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Greeley [361]
2 years ago
13

A geologist studies layered rock to determine its age. Bacteria fossils from the Precambrian age are found in the rock’s upper l

ayers, but no fossils are found in the rock’s bottom layer. Which of these conclusions about the rock is bet supported by evidence?
Chemistry
1 answer:
kondor19780726 [428]2 years ago
4 0
Answer:
The bottom layers of the rock could have formed before life occurred.

Explanation:
The bottom layers of the rock could have formed before life occurred because there is no fossil is present. If there is life at that time so the fossils are present at the bottom layer so the absence indicates that is no life present at that time. The bottom layer is older than the upper layer so that's why fossils of bacteria are found in the upper layer of the rock.

Answer:
C. Because bacterial fossils are found only in the upper layers, scientists can conclude that these bacteria evolved towards the end of Precambrian time.

There’s two different types of answers for this question so I just put both of them. Hope it helps : )

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Which phrase is the best definition for the word common in environmental science?
andreev551 [17]
I believe that the best definition of the word common in environmental science is a typical resource. A typical resource is a resource that is not hard to find and is very common. The answer to the question will hence be A.
The answer could not be the other three choices because a shared resource is a resource that is used by more than one organism in the environment. A worthless resource is one that has no use in the environment while a rare resource is one that is hard to find.
7 0
3 years ago
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What is the speed of a softball that travels 20 m in 2 sec?
sladkih [1.3K]
The ball travels 10m/s

Speed = distance/time
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3 years ago
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Be sure to answer all parts. For the complete redox reactions given here, write the half-reactions and identify the oxidizing an
OlgaM077 [116]

Answer : O_2 is the oxidizing agent and Fe is the reducing agent.

Explanation :

Reducing agent : It is defined as the agent which helps the other substance to reduce and itself gets oxidized. Thus, it will undergo oxidation reaction.

Oxidizing agent : It is defined as the agent which helps the other substance to oxidize and itself gets reduced. Thus, it will undergo reduction reaction.

The balanced redox reaction is :

4Fe+3O_2\rightarrow 2Fe_2O_3

The half oxidation-reduction reactions are:

Oxidation reaction : Fe\rightarrow Fe^{3+}+3e^-

Reduction reaction : O_2+4e^-\rightarrow 2O^{2-}

In order to balance the electrons, we multiply the oxidation reaction by 4 and reduction reaction by 3 then added both equation, we get the balanced redox reaction.

Oxidation reaction : 4Fe\rightarrow 4Fe^{3+}+12e^-

Reduction reaction : 3O_2+12e^-\rightarrow 6O^{2-}

4Fe+3O_2\rightarrow 2Fe_2O_3

In this reaction, 'Fe' is the reducing agent that loses an electron to another chemical species in a redox chemical reaction and itself gets oxidized and 'O_2' is the oxidizing agent that gain an electron to another chemical species in a redox chemical reaction and itself gets reduced.

Thus, O_2 is the oxidizing agent and Fe is the reducing agent.

7 0
3 years ago
What is the percent composition of carbon in heptane c7h16
Gnom [1K]

Answer: the percent composition of carbon in heptane is 83.9%

Explanation:

<u>1) Atomic masses of the atoms:</u>

  • C: 12.01 g/mol
  • H: 1.008 g/mol

<u>2) Molar mass of heptane:</u>

  • C₇H₁₆: 7 × 12.01 g/mol + 16×1.008 g/mol = 100.2 g/mol

<u>3) Mass of carbon in one mole of heptane:</u>

  • C₇: 7 × 12.01 g/mol = 84.07 g/mol

<u>3) Percent composition of carbon:</u>

  • % = (mass in grams of C) / (mass in grams of C₇H₁₆) × 100 =

           = (84.07 g/ 100.2 g) × 100 = 83.9% ← answer

8 0
3 years ago
How many kilograms of solvent would contain 0.43 mol of CaO in a 2.5 molality solution
dalvyx [7]
<h3>Answer:</h3>

0.024 kg CaO

<h3>General Formulas and Concepts:</h3>

<u>Math</u>

<u>Pre-Algebra</u>

Order of Operations: BPEMDAS

  1. Brackets
  2. Parenthesis
  3. Exponents
  4. Multiplication
  5. Division
  6. Addition
  7. Subtraction
  • Left to Right

<u>Chemistry</u>

<u>Aqueous Solutions</u>

  • Molarity = moles of solute / liters of solution

<u>Atomic Structure</u>

  • Reading a Periodic Tables
  • Using Dimensional Analysis
<h3>Explanation:</h3>

<u>Step 1: Define</u>

0.41 mol CaO

2.5 M Solution

<u>Step 2: Identify Conversions</u>

1000 g = 1 kg

Molar Mass of Ca - 40.08 g/mol

Molar Mass of O - 16.00 g/mol

Molar Mass of CaO - 40.08 + 16.00 = 56.08 g/mol

<u>Step 3: Convert</u>

  1. Set up:                                \displaystyle 0.43 \ mol \ CaO(\frac{56.08 \ g \ Cao}{1 \ mol \ CaO})(\frac{1 \ kg \ CaO}{1000 \ g \ CaO})
  2. Multiply:                              \displaystyle 0.024114 \ kg \ CaO

<u>Step 4: Check</u>

<em>Follow sig fig rules and round. We are given 2 sig figs as our lowest.</em>

0.024114 kg CaO ≈ 0.024 kg CaO

4 0
3 years ago
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