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siniylev [52]
3 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]3 years ago
5 0

Answer:

the correct answer is d)

Explanation:

strojnjashka [21]3 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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A sample of the chiral molecule limonene is 62% enantiopure. what percentage of each enantiomer is present? what is the percent
ikadub [295]

The mixture contains 62 % one isomer and 38 % the enantiomer.

Let’s say that the mixture contains 62 % of the (<em>R</em>)-isomer.

Then % (<em>S</em>) = 100 % -62 % = 38 %

ee = %  (<em>R</em>) - % (<em>S</em>) = 62 % -38 % = 24 %


6 0
3 years ago
Read 2 more answers
Classify each of the following as a homogeneous or heterogeneous substance.
Mnenie [13.5K]

Answer:

a). iron ore - is a heterogeneous substance.

b). quartz - is a homogeneous substance.

c). granite - is a heterogeneous substance.

d). energy drink - is a heterogeneous substance.

e). oil-and-vinegar salad dressing - is a heterogeneous substance.

f). salt - is a homogeneous substance.

g). rainwater - is a heterogeneous substance.

h). nitrogen - is a homogeneous substance.

Explanation:

a). iron ore - is a heterogeneous substance as iron core contains iron and other impurities

b). quartz - is a homogeneous substance as it is only made up of carbon

c). granite - is a heterogeneous substance as it is made up of multiple minerals.

d). energy drink - is a heterogeneous substance as it contains various substances mixed in it

e). oil-and-vinegar salad dressing - is a heterogeneous substance as oil and vinegar itself are different compounds

f). salt - is a homogeneous substance as it only contains one type of molecule

g). rainwater - is a heterogeneous substance as it contains water and other minerals

h). nitrogen - is a homogeneous substance as it is only made of one type of molecule.

5 0
1 year ago
A sample of gas (1.9 mol) is in a flask at 21 °C and 697 mm Hg. The flask is opened and more gas is added to the flask. The new
Artyom0805 [142]

Answer: There are now 2.07 moles of gas in the flask.

Explanation:

PV=nRT

P= Pressure of the gas = 697 mmHg = 0.92 atm  (760 mmHg= 1 atm)

V= Volume of gas = volume of container = ?

n = number of moles = 1.9

T = Temperature of the gas = 21°C=(21+273)K= 294 K   (0°C = 273 K)

R= Value of gas constant = 0.0821 Latm\K mol

V=\frac{nRT}{P}=\frac{1.9\times 0.0821 \times 294}{0.92}=49.8L

When more gas is added to the flask. The new pressure is 775 mm Hg and the temperature is now 26 °C, but the volume remains same.Thus again using ideal gas equation to find number of moles.

PV=nRT

P= Pressure of the gas = 775 mmHg = 1.02 atm  (760 mmHg= 1 atm)

V= Volume of gas = volume of container = 49.8 L

n = number of moles = ?

T = Temperature of the gas = 26°C=(26+273)K= 299 K   (0°C = 273 K)

R= Value of gas constant = 0.0821 Latm\K mol

n=\frac{PV}{RT}=\frac{1.02\times 49.8}{0.0821\times 299}=2.07moles

Thus the now the container contains 2.07 moles.

6 0
3 years ago
Please help it’s due today
Romashka [77]
U literally put all yo information on their
8 0
3 years ago
What are two characteristics of a good scientific investigation
LekaFEV [45]
It's observation and a hypothesis.
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