1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
murzikaleks [220]
3 years ago
15

A fossil is any natural evidence of prehistoric life that provides some idea of the size, shape, or form of the organism. A foss

il does need not to be a whole animal or plant. Broken fragments are also fossils, as are the tracks left behind by the organisms. Fossils provide important evidence of how life and environmental conditions have changed. The fossils found in rock formations of different time periods differ because the environment on Earth has changed.
The various kinds of animals and plants that once lived in Pennsylvania provides evidence of the environmental changes of early Pennsylvania from the ___________________________.
A) very good record keeping
B) plants preserved as fossils
C) animals preserved as fossils
D) plant and animals preserved as fossils
Chemistry
2 answers:
Levart [38]3 years ago
6 0
I believe it’s C or D
yulyashka [42]3 years ago
6 0

geez the answer is D. its not C or D


You might be interested in
Nal+ pb(SO4) 2 Pbl4 + Na2SO4 explain how to balance the chemical equation and classify its reaction type
Pani-rosa [81]

Explanation:

because there are 4 Iodines on the left, we'll put. 4 in front of NaI to balance it. This would result in 4 Na on the left, so we'll put a 2 in front of Sodium Sulfate to balance the right side. Now we have 4 Na and I on both side, as well as 2 Sulfate on both sides. Pb is already balanced. The equation is now complete.

3 0
3 years ago
Helium gas diffuses 4 times as fast as an unknown gas. What is relative molecular mass of the gas​
Inessa05 [86]

The relative molecular mass of the gas​ : 64 g/mol

<h3>Further explanation</h3>

Given

Helium rate = 4x an unknown gas

Required

The relative molecular mass of the gas​

Solution

Graham's Law

\tt \dfrac{r_1}{r_2}=\sqrt{\dfrac{M_2}{M_1} }

r₁=4 x r₂

r₁ = Helium rate

r₂ = unknown gas rate

M₁= relative molecular mass of Helium = 4 g/mol

M₂ = relative molecular mass of the gas​

Input the value :

\tt \dfrac{4r_2}{r_2}=\sqrt{\dfrac{M_2}{4} }\\\\16=\dfrac{M_2}{4}\\\\M_2=64~g/mol

7 0
2 years ago
Which statement is true about intermolecular forces?
seropon [69]

Answer:

Intermolecular forces are the forces of attraction or repulsion which act between neighboring particles (atoms, molecules, or ions ). These forces are weak compared to the intramolecular forces, such as the covalent or ionic bonds between atoms in a molecule.

Importance:

Intermolecular forces are important because they determine the physical properties of substances. Many of the life-sustaining properties of water such as its high heat capacity are a result of the hydrogen bonding capabilities it has and are thus due to intermolecular forces.

4 0
3 years ago
Prove that PV = nRT.​
qaws [65]

Find your answer in the explanation below.

Explanation:

PV = nRT is called the ideal gas equation and its a combination of 3 laws; Charles' law, Boyle's law and Avogadro's law.

According to Boyle's law, at constant temperature, the volume of a gas is inversely proportional to the pressure. i.e V = 1/P

From, Charles' law, we have that volume is directly proportional to the absolute temperature of the gas at constant pressure. i.e V = T

Avogadro's law finally states that equal volume of all gases at the same temperature and pressure contain the same number of molecules. i.e V = n

Combining the 3 Laws together i.e equating volume in all 3 laws, we have

V = nT/P,

V = constant nT/P

(constant = general gas constant = R)

V = RnT/P

by bringing P to the LHS, we have,

PV = nRT.

Q.E.D

6 0
3 years ago
Explain why 2-bromopropane reacts with sodium iodide in acetone over 104 times faster than bromocyclopropane. hint: examine the
Mama L [17]

Answer:-

The reaction of 2-bromopropane reacts with sodium iodide in acetone is an example of Sn2 reaction.

The I - attacks from backside to give the transition state for both.

If we compare the transition state for cyclobromopropane 2-bromopropane then we see in case of cyclobromopropane transition state, one of the H is very close to the incoming I -.

This results in steric strain and less stability of the transition state. Hence 2-bromopropane reacts with sodium iodide in acetone over 104 times faster than bromocyclopropane.

7 0
3 years ago
Other questions:
  • Please help asap,
    7·1 answer
  • Is a push or a pull.<br><br><br> A.FORCE<br> B.MASS <br><br> ???
    9·1 answer
  • When a carbon atom joints chemically with an oxygen atom it makes carbon monoxide what is the term for carbon monoxide?
    7·1 answer
  • What type of chemical bond is hydrogen?
    6·1 answer
  • What does a Mitochondrion do
    5·2 answers
  • The elements carbon and sulfur are solids at room temperature. Can you reasonably predict that a compound of these two elements
    13·1 answer
  • Glucose, C6H12O6, is used as an energy source by the human body. The overall reaction in the body is described by the equation:
    15·1 answer
  • As a stove heats a pot, particles in the hot pot bump into particles of water 1 point
    12·1 answer
  • In the Lewis structure of BF3, how many lone pairs surround the boron atom?
    6·2 answers
  • Determina el número de moles y moléculas de 25 gr de HCI
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!