Which of these is a biotic factor? <br> A) topography <br> B) soil <br> C )air <br> D)bacteria

Bacteria vary somewhat in size, but a diameter of 2.9 μm is not unusual.

Sedbober [7]

Answer:

a) 6.4 x 10^-12 cm^3

b) 17 x 10^-6 mm^2

Explanation

a). The shape is assumed to be spherical The volume = volume of a sphere = \frac{4}{3} \pi r^3

3

4

πr

3

V = \frac{4}{3}*3.142* 1.15^3

3

4

∗3.142∗1.15

3

= 6.3715 μm^3

1 μm^3 = 10^-12 cm^3

6.3715 μm^3 = 6.3715 x 10^-12 cm^3

==> 6.4 x 10^-12 cm^3

8 0

2 years ago

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PLS HELP ASAP!!! <br> I don’t understand this at all

Mnenie [13.5K]

Answer:

The part that completes the nuclear equation is:

$^{221}_{87}Fr$

Explanation:

<h2>A) Preliminar explanation</h2>

The <em>nuclear equation</em> represents a nuclear reaction: the change of the nucleus of an atom.

The given equation represents an actinium atom releasing an alpha particle.

This is the meaning of each part of the equation:

Ac is the chemical symbol of actinium
The superscript to the left of the chemical symbol is the mass number of the atom (number of protons plus number of neutrons). The mass number is 225.
The subscript to the left of the chemical symbol is the atomic number of the atom (number of protons). The atomic number is 89.

$^4_2He$ is the symbol of the alpha particle. It is an atom of helium
The mass number is 4
The atomic number is 2

<h2>B) Solution</h2>

To <em>complete the nuclear equation </em>you must do two balances: mass number balance and atomic number balance.

<u>i) Mass number balance</u>

225 = A + 4 ⇒ A = 225 - 4 = 221

<u>ii) Atomic number balance</u>

89 = Z + 2 ⇒ Z = 89 - 2 = 87

Therefore, the mass number of the unknown atom is 221, and the atomic number is 87.

From a periodic table, the element with atomic number 87 is francium, Fr.

Now, you have the chemical symbol, the atomic number, and the mass number of the unknown atom, which lets you to write the atom that completes the <em>nuclear equation</em>.

$^{221}_{87}Fr$

7 0

3 years ago

Light of wavelength 550 nm comes into a thin slit and produces a diffraction pattern on a board 8.0 m away. The first minimum da

FrozenT [24]

Answer:

Width of the slit will be equal to 1.47 mm

Explanation:

We have given wavelength of the light $\lambda =550nm=550\times 10^{-9}m$

Distance D = 8 m

Distance between first minimum dark fringe and the central maximum is 2 mm

So $x=3\times 10^{-3}m$

We have to find the width of the slit

For the first order wavelength is equal to $\lambda =\frac{x}{D}\times a$ , here a width of slit

So $a=\frac{\lambda D}{x}=\frac{550\times 10^{-9}\times 8}{3\times 10^{-3}}=1466.666\times 10^{-6}=1.47mm$

So width of the slit will be equal to 1.47 mm

5 0

3 years ago

The greenhouse effect presentation summarized?

emmainna [20.7K]

Answer:

What is the greenhouse effect?

The greenhouse effect is the way in which heat is trapped close to Earth's surface by “greenhouse gases.”

Explanation:

These heat-trapping gases can be thought of as a blanket wrapped around Earth, keeping the planet toastier than it would be without them. Greenhouse gases include carbon dioxide, methane, nitrous oxides, and water vapor. (Water vapor, which responds physically or chemically to changes in temperature, is called a "feedback.") Scientists have determined that carbon dioxide's warming effect helps stabilize Earth's atmosphere. Remove carbon dioxide, and the terrestrial greenhouse effect would collapse. Without carbon dioxide, Earth's surface would be some 33°C (59°F) cooler.

Credit: NASA

I hope this helps, if it doesn't then just message me and ill be more than happy to help :)

8 0

2 years ago

Which best describes a nonmagnetic material?

Natali [406]

Material that is not attracted to metal

3 0

3 years ago

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Which of these is a biotic factor? A) topography B) soil C )air D)bacteria