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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
You might be interested in
Mercury, which is sometimes used in thermometers, has a density of 13.534 g/ml at room temperature. what volume of mercury conta
Sergeu [11.5K]
D - density: 13,534 g/ml
m - mass: 10g
V - volume: ??
_____________
d = m/V
V = m/d
V = 10/13,534
V = 0,7389 ml

:•)
6 0
3 years ago
A 30.7 g sample of Strontium nitrate, Sr(NO3)2•nH2O, is heated to a constant mass of 22.9 g. Calculate the hydration number.
Elodia [21]

Answer:

  • <em>Hydration number:</em> 4

Explanation:

<u>1) Mass of water in the hydrated compound</u>

Mass of water = Mass of the hydrated sample - mass of the dehydrated compound

Mass of water = 30.7 g - 22.9 g = 7.8 g

<u>2) Number of moles of water</u>

  • Number of moles = mass in grams / molar mass

  • molar mass of H₂O = 2×1.008 g/mol + 15.999 g*mol = 18.015 g/mol

  • Number of moles of H₂O = 7.9 g / 18.015 g/mol = 0.439 mol

<u>3) Number of moles of Strontium nitrate dehydrated, Sr (NO₃)₂</u>

  • The mass of strontium nitrate dehydrated is the constant mass obtained after heating = 22.9 g

  • Molar mass of Sr (NO₃)₂ :  211.63 g/mol (you can obtain it from a internet or calculate using the atomic masses of each element from a periodic table).

  • Number of moles of Sr (NO₃)₂ = 22.9 g / 211.63 g/mol =  0.108 mol

<u>4) Ratio</u>

  • 0.439 mol H₂O / 0.108 mol Sr(NO₃)₂ ≈  4 mol H₂O : 1 mol Sr (NO₃)₂

Which means that the hydration number is 4.

4 0
3 years ago
Read 2 more answers
What is the molarity (M) of the following solutions?
Dennis_Churaev [7]

Answer:

The molarity (M) of the following solutions are :

A. M = 0.88 M

B. M = 0.76 M

Explanation:

A. Molarity (M) of 19.2 g of Al(OH)3 dissolved in water to make 280 mL of solution.

Molar mass of Al(OH)3 = Mass of Al + 3(mass of O + mass of H)

                                      = 27 + 3(16 + 1)

                                      = 27 + 3(17) = 27 + 51

                                      = 78 g/mole

Al(OH)_3 = 78 g/mole

Given mass= 19.2 g/mole

Mole = \frac{Given\ mass}{Molar\ mass}

Mole = \frac{19.2}{78}

Moles = 0.246

Molarity = \frac{Moles\ of\ solute}{Volume\ of\ solution(L)}

Volume = 280 mL = 0.280 L

Molarity = \frac{0.246}{0.280)}

Molarity  = 0.879 M

Molarity  = 0.88 M

B .The molarity (M) of a 2.6 L solution made with 235.9 g of KBr​

Molar mass of KBr = 119 g/mole

Given mass = 235.9 g

Mole = \frac{235.9}{119}

Moles = 1.98

Volume = 2.6 L

Molarity = \frac{Moles\ of\ solute}{Volume\ of\ solution(L)}

Molarity = \frac{1.98}{2.6)}

Molarity = 0.762 M

Molarity = 0.76 M

4 0
3 years ago
I need help please! I will mark brainliest
Fittoniya [83]

Answer: I think it's C

Explanation: I hope this helps (Sorry if it doesn't)

8 0
1 year ago
What is the most likely type of bond formed between element x and iodine?
Tanzania [10]
The most likely bond between element X and Iodine would be an ionic, or electrovalent, bond. Iodine has seven electrons in its outer shell, also known as the valence shell. To become perfectly stable, it needs only a single electron from another element. Hence no sharing of electron takes place (usually), which is the condition required for it to be covalent bonding. Hence it's most likely an ionic bonding/
5 0
3 years ago
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