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2 years ago

What prokaryotic oranism shows up as the earliest fossils?

Chemistry

2 answers:

Law Incorporation [45]2 years ago

8 0

D. Cyanobacteria hope this helps! :D

mr Goodwill [35]2 years ago

3 0

What grade are you in

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A solution is diluted by adding more _____, which means the _____ of the solution increases but the amount (moles) of solute sta

Rudik [331]

Answer:solvent ; volume

Explanation:

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2 years ago

Use bond energies to calculate the enthalpy of reaction for the combustion of ethane. Average bond energies in kJ/mol C-C 347, C

ivanzaharov [21]

The enthalpy of reaction for the combustion of ethane 2CH₃CH₃ + 7O₂ → 4CO₂ + 6H₂O calculated from the average bond energies of the compounds is -2860 kJ/mol.

The reaction is:

2CH₃CH₃ + 7O₂ → 4CO₂ + 6H₂O (1)

The enthalpy of reaction (1) is given by:

$\Delta H = \Delta H_{r} - \Delta H_{p}$ (2)

Where:

r: is for reactants

p: is for products

The bonds of the compounds of reaction (1) are:

2CH₃CH₃: 2 moles of 6 C-H bonds + 2 moles of 1 C-C bond

7O₂: 7 moles of 1 O=O bond

4CO₂: 4 moles of 2 C=O bonds

6H₂O: 6 moles of 2 H-O bonds

Hence, the enthalpy of reaction (1) is (eq 2):

$\Delta H = \Delta H_{r} - \Delta H_{p}$

$\Delta H = 2*\Delta H_{CH_{3}CH_{3}} + 7\Delta H_{O_{2}} - (4*\Delta H_{CO_{2}} + 6*\Delta H_{H_{2}O})$

$\Delta H = 2*(6*\Delta H_{C-H} + \Delta H_{C-C}) + 7\Delta H_{O=O} - (4*2*\Delta H_{C=O} + 6*2*\Delta H_{H-O})$

$\Delta H = [2*(6*413 + 347) + 7*498 - (4*2*799 + 6*2*467)] kJ/mol$

$\Delta H = -2860 kJ/mol$

Therefore, the enthalpy of reaction for the combustion of ethane is -2860 kJ/mol.

I hope it helps you!

7 0

2 years ago

Which statements indicate what the fossil record suggests about evolution on Earth? Check all that apply.

Gennadij [26K]

The following are the statements, which indicates that the fossil record suggests about evolution on Earth:

1. Humans have only recently existed on Earth.

2. The organisms originally lived only in Earth's water.

3. The plants did not have flowers when dinosaurs existed.

The fossil remains have been discovered in the rocks of all the ages. The simplest organisms fossils are witnessed in the oldest rocks, and the fossils of more composite species are found in the newest rocks. This supports the theory of evolution suggested by Darwin, according to which the simple life forms slowly gets evolved into more composite ones.

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2 years ago

Read 2 more answers

If a mixture of two metals was separated based on one metal's ability to be drawn into a thin wire, which property listed below

IrinaK [193]

Ductility because ductility is the ability to be stretched and be made into wires.

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3 years ago

The most common element in the atmosphere are

Ivanshal [37]

Nitrogen and oxygen are the most prevalent in the atmosphere.

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3 years ago