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1 year ago

Cells of the immune system are able to respond to the

Chemistry

1 answer:

egoroff_w [7]1 year ago

5 0

Answer:

A) antigens present on the invaders

Explanation:

Antigens are substances (usually proteins) on the surface of cells, viruses, fungi, or bacteria. Nonliving substances such as toxins, chemicals, drugs, and foreign particles (such as a splinter) can also be antigens. The immune system recognizes and destroys, or tries to destroy, substances that contain antigens

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If you examined the human body on a chemical composition basis, which of the following combinations of elements would be most co

Harlamova29_29 [7]

Answer:

Explanation:

Roughly 96% of mass of human body is made up of four elements which are oxygen, carbon, nitrogen and hydrogen.

Oxygen and hydrogen are predominantly found in the water, which makes up about 60% of body's weight. Carbon is synonymous with the life. The central role of carbon is due to fact that it has four bonding sites which allow for building of long and complex chains of the molecules. Moreover, these carbon bonds can be formed and also be broken with amount of energy which makes life alive. Nitrogen is found in organic molecules, including amino acids which make up the proteins, and nucleic acids which make up the DNA.

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3 years ago

What is one example of closed economy

Gre4nikov [31]

Some examples are like Russia, Egypt, China, Brazil

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2 years ago

Based on the current atomic theory most chemical reaction take place as a result of the interactions of which sub- atomic partic

icang [17]

Electrons, everything is pretty much based around the likeliness of electrons to be swapped or shared between atoms

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2 years ago

Which of the following statements is incorrect? A. Molecular mass is expressed in atomic mass units. B. Formula mass compares th

n200080 [17]

Answer:

The incorrect statement is the choice C. Atomic mass has units of grams per atom.

Explanation:

1) Choice A. Molecular mass is expressed in atomic mass units.

Correct. Atomic mass units (a.m.u) is the standard unit used to express the mass of the atoms and the molecules.

Since, one atom, molecule, or formula unit is a tiny amount of material, it has a ver, very low mass, and the unit mass of a molecule is referred to one mole (6.022 × 10²³ units).

2) Choice B. Formula mass compares the mass of one formula unit of a substance to the mass of one atom of carbon-12.

Correct. The masses of atoms and compounds are referred to a standard. Such standard is the carbon-12 atom. This is, the cabon-12 atom was selected as the standard and its exact mass is 12 a.m.u.

3) Choice C. Atomic mass has units of grams per atom.

Incorrect. Atomic mass is the mass of the atoms, but, since, the mass of one atom is so small, the atomic mass is referred to one mole. Hence, the atomic mass has units of grams per mole.

4) Choice D. Both molecular mass and formula mass use carbon-12 as a reference standard.

Correct. As stated when explaining the option B, the mass of atoms, molecules, and formula units are referred to carbon-12 standard.

5) Choice E. Sodium chloride, an ionic compound, is said to have a formula weight, but not a molecular weight.

Correct. The reason is that ionic compounds form large structures (crystals) and, since there is not such thing as one molecule of them, they are said to have formula weight (or mass) but not a molecular weight.

The name molecules is reserved for covalent compounds, where you can formally identify molecules. E.g. Water is a molecular compound, and each molecule has molecular formula H₂O, whose mass is the molecular mass.

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3 years ago

For each trial, compute the mol of titrant; (molarity x L) and keep the number of significant figures to 4.

MrMuchimi

Answer:

Trial Number of moles

1 0.001249mol

2 0.001232mol

3 0.001187 mol

Explanation:

To calculate the number of moles of tritant you need its molarity.

Since the molarity is not reported, I will use 0.1000M (four significant figures), which is used in other similar problems.

Molarity is the concentration of the solution in number of moles of solute per liter of solution.

In this case the solute is NaOH.

The formula is:

$Molarity=\dfrac{\text{Number of moles of solute}}{\text{Volume of solution in liters}}$

Solve for the number of moles:

$\text{Number of moles}=Molarity\times Volume\text{ }in\text{ }liters$

Then, using the molarity of 0.1000M and the volumes for each trial you can calculate the number of moles of tritant.

Trial mL liters Number of moles

1 12.49 0.01249 0.01249liters × 0.1000M = 0.001249mol

2 12.32 0.01232 0.01232liters × 0.1000M = 0.001232mol

3 11.87 0.01187 0.01187liters × 0.1000M = 0.001187 mol

3 0

2 years ago

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