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siniylev [52]
4 years ago
15

The fossil record is the record of life on earth preserved in rock as fossils. The fossil record provides evidence of what types

of plant and animals lived, how long they lived, how they died, and changed. It also tells us about Earth’s early environment, and how it changed. The fossil record helps determine the age of rock formations by looking at how deep the fossil are buried in the rock. When a fossil is found above another fossil in a rock formation, the deeper fossil are considered older.
What can scientists infer about a specific period of Earth's history if many fossils were discovered from oxygen-breathing organisms?
A) the atmosphere lacked oxygen
B) only fish lived during that time
C) the dinosaurs used all the oxygen
D) the atmosphere had lots of oxygen
Chemistry
2 answers:
Yuki888 [10]4 years ago
5 0

Answer:

the correct answer is d)

Explanation:

strojnjashka [21]4 years ago
3 0

Answer:

d is wrong the correct answer is b

Explanation:

The atmosphere lacked oxygen is correct. The lack of animals that used oxygen suggests that the environment did not have much oxygen.

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To what family of the periodic table does this new element probably belong
julsineya [31]
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6 0
3 years ago
Which subatomic particle adds atomic mass to an atom but without adding charge? A. ion B. proton C. electron D. neutron
alexandr1967 [171]
Neutron is the answer, it has no charge
4 0
4 years ago
Read 2 more answers
2A(g) + B(l) ⇌ 3C(aq) + D(s)
makvit [3.9K]

Answer:

B

[(0.75)^3(0.25)]÷[(0.50)^2(0.75)]

Explanation:

toppr dot com

8 0
3 years ago
A student mixes in a test tube 3.00mL of 0.050M CuSO4with 7.00mL of 0.20M NH3/NH41 . The solution becomes a deep blue color. Ass
valkas [14]

Answer:

\large \boxed{\text{0.0035 mol/L}}

Explanation:

We are given the volumes and concentrations of two reactants, so this is a limiting reactant problem.

We know that we will need moles, so, lets assemble all the data in one place.

                   Cu²⁺ + 4NH₃ ⟶ Cu(NH₃)₄²⁺

    V/mL:   3.00      7.00

c/mol·L⁻¹:  0.050   0.20

1. Identify the limiting reactant

(a) Calculate the moles of each reactant  

\text{Moles of Cu}^{2+}= \text{3.00 mL solution} \times \dfrac{\text{0.050 mmol Cu}^{2+}}{\text{1 mL solution}} = \text{0.150 mmol Cu}^{2+}\\\\\text{Moles of NH}_{3} = \text{7.00 mL solution} \times \dfrac{\text{0.20 mmol NH}_{3}}{\text{1 mL solution}} = \text{0.140 mmol NH}_{3}

(b) Calculate the moles of Cu(NH₃)₄²⁺ that can be formed from each reactant

(i) From Cu²⁺

\text{Moles of Cu(NH$_{3}$)$_{4}$$^{2+}$} = \text{0.150 mmol Cu}^{2+} \times \dfrac{\text{1 mmol Cu(NH$_{3}$)$_{4}$$^{2+}$}}{\text{1 mmol Cu}^{2+}}\\\\= \text{0.150 mmol Cu(NH$_{3}$)$_{4}$$^{2+}$}

(ii) From NH₃

\text{Moles of Cu(NH$_{3}$)$_{4}$$^{2+}$} = \text{0.140 mmol NH}_{3} \times \dfrac{\text{1 mmol Cu(NH$_{3}$)$_{4}$$^{2+}$}}{\text{4 mmol NH}_{3}}\\\\= \text{0.0350 mmol Cu(NH$_{3}$)$_{4}$$^{2+}$}

NH₃ is the limiting reactant, because it forms fewer moles of the complex ion.

(c) Concentration of the complex ion

\text{The reaction forms 0.0350 mmol Cu(NH$_{3}$)$_{4}$$^{2+}$ in a total volume of 10.00 mL.}\\c = \dfrac{\text{moles}}{\text{litres}} = \dfrac{\text{0.0350 mmol}}{\text{10.00 mL}} = \textbf{0.0035 mol/L}\\\\\text{The concentration of the complex ion is $\large \boxed{\textbf{0.0035 mol/L}}$}

7 0
3 years ago
Does cm² mean with the power of two?
sweet [91]

yup it's correct because we multiply cm by cm twice

4 0
3 years ago
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