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insens350 [35]
2 years ago
11

Jared sprayed a pesticide on his garden three times. The first time, many insects died. The second time fewer insects died. The

last time very few insects died. What impact did the insecticide have on the species of insects? A. All of the insects were resistant to the insecticide. B. The species became less resistant to the insecticide. C. The species became more resistant to the insecticide. D. None of the insects were resistant to the insecticide.
Chemistry
2 answers:
olga_2 [115]2 years ago
5 0

Answer:

C. The species became more resistant to the insecticide.

Explanation:

The more of something you receive, the more immune you are to it. For example, every year, many people get a flu shot. Flu shots contain small amounts of the flu, and it is inserted into your blood stream so that you may become more immune to the disease when it comes around. The same happens for many living things, including insects.

Rina8888 [55]2 years ago
5 0

Answer:

C. The species became more resistant to the insecticide.

Explanation:

The insects that were resistant to the pesticide survived and reproduced. They passed on the resistance to their offspring. So, the species became more resistant to the insecticide over time.  Though some insects died, the species as a whole was able to survive. (got it right on study island)

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Mnenie [13.5K]

Answer:

I’m pretty sure it’s Lions sleeping after a big meal

Explanation:

8 0
2 years ago
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The Sun is a main sequence star. During the last stage of its life cycle, it will become a white dwarf. It will shrink in size,
dangina [55]
The one that is tiny and white. 
3 0
2 years ago
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A 0.15 m solution of chloroacetic acid has a ph of 1.86. What is the value of ka for this acid?
dem82 [27]

Answer: 1.67\times 10^{-3}

Explanation:

ClCH_2COOH\rightarrow ClCH_2COO^-+H^+

   cM              0             0

c-c\alpha        c\alpha          c\alpha  

So dissociation constant will be:

K_a=\frac{(c\alpha)^{2}}{c-c\alpha}

Given:  c = 0.15 M

pH = 1.86

K_a = ?

Putting in the values we get:

Also pH=-log[H^+]

1.86=-log[H^+]

[H^+]=0.01

[H^+]=c\times \alpha

0.01=0.15\times \alpha

\alpha=0.06

As [H^+]=[ClCH_2COO^-]=0.01

K_a=\frac{(0.01)^2}{(0.15-0.15\times 0.06)}

K_a=1.67\times 10^{-3]

Thus the vale of K_a for the acid is 1.67\times 10^{-3}

4 0
2 years ago
Consider the following system at equilibrium where H° = -87.9 kJ, and Kc = 83.3, at 500 K. PCl3(g) + Cl2(g) PCl5(g) If the VOLUM
7nadin3 [17]

Answer:

The value of Kc C. remains the same.

The value of Qc C. is less than Kc.

The reaction must: A. run in the forward direction to reestablish equilibrium

The number of moles of Cl2 will  B. decrease.

Explanation:

Le Chatelier's Principle states that if a system in equilibrium undergoes a change in conditions, it will move to a new position in order to counteract the effect that disturbed it and recover the state of equilibrium.

A decrease in volume causes the system to evolve in the direction in which there is less volume, that is, where the number of gaseous moles is less.

But temperature is the only variable that, in addition to influencing equilibrium, modifies the value of the constant Kc. So if the volume of the equilibrium system is suddenly decreased at constant temperature: <u><em>The value of Kc remains the same.</em></u>

<u><em> </em></u>As mentioned, if the volume of an equilibrium gas system decreases, the system moves to where there are fewer moles. In this case, being:

PCl₃(g) + Cl₂(g) ⇔ PCl₅(g)

The equilibrium in this case then shifts to the right because there is 1 mole in the term on the right, compared to the two moles on the left. So, <u><em>The reaction must: A. run in the forward direction to reestablish equilibrium</em></u>.

By decreasing the volume, and so that Kc remains constant, being:

Kc=\frac{[PCl_{5} ]}{[PCl_{3}]*[Cl_{2}  ]}=\frac{\frac{nPCl_{5} }{Volume} }{\frac{nPCl_{3}}{Volume}*\frac{nCl_{2} }{Volume}  } =\frac{nPCl_{5}}{nPCl_{3}*nCl_{2}} *Volume

 where nPCl₅, nPCl₃ and nCl₂ are the moles in equilibrium of PCl₅, PCl₃ and Cl₂

so,  the number of moles of Cl₂ should decrease.<u><em>The number of moles of Cl2 will  B. decrease.</em></u>

If the reaction quotient is less than the equilibrium constant, Qc <Kc, the system will evolve to the right, the direct reaction prevailing, to increase the concentration of products. So in this case, if the reaction moves to the right, <em><u>the value of Qc C. is less than Kc.</u></em>

3 0
2 years ago
What mass of carbon dioxide could be made from 100 tonnes of calcium carbonate?
MA_775_DIABLO [31]
Total mass of CaCO3 = 40 amu of Ca + 12amu of C + 16×3 amu of oxygen = 100amu of CaCO3




i.e 100 tonnes of CaCO3 .


mass of CO2 = 12amu of C + 2× 16amu of O = 44 amu of CO2




mass % of CO2 in CaCO3 = (44/100)×100 =44%


i.e
44% of 100 tonnes is CO2.
=44 tonnes of CO2.

therefore, 44% of CO2 is present in CaCO3.








3 0
2 years ago
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