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adoni [48]
3 years ago
10

The validity of scientific theories and laws depends on evidence. Which of the following statements of evidence supports a law r

ather than a theory?
Electrons orbit the nucleus of an atom within a certain radius.
DNA analysis reveals that a modern species is related to an extinct species.
Seafloor spreading occurs at a rate of three centimeters per year in the mid-Atlantic.
The amount of matter in a closed system is the same at the start of a reaction as at the end of the reaction.

Chemistry
2 answers:
Ksju [112]3 years ago
4 0

Answer:

d the amount of matter in a closed system is the same at the start of a reaction as at the end of the reaction

mr_godi [17]3 years ago
3 0

Answer:

D

Explanation:

i am doing the test rn and i found the answer in other places

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What is the difference between liquid nitrogen and nitrogen gas​
Studentka2010 [4]

Answer:

The difference between liquid nitrogen and nitrogen gas is liquid nitrogen gas is man made or caused by humans but, nitrogen gas takes place naturally in the earths atmosphere.

Explanation:

Hope this helps :)

8 0
2 years ago
g A and B are both non-volatile molecular compounds. Substance A has a greater molar mass than substance B. If 50 g of substance
Doss [256]

Answer:

The correct answer is - option D.  the boiling point of solution A will be lower than the boiling point of solution B

Explanation:

Colligative properties such as a decrease in the freezing point of the solution, increase in the boiling point of substance, decrease in Lowering of vapor pressure, and other properties depend upon the number of molecules only.

In the given solution the equal amount of two solutions are mixed that is 50 grams however due to the difference in the molecular mass so the atoms present in both solution A and B will be different. It is known that the number of atoms of a substance is inversely proportional to the molecular mass of the particular substance.

As it is given that Solution B has a low molecular mass which means it has a high number of atoms that means its boiling point will be higher than solution A.

8 0
2 years ago
Is the measure of a quantity of energy.<br> Temperature<br> Mole<br> Heat<br> Kinetic motion
Andreas93 [3]

Answer:the answer is moles

Explanation: joules are measurements of energy, and moles Joules

4 0
3 years ago
What is the oxidizing agent in the following equation? Al (s) + 3 Ag+ (aq) produces Al^+3 (aq) + 3 Ag (s)
Keith_Richards [23]

Answer:

Ag is the oxidizing agent

Explanation:

oxidizing agent in the following equation?

Al (s) + 3 Ag+ (aq) = Al+3 (aq) + 3 Ag (s)

Left side

Al = 1

Ag = 3

Right Side

Al = 1

Ag = 3

So it's balanced already good.

Define

oxidizing agent = An oxidizing agent is the substance that gains electrons and is reduced in a chemical reaction.

Al is the reducing agent.

Ag is the oxidizing agent

7 0
3 years ago
g A solution contains 100mM NaCl, 20mM CaCl2, and 20mM urea. We would say this solution is __________ compared to a 300 mOsM sol
ICE Princess25 [194]

Answer:

A solution contains 100mM NaCl, 20mM CaCl2, and 20mM urea. We would say this solution is hypotonic compared to a 300 mOsM solution and hypotonic compared to a cell with 300 mOsM (non-penetrating solutes) interior.

Explanation:

The osmolarity is calculated from the molar concentration of the active particles in the solution. We have a solution that is composed of NaCl, CaCl₂ and urea.

When they are dissolved in water, they dissociate into particles as follows:

NaCl → Na⁺ + Cl⁻  (2 particles per compound)

CaCl₂ → Ca²⁺ + 2 Cl⁻ (3 particles per compound)

urea: not dissociation (1 particle per compound)

Then, we have to calculate the osmolarity of the solution. We multiply the molarity of each compound by the number of particles produced by the compound in water:

Osm = (100 mM NaCl x 2) + (20 mM CaCl₂ x 3) + (20 mM urea x 1) = 280 mOsm

Compared with 300 mOsm, 280 mOsm has a lower osmolarity, so it is a hypotonic solution.

To compare with a cell's osmolarity, we have to consider only the non-penetrating solutes. Urea is considered a penetrating solute for mammalian cells. So, the osmolarity of non-penetrating solutes (NaCl  and CaCl₂) is calculated as:

Osm (non-penetrating solutes) = (100 mM NaCl x 2) + (20 mM CaCl₂ x 3) = 260 mOsm

Therefore, we have:

Compared to 300 mOsm solution ⇒ 280 mOsm solution is a hypotonic solution

Compared to a cell with 300 mOsm ⇒ 260 mOsm solution is hypotonic

4 0
3 years ago
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