chemistry question please help

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\[/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question

N = 1.505 × 10²³ Na atoms

We have

[tex]n = \frac{1.505 \times {10}^{23} }{6.02 \times {10}^{23} } = \frac{1}{4} \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

C. Physical weathering.

Answer: C. Physical weathering.

Explanation:

Answer:

The first one

Explanation:

Answer:

The six most common elements in living things are carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. Atoms of these elements combine and form thousands of large molecules. These large molecules make up the structures of cells and carry out many processes essential to life.

Explanation:

hope that helped

Different elements combine together to form an organism and other essential organic and inorganic molecules for the life and survival of organisms.

In multicellular organisms, such as animals, atoms form molecules by coming together. These atoms are present in the elements. Molecules can interact to form cells. Cells combine to form tissues, which make up organs.

At the most basic level, all organisms are made of a combination of elements:

Thus, Different elements combine together to form an organism and other essential organic and inorganic molecules for the life and survival of organisms.

Learn more about elements:

https://brainly.com/question/13025901

Answer:

B. When one element replaces another element in a compound during a chemical reaction

Answer:

Molarity = 0.425 M

Explanation:

Given data:

Number of moles = 3.7 mol

Volume of solution = 8.7 L

Molarity of solution = ?

Solution:

Molarity is used to describe the concentration of solution. It tells how many moles are dissolve in per litter of solution.

Formula:

Molarity = number of moles of solute / L of solution

Molarity = 3.7 mol/8.7 L

Molarity = 0.425 M

Answer:

Option C is correct option = 2.85×10⁻² lb/in³

Explanation:

Given data:

Density in g/mL = 0.789

Density in lb/in³ = ?

Solution:

It is given that,

2.54 cm = 1 in

2.205 lb = 1 kg   thus,

1 mL = 1 cm³

0.789 g/cm³ × 1 kg/ 1000 g × 2.205 lb/1 kg × (2.54 cm / 1in)³

2.85×10⁻² lb/in³

The density of liquid ethanol is 0.789 g/mL, which is equivalent to 0.0285 lb/in³.

A student measured the density of liquid ethanol to be 0.789 g/mL and we want to convert it to lb/in³. We will need a series of conversion factors.

A conversion factor is an arithmetical multiplier for converting a quantity expressed in one set of units into an equivalent expressed in another.

We will use the following conversion factors:

0.789 g/mL × (1 kg/1000 g) × (2.205 lb/1 kg) = 1.74 × 10⁻³ lb/mL

We will use the following conversion factors:

1.74 × 10⁻³ lb/mL × (1 mL/1 cm³) × (2.54 cm/1 in)³ = 0.0285 lb/in³

The density of liquid ethanol is 0.789 g/mL, which is equivalent to 0.0285 lb/in³.

Learn more about unit conversion here: https://brainly.com/question/13016491

Given that,

Mass number of Ge = 70

Then,

Atomic number of Ge = 32

No. of protons = 32

No. of electrons = 32

No. of neutrons,

→ 70 - 32 = 30

Answer:

30 is correct

Explanation:

70 - 32 = 30 mark as brainliest

Answer:

1551.45 MmHg

hope this helps :D

Answer:

3564 = 3.564 x 10^3

Explanation:

i.e expresing the value in standard form.

Answer:

0.2756 L

Explanation:

0.2756 L

Answer:

radioisotope dating is another name

Answer:

Radiometric dating

Explanation:

hope that helps

Answer:

D)Polishing..

Answer:

Wouldn't it be rusting

Explanation:

Melting and bending are physical changes so is polishing. so rusting is the only choice, for metal to rust wouldn't it need a chemical change.

Answer:

C. Anything That Takes Up Space.

Explanation:

Answer:The answer is B my child

Explanation:

Answer:

I'm pretty sure it's electrons

Answer:

3 element i.e carbon (C), hydrogen (H) and oxygen.

Explanation:

The following data were obtained from the question:

Subtance >>>>>>>> Chemical Formula

Glucose >>>>>>>>> C₆H₁₂O₆

Methane >>>>>>>> CH₄

Ethanol >>>>>>>>> C₂H₅OH

Hydrogen peroxide >> H₂O₂

From the above table, we can see that ethanol (C₂H₅OH) contains carbon (C), hydrogen (H) and oxygen

Therefore, the total number of elements present in ethanol, C₂H₅OH is 3.

Answer:

I think all of the above

Explanation:

Put as brainliest if you wish

Answer:

2.878 (w/w)%

Explanation:

The reaction of NH3 with HCl is:

NH3 + HCl → NH4Cl

That means 1 mole of ammonia reacts per mole of HCl. The moles of HCl that reacts = Moles of ammonia are:

14.22mL = 0.01422L * (0.1063mol HCl / L) = 0.001512 moles HCl = Moles ammonia

In mass:

0.001512 moles NH3 * (17.031g / mol) = 0.02574g of NH3 in the solution.

The concentration in weight percent of the diluted solution is:

0.02574g of NH3 / 4.373g * 100 = 0.5887 (w/w)%

This is the concentration of the diluted solution that was diluted from 10.151g to 10.151g + 39.466g = 49.617g

-Assuming density of water = 1g/mL-

The solution was diluted:

49.617g / 10.151g = 4.888 times.

That means the concentration of NH3 in the original cleaner is:

0.5887 (w/w)% * 4.888 =

Answer:

Both b and c i think so... .

I think it is the dark blue tile because if it is not soluble, or insoluble, then it will not dissolve and you will still see it floating around in the liquid or at the bottom of the container.

Answer:

d. 93 degree Celsius

Explanation:

Plzzzzzzzzzzzzzzzzzzzzzzz mark AS BRAINLIST

Answer:

hope it helps..

Explanation:

'Motile' (or moving) cilia are found in the lungs, respiratory tract and middle ear. ... These cilia have a rhythmic waving or beating motion. They work, for instance, to keep the airways clear of mucus and dirt, allowing us to breathe easily and without irritation.

Answer: to keep airway clear of mucus and dirt allowing us to breathe easy

Explanation:

Answer:

1) Eₐ = 100.3 kJ/mol

2) k = 7.62×10⁻⁴ M⁻¹s⁻¹

Explanation:

1) Make an Arrhenius graph by plotting ln(k) on the y-axis and 1/T on the x-axis (don't forget to convert temperature to Kelvin).

The slope of the line is equal to -Eₐ/R.

-Eₐ/R = -12065

Eₐ = 100,300 J/mol

Eₐ = 100.3 kJ/mol

2) Since we know the slope of ln(k) vs 1/T is -Eₐ/R, we can say:

-Eₐ/R = (ln(k₂) − ln(k₁)) / (1/T₂ − 1/T₁)

Plug in values and solve for k:

-(108,000 J/mol) / (8.314 J/mol/K) = [ln(k) − ln(1.0×10⁻³)] / [1/(35+273.15 K) − 1/(37+273.15 K)]

-12990 = [ln(k) + 6.91] / (2.09×10⁻⁵ K⁻¹)

-0.272 = ln(k) + 6.91

ln(k) = -7.18

k = 7.62×10⁻⁴ M⁻¹s⁻¹

Answer:

Mass of iron oxide: 79.85 g  

Explanation:

Given data:

Mass of iron = 112 g

Mass of O₂ = 24 g

Mass of iron oxide formed = ?

Solution:

4Fe + 3O₂         →       2Fe₂O₃

Number of moles of Fe:

Number of moles = mass/ molar mass

Number of moles = 112 g/ 55.85 g/mol

Number of moles =  2 mol

Number of moles of O₂:

Number of moles = mass/ molar mass

Number of moles = 24 g/ 32 g/mol

Number of moles =  0.75 mol

Now we will compare the moles of oxygen and iron with iron oxide.

                 Fe           :             Fe₂O₃

                 4             :                2

                 2             :                2/4×2 =  1

                O₂            :             Fe₂O₃

                 3             :                2

                 0.75       :                2/3×0.75 =  0.5

The number of moles of iron oxide formed by oxygen are less thus it will be limiting reactant.

Mass of iron oxide:

Mass = number of moles × molar mass

Mass = 0.5 mol  × 159.69 g/mol

Mass = 79.85 g  

Answer:

136 g Fe2O3

Explanation:

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Answer:

Explanation:

[tex]\frac{r_1}{r_2} = \sqrt{\frac{M_2}{M_1} }[/tex]

r₁ and r₂ are rate of diffusion of gas having molecular mass of M₁ and M₂

[tex]\frac{31.5}{30.5} = \sqrt{\frac{32}{M_1} }[/tex]

1.0666 = 32 / M₁

M₁ = 30

molecular weight of NO = 14 + 16 = 30

So the unknown gas is NO .