: D

Physical: B

Explanation:

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2 years ago

A new roller coaster contains a loop-the-loop in which the car and rider are completely upside down. If the radius of the loop i

Mila [183]

Answer:

11.4 m/s

Explanation:

The expression for the Centripetal acceleration is :

$a=\frac{v^2}{R}$

Where, a is the accleration

v is the velocity around circumference of circle

R is radius of circle

In the given question,

a = g = Acceleration due to gravity as the car is at top = $9.81\ m/s^2$

v = ?

R = 13.2 m

So,

$9.81=\frac{v^2}{13.2}$

$v^2=9.81\times {13.2}$

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3 years ago

a 70 kg desk sits on the floor motionless If gravity is pulling it with an acceleration of 9.8 m/s/s how much force is gravity e

adell [148]

Since force is mass*acceleration,

F = 70kg * 9.8 m/s

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3 years ago