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3 years ago

The observed brightness of a star depends on which factors?

Chemistry

1 answer:

dimulka [17.4K]3 years ago

6 0

Answer:

b..............

Explanation:

......

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How is the electronegativity trend related to the first ionization energy trend?

nataly862011 [7]

D. Electronegativity and first ionization energy both increase as you

move up the periodic table.

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3 years ago

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Which structure assist with cell ur respiration?

Alexandra [31]

Answer:

Mitochondria

Explanation:

Mitochondria are organelles whose membranes are specialized for aerobic respiration.

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3 years ago

In the periodic table, the period number indicates

sergey [27]

Answer: option B. The number of the outer most energy level for elements in that period

Explanation:

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3 years ago

A laser pulse with wavelength 525 nm contains 4.40 mj of energy. How many photons are in the laser pulse

Alexandra [31]

The laser pulse in this question has a wavelength of $\lambda=524 nm=525\times 10^{-9}m$ . To solve this problem, we first have to calculate the energy of a single photon in the laser pulse. The equation for calculating the energy of a single photon of an electromagnetic wave is $E=\frac{hc}{\lambda}$ where $c$ is the speed of light, $h$ is planks constant and $\lambda$ is the wave length of the photons.

For this problem, $c=3.0\times 10^8m/s$ , $h=6.63\times10^{-34}J.s$ and $\lambda=525\times 10^{-9}m$ . We use these values to calculate the energy of the photon as shown below,

$E=\frac{hc}{\lambda} \\E=\frac{(6.63\times 10^{32}Js)\times(3.0\times10^8m/s)}{525\times 10^{-9}m} \\E=3.79\times 10 ^{-19}J.$

Now that we know the energy for a single photon, we will divide the total energy given by the energy of one photon to get the number of photons in the pulse. The number of photons $n$ is calculated as shown below,

$n=\frac{4.4\times 10^{-3}J}{3.79\times10^{-19}J} =1.16\times 10^{16}$ . There are $1.16\times 10^{16}$ photons.

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3 years ago

In an exothermic reaction, energy may be released to the surroundings in the form of?

djverab [1.8K]

Answer:

All of the above

Explanation:

Exothermic reactions release energy usually in the form of heat, but also in a form of light (e.g. a spark, flame, or flash), electricity (e.g. a battery), or sound (e.g. explosion heard when burning hydrogen)

7 0

4 years ago