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3 years ago

1. Classify the following matter as a pure substance or a mixture. Potassium

Chemistry

1 answer:

dlinn [17]3 years ago

4 0

Pure substance, basically, it’s on the periodic table.

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How many grams is in a 5 pound sample? express your answer in scientific notation with four significant figures. (1 pound = 453.

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3 years ago

Living things are made mostly of what four main elements

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3 years ago

A light source of wavelength, l, illuminates a metal and ejects photoelectrons with a maximum kinetic energy of 1 eV. A second l

madreJ [45]

Explanation:

From first source, kinetic energy ( $K.E_{1}$ ) ejected is 1 eV and wavelength of light is $\lambda$ .

From second source, kinetic energy ( $K.E_{2}$ ) ejected is 4 eV and wavelength of light is $\frac{\lambda}{2}$ .

Relation between work function, wavelength, and kinetic energy is as follows.

K.E = $\frac{hc}{\lambda} - \phi$

where, h = Plank's constant = $6.63 \times 10^{-34}$ J.s

c = speed of light = $3 \times 10^{8}$ m/s

Also, it is known that 1 eV = $1.6 \times 10^{-19}$ J

Therefore, substituting the values in the above formula as follows.

From first source,

$K.E_{1}$ = $\frac{hc}{\lambda} - \phi$

1 eV = $1.6 \times 10^{-19} J = \frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{\lambda} - \phi$

$1.6 \times 10^{-19} J = \frac{1.98 \times 10^{-25} J.m}{\lambda} - \phi$ ........... (1)

From second source,

$K.E_{2}$ = $\frac{hc}{\lambda} - \phi$

$4 \times 1.6 \times 10^{-19} J = \frac{6.63 \times 10^{-34} \times 3 \times 10^{8}}{\frac{\lambda}{2}} - \phi$

$6.4 \times 10^{-19} J = \frac{2 \times 1.98 \times 10^{-25} J.m}{\lambda} - \phi$ ........... (2)

Now, divide equation (2) by 2. Therefore, it will become

${6.4 \times 10^{-19}J}{2} = \frac{2 \times 1.98 \times 10^{-25} J.m}{2\lambda} - \frac{\phi}{2}$

$3.2 \times 10^{-19}J = \frac{1.98 \times 10^{-25} J.m}{\lambda} - \frac{\phi}{2}$ ......... (3)

Now, subtract equation (3) from equation (1), we get the following.

$1.6 \times 10^{-19} = \frac{\phi}{2}$

$\phi$ = $3.2 \times 10^{-19}$

= 2 eV

Thus, we can conclude that work function of the metal is 2 eV.

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4 years ago

how is the process of neutralization reaction like the procesd of mixing white and black paints to get gray

devlian [24]

Answer:

Acid neutralizes base to form salt and water while white colour neutralizes black colour to form grey colour.

Explanation:

Neutralization is simply the process whereby an acid and a base are mixed to produce salt and water. Now, this reaction also involves the mixing of the hydrogen ions of the acid and hydroxide ions of the base to form the salt and water. It is similar to mixing 2 paints to form another colour in that in the neutralization reaction 2 compounds are mixed to neutralize each other to form another compound while in mixing black and white to form grey the two colors are mixed together and thereby neutralized to form another colour which is grey.

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3 years ago