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harina [27]
3 years ago
12

When can a solar eclipse occur

Biology
2 answers:
LekaFEV [45]3 years ago
8 0

Answer: when their is a new moon

Explanation:

yuradex [85]3 years ago
8 0

Total solar eclipses happen when the Moon completely covers the Sun, and it can only take place when the Moon is near perigee, the point of the Moon's orbit closest to Earth. You can only see a total solar eclipse if you're in the path where the Moon casts its darkest shadow, the umbra.

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A certain buffer is made by mixing a weak acid HA and its conjugate base A–. When HA is present at a concentration of 0.5 mM and
MAVERICK [17]

Answer:The ratio of the concentrations of HA  and A^- when the buffer has a pH of 7.02 is 0.69

Explanation:

The dissociation constant for formic acid = K_a=1.8\times 10^{-4}

Concentration of HA= 0.5 mM

Concentration of A^-= 0.1 mM

pH = 6.16

First we have to calculate the value of K_a.

Using Henderson Hesselbach equation :

pH=pK_a+\log \frac{[A^-}{[HA]}

Now put all the given values in this expression, we get:

6.16=pK_a+\log (\frac{[0.1]}{0.5})

pK_a=6.86

To calculate the ratio of the concentrations of HA  and A^- when the buffer has a pH of 7.02.

Using Henderson Hesselbach equation :

7.02=6.86+\log \frac{[A^-]}{[HA]}

7.02=6.86+\log \frac{[A^-]}{[HA]}

\frac{[A^-]}{[HA]}=1.44

\frac{[HA]}{[A^-]}=0.69

Thus the ratio of the concentrations of HA  and A^- when the buffer has a pH of 7.02 is 0.69

7 0
3 years ago
Approximately 70-80 percent of cancers in the aging population are the result of
den301095 [7]
Cigarette smoking and environmental chemicals

Tobacco smoke and certain environmental chemicals are known carcinogens (substances that can cause cancer in living tissue). The tobacco smoke from cigarette smoking contains harmful chemicals such as hydrogen cyanide, arsenic, ammonia, benzene, and many more. In fact, from 2009 to 2013, three out of 10 cancer deaths in the U.S have been attributed to cigarette smoking or exposure to tobacco smoke. 
8 0
3 years ago
Please select the word from the list that best fits the definition
Pani-rosa [81]

Answer:

The correct answer is - active transport.

Explanation:

Active transport is the movement of a substance that crosses the cell membrane against the concentration gradient and therefore requires energy in the form of ATP. In contrast, passive transport does not require energy for the movement of a substance through the cell membrane as it moves to the concentration gradient.

This movement of molecules is towards the region of high concentration from the region of lower concentration through the cell membrane by elcectrochemical gradient or ATP.

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3 years ago
Describe the relationship between an action spectrum and an absorption spectrum. Explain why the action spectrum for photosynthe
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Answer:

An absorption spectrum illustrates the spectrum of light or electromagnetic radiation absorbed by the plant. This relies upon the molecular and cellular build-up of the plant. An action spectrum illustrates the spectrum of electromagnetic radiation most efficient for photosynthesis.  

The action spectrum of photosynthesis monitors the absorption spectrum of chlorophyll. The absorption spectrum suggests that how much of each wavelength chlorophyll will captivate, while the action potential can indicate to us about the wavelengths that are most operative for photosynthesis.  

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3 years ago
The amount of CO2 released into the air because of your own energy needs is called
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Answer:

carbon recycling

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it is released in respiration

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