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OverLord2011 [107]
3 years ago
5

A farmer lost most of his crops last year because of insects. This year he decided to use pesticide to kill the insects. However

, some of the insects survived the pesticide and have reproducedThe new population of insects is not affected by the pesticide. After several generations, more insects are born that survive the pesticide. What process explains the change in insect population?
A. natural selection

B. genetic engineering

C. extinction

D. artificial selection
Chemistry
1 answer:
Dominik [7]3 years ago
6 0
The answer would be natural selection I believe
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Answer:

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2 years ago
You have discovered an element that is a poor conductor of electricity, has a low melting point, and is a gas at room temperatur
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AHHH ITS B SORRY I ACTUALLY KNOE THIS
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3 years ago
Write the isotopic symbol for the following (show your work) a) An isotope of iodine whose atoms have 78 neutrons b) An isotope
morpeh [17]

<u>Answer:</u>

<u>For a:</u> The isotopic representation of iodine is _{53}^{131}\textrm{I}

<u>For b:</u> The isotopic representation of cesium is _{55}^{137}\textrm{Cs}

<u>For c:</u> The isotopic representation of strontium is _{38}^{52}\textrm{Sr}

<u>Explanation:</u>

The isotopic representation of an atom is: _Z^A\textrm{X}

where,

Z = Atomic number of the atom

A = Mass number of the atom

X = Symbol of the atom

  • <u>For a:</u>

We are given:

Number of neutrons = 78

Atomic number of iodine = 53 = Number of protons

Mass number = 53 + 78 = 131

Thus, the isotopic representation of iodine is _{53}^{131}\textrm{I}

  • <u>For b:</u>

We are given:

Number of neutrons = 82

Atomic number of cesium = 55 = Number of protons

Mass number = 55 + 82 = 137

Thus, the isotopic representation of cesium is _{55}^{137}\textrm{Cs}

  • <u>For c:</u>

We are given:

Number of neutrons = 52

Atomic number of strontium = 38 = Number of protons

Mass number = 38 + 52 = 90

Thus, the isotopic representation of strontium is _{38}^{52}\textrm{Sr}

3 0
3 years ago
Which of the following best defines molar mass?
coldgirl [10]

Answer:

D. the mass of one mole of a substance

Explanation:

The molar mass of a substance is the mass in grams of one mole of the substance.

  • For an element, the molar mass is the relative atoms mass expressed in grams.
  • For example 23g of Na, 40g of oxygen
  • For compounds, molar mass is the gram -formula or gram - molecular weight.
  • This is determined by the addition of its component atomic masses and then expressed in grams.
7 0
3 years ago
A bottle of coke is 250.0 mL. What is the volume in cubic centimeters?
hoa [83]

Answer:

The volume in cubic centimeters is 250

Explanation:

The rule of three or is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them.

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other (or when one magnitude decreases, so does the other), the direct rule of three must be applied. To solve a direct rule of three, the following formula must be followed:

a ⇒ b

c ⇒ x

So:

x=\frac{c*b}{a}

The direct rule of three is the rule applied in this case where there is a change of units. To perform this conversion of units, you must first know that 1 mL = 1 cubic centimeters. So, if 1 cubic centimeters is 1 mL, how many cubic centimeters equals 250 mL?

cubic centimeters=\frac{250 mL*1 cubic centimeters }{1 mL}

cubic centimeters= 250

<u><em>The volume in cubic centimeters is 250</em></u>

3 0
3 years ago
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