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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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When Xavier places his hands near a light bulb, he notices that certain areas around the light bulb are warmer than others. Whic
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The area directly above the light bulb is warmest because of convection.

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3 years ago
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What is the solubility of La(IO₃)₃ in a solution that contains 0.100 M IO₃⁻ ions? (Ksp of La(IO₃)₃ is 7.5 × 10⁻¹²)
love history [14]

<u>Solution and Explanation:</u>

[La3+] = 0.1 M

<u>At the equilibrium: </u>

La(IO3)3 <---->     La3+     +         3 IO3-  

                    0.1 +s             3s      

\mathrm{Ksp}=[\mathrm{La} 3+][\mathrm{IO} 3-]^{\wedge} 3

7.5 * 10^{\wedge}-12=(0.1+s) *(3 s)^{\wedge} 3

Since Ksp is small, s can be ignored as compared to the 0.1

The above shown expression thus becomes:

7.5 * 10 \wedge-12=(0.1) *(3 s) \wedge 3

7.5 * 10^{\wedge}-12=0.1 * 27(\mathrm{s})^{\wedge} 3

s=1.406 * 10^{\wedge}-4 \mathrm{M}

<u>Answer: 1.4*10^-4 M </u>

3 0
3 years ago
We know that for a given reaction when the temperature increases from 100 k to 200 k the rate constant doubles. What is the acti
Alenkasestr [34]

Answer:

The activation energy of the reaction is 1.152 kJ/mol.

Explanation:

Activation energy is the minimum amount which is absorbed by the reactant molecules to undergo chemical reaction.

Initial temperature of reaction = T_1=100 K

Final temperature of reaction = T_2=200 K

Initial rate of the reaction at 100 k = K_1=k

Final rate of the reaction at 200 k = K_2=2k

Activation energy is calculated from the formula:

\log\frac{K_2}{K_1}=\frac{E_a}{2.303\times R}(\frac{T_2-T_1}{T_1T_2})

R = Universal gas constant = 8.314 J/ K mol

\log\frac{2k}{k}=\frac{E_a}{2.303\times 8.314 J/K mol}(\frac{200 K-100K}{200 K\times 100K})

E_a=1,152.772 J/mol=1.152 kJ/mol

5 0
3 years ago
Is oxygen an element or a compound? Explain.
Margarita [4]
<h3><u>Answer;</u></h3>

Element

<h3><u>Explanation;</u></h3>

Oxygen is an element and not a compound.

Elements are substances that can't be split into simpler substances by chemical means. They include, hydrogen, oxygen, sodium, etc.

Compounds are substances that are made up of two or more elements e.g. water is a compound, since it is made up of oxygen and hydrogen element. Compounds unlike elements can be split into simpler substances by chemical means.

3 0
3 years ago
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An impure sample of benzoic acid (C 6H 5COOH, 122.12 g/mol) is titrated with 0.2099 M NaOH. A 1.021-g sample requires 35.73 mL o
Finger [1]

Answer:

The percent by mass of benzoic acid = 89.7 %

Explanation:

Step 1: Data given

Molarity of NaOH = 0.2099 M

Mass of the sample = 1.021 grams

Volume of NaOH = 35.73 mL = 0.03573 L

Step 2: The balanced equation

C6H5COOH(aq) + NaOH(aq) → NaC6H5COO(aq) + H2O(l)

Step 3: Calculate moles NaOH

Moles NaOH = molarity NaOH * volume NaOH

Moles NaOH = 0.2099 * 0.03573 L

Moles NaOH = 0.00750 moles

Step 3: Calculate moles benzoic acid

From your balanced equation - benzoic acid reacts in 1:1 molar ratio with NaOH  

The sample must have contained 0.00750 moles benzoic acid  

Mass benzoic acid in 0.00750 moles  = 0.00750 * 122.12 = 0.9159 g benzoic acid  

Mass % acid in sample =  0.9159/1.021 * 100 = 89.7% purity.

The percent by mass of benzoic acid = 89.7 %

5 0
3 years ago
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