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3 years ago

Which of the following statements is true?

Chemistry

1 answer:

lys-0071 [83]3 years ago

8 0

Answer:

Air is a good insulator because the molecules are far apart. This reduces mobility of air molecules hence conduction is difficult.

Explanation:

For other statements :

All the suns radiations are not reflected back to space because the ozone layer of the earth's atmosphere which regulates the intensity of radiations from the sun, it is transparent and porous hence heat and light rays from sun enter earth.
Work is only done by potential energy when the body is under free fall and experiencing gravitational force, but for a body moving without influence of gravity, work is done by the force applied and the distance moved by the body. This force is called a conservative force.
Total mechanical energy is given by

= Kinetic energy + Potential energy

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The work function for metallic potassium is 2.3 eV. Calculate the velocity in km/s for electrons ejected from a metallic potassi

mote1985 [20]

Answer:

932.44 km/s

Explanation:

Given that:

The work function of the magnesium = 2.3 eV

Energy in eV can be converted to energy in J as:

1 eV = 1.6022 × 10⁻¹⁹ J

So, work function = $2.3\times 1.6022\times 10^{-19}\ J=3.68506\times 10^{-19}\ J$

Using the equation for photoelectric effect as:

$E=\psi _0+\frac {1}{2}\times m\times v^2$

Also, $E=\frac {h\times c}{\lambda}$

Applying the equation as:

$\frac {h\times c}{\lambda}=\psi _0+\frac {1}{2}\times m\times v^2$

Where,

h is Plank's constant having value $6.626\times 10^{-34}\ Js$

c is the speed of light having value $3\times 10^8\ m/s$

m is the mass of electron having value $9.11\times 10^{-31}\ kg$

$\lambda$ is the wavelength of the light being bombarded

$\psi _0=Work\ function$

v is the velocity of electron

Given, $\lambda=260\ nm=260\times 10^{-9}\ m$

Thus, applying values as:

$\frac{6.626\times 10^{-34}\times 3\times 10^8}{260\times 10^{-9}}=3.68506\times 10^{-19}+\frac{1}{2}\times 9.11\times 10^{-31}\times v^2$

$3.68506\times \:10^{-19}+\frac{1}{2}\times \:9.11\times \:10^{-31}v^2=\frac{6.626\times \:10^{-34}\times \:3\times \:10^8}{260\times \:10^{-9}}$

$\frac{1}{2}\times 9.11\times 10^{-31}\times v^2=7.64538\times 10^{-19}-3.68506\times 10^{-19}$

$\frac{1}{2}\times 9.11\times 10^{-31}\times v^2=3.96032462\times 10^{-19}$

$v^2=0.869446\times 10^{12}$

v = 9.3244 × 10⁵ m/s

Also, 1 m = 0.001 km

So, v = 932.44 km/s

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3 years ago

Black and green tea have a growing body of research suggesting there are positive health benefits on because of the anti-oxidant

andrezito [222]

Keeping in mind a total ignorance of both the health benefits of these teas, and the interaction between milk and antioxidants, I believe that it is possible that milk could hinder these benefits.

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3 years ago

Galaxies are composed of many different objects. What kind ok objects make up most of the visible matter in a galaxy?

Arte-miy333 [17]

Stars make up most of the visible matter

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3 years ago

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For the following exothermic reaction, A+B⇌C+D + Heat, if the temperature is increased, the reaction will experience a shift to

Elodia [21]

(Left) I’m pretty sure

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