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Ainat [17]
3 years ago
13

What is the first way in which biology researchers present the results of their latest research?

Chemistry
1 answer:
antoniya [11.8K]3 years ago
5 0
Almost always, the first way in which biology researchers present the results of their latest research is to discuss the results of previous research that they want to build off of. 
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In this forest, trees block much of the sunlight from reaching the ground. The branches of trees grow up and out to reach as muc
lions [1.4K]
<span>This example represents the challenge of survival of the fittest. In this situation, the trees have a distinct advantage due to their above average height. This puts them in the best position to gain the resources that they need to survive, most notably, the sun. The smaller plants, however, do not have this advantage, and lose out to the trees.</span>
8 0
3 years ago
Which would be most suitable for measuring 2.7 mL of ethanol for addition to a reaction with acidified dichromate?
pochemuha

Answer : The correct option is, (C) 10-mL volumeric pipet.

Explanation :

Graduated cylinder : It is a measuring cylinder that is used to measure the volume of a liquid. It has a narrow cylindrical shape. The marked line drawn on the graduated cylinder shows the amount of liquid that has been measured.

Pipet : It is a type of laboratory equipment that is used to measure the volume of a liquid. It is small glass tube and the marked line drawn on the pipet. It is used to accurately measure and transfer of volume of liquid from one container to another.

Volumetric flask : It is a type of laboratory tool that is also used for measuring the volume of liquid. It is used to make up a solution to a known volume. It measure volumes much more precisely than beakers.

Beaker : It is a type of laboratory equipment that has cylindrical shape and it is used for the mixing, stirring, and heating of chemicals.

As per question, we conclude that the pipet is most precise than other devices because in pipet the marking lines are more accurate. Thus, it can be used to measure volume to precision.

Hence, the correct option is, (C) 10-mL volumeric pipet.

8 0
3 years ago
Which of the following contribute(s) to most of the mass of an atom?
xenn [34]

Answer:

1.

B) protons and newtrons

2.

D)

3.

C)

4.

A)

6 0
3 years ago
Suppose of copper(II) acetate is dissolved in of a aqueous solution of sodium chromate. Calculate the final molarity of acetate
uranmaximum [27]

Answer:

0.0714 M for the given variables

Explanation:

The question is missing some data, but one of the original questions regarding this problem provides the following data:

Mass of copper(II) acetate: m_{(AcO)_2Cu} = 0.972 g

Volume of the sodium chromate solution: V_{Na_2CrO_4} = 150.0 mL

Molarity of the sodium chromate solution: c_{Na_2CrO_4} = 0.0400 M

Now, when copper(II) acetate reacts with sodium chromate, an insoluble copper(II) chromate is formed:

(CH_3COO)_2Cu (aq) + Na_2CrO_4 (aq)\rightarrow 2 CH_3COONa (aq) + CuCrO_4 (s)

Find moles of each reactant. or copper(II) acetate, divide its mass by the molar mass:

n_{(AcO)_2Cu} = \frac{0.972 g}{181.63 g/mol} = 0.0053515 mol

Moles of the sodium chromate solution would be found by multiplying its volume by molarity:

n_{Na_2CrO_4} = 0.0400 M\cdot 0.1500 L = 0.00600 mol

Find the limiting reactant. Notice that stoichiometry of this reaction is 1 : 1, so we can compare moles directly. Moles of copper(II) acetate are lower than moles of sodium chromate, so copper(II) acetate is our limiting reactant.

Write the net ionic equation for this reaction:

Cu^{2+} (aq) + CrO_4^{2-} (aq)\rightarrow CuCrO_4 (s)

Notice that acetate is the ion spectator. This means it doesn't react, its moles throughout reaction stay the same. We started with:

n_{(AcO)_2Cu} = 0.0053515 mol

According to stoichiometry, 1 unit of copper(II) acetate has 2 units of acetate, so moles of acetate are equal to:

n_{AcO^-} = 2\cdot 0.0053515 mol = 0.010703 mol

The total volume of this solution doesn't change, so dividing moles of acetate by this volume will yield the molarity of acetate:

c_{AcO^-} = \frac{0.010703 mol}{0.1500 L} = 0.0714 M

8 0
3 years ago
Farmers who raise cotton once used arsenic acid, H₃AsO₄, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with
Stels [109]

Explanation:

The reaction equation will be as follows.

      H_{3}AsO_{4} \rightleftharpoons H_{2}AsO^{-}_{4} + H^{+}

Hence, the expression for K_{a} is as follows.

            K_{a} = \frac{[H_{2}SO^{-}_{4}][H^{+}]}{[H_{3}AsO_{4}]}

Let us assume that the concentration of both [H_{2}AsO^{-}_{4}] and [H^{+}] is x.

           2.5 \times 10^{-4} = \frac{x \times x}{0.5}

                          x = 0.01118034

This means that the concentration of [H^{+}] is 0.01118034.

Since, we know that the relation between pH and concentration of hydrogen ions is as follows.

              pH = -log [H^{+}]

                    = -log (0.01118034)

                    = 1.958

Thus, we can conclude that the pH of a 0.500 M solution of arsenic acid is 1.958.

6 0
3 years ago
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