which observation provided Albert Einstein the clue that he needed to explain the photoelectric effect?
​

Answer:

D

Explanation:

Answer:

Explanation:

The density of a substance can be found by using the formula

[tex]density = \frac{mass}{volume} \\ [/tex]

From the question we have

[tex]density = \frac{1.2}{2.4} \\ [/tex]

We have the final answer as

Hope this helps you

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 we have

[tex]n = \frac{2.39 \times {10}^{23} }{6.02 \times {10}^{23} } \\ = 0.39700996...[/tex]

We have the final answer as

Hope this helps you

Answer:

Butane has only two isomers and pentane has just three, but some hydrocarbons have many more isomers than these. As you increase the number of carbon atoms in a hydrocarbon, the number of isomers quickly increases.

Answer:

Phlogopite

Explanation:

It is a member of mica group family of phyllosilicates mineral. It is the magnesium endmember of the biotite stable - the chemical formulation KMg3AlSi3O10 (F, OH) 2.

Answer:

100g / (5.2g/cm3)

= 100g / (5.2g / 1cm3)

= 100g x 1cm3 / 5.2 g

= 19.2 cm3

Since 1 cm3 = 1 ml, your answer is 19.2 ml.

The given density and mass of the metallic piece can be used to estimate the volume of the substance. The metal with a mass of 100 gm and a density of 5.2 g/cm³ has a volume of 19.23 ml.

The density of the substance has been given by the ratio of mass to the volume of the substance in g/cm³ or g/mL. It shows the packaging of the molecules in the substances and has been in inverse relation to the volume.

The mass being constant and an increase in volume decreases the density of the substance and vice versa. The volume can be calculated as:

Volume = mass ÷ density

Given,

Density of the metal (ρ) = 5.2g/cm³

Mass of the metal piece (m) = 100g

Volume = V

Substituting the values above as:

ρ = m ÷ V

V = m ÷ ρ

V = 100 ÷ 5.2

= 19.23 mL

Therefore, 19.23 mL is the volume of water that spilled out of the jar.

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Answer:

It would be 3.1063937724731447 moles.

Hope this helps :)

Carbon tetrachloride, also known by many other names (such as tetrachloromethane, also recognised by the IUPAC, carbon tet in the cleaning industry, Halon-104 in firefighting, and Refrigerant-10 in HVACR) is an organic compound with the chemical formula CCl4.

Phosphorus pentoxide is a white solid that has no noticeable smell. This substance has the chemical formula P₄O₁₀. But its name comes from its empirical formula, P₂O₅. Here the correct option is B.

This substance is a white solid with a crystalline structure at room temperature. An acid anhydride made from phosphoric acid is phosphorus pentoxide. Due to its strong hygroscopicity, it is employed as a desiccant and a dehydrating agent.

When in contact with water, phosphorus pentoxide hydrolyzes quickly and violently. This reaction produces a lot of heat. The four polymorphs of this chemical that crystallize are different. Because it is so corrosive, metals must be kept away from it.

Thus the correct option is B.

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Answer:

After 7.648 days, you will see one quarter.

Explanation:

1 → 0.5 → 0.25

Since half life of radon-222 is 3.824 days, you need twice this time to get one quarter at the end.

2 ⋅ 3.824 = 7.648 days.

Answer:

A

Explanation:

Animals take in oxygen and convert it into carbon dioxide therefore the oxygen levels will decrease and the carbon dioxide levels will increase

If an animal is placed into a sealed container for a short time, the oxygen level will:  decrease and the carbon dioxide level will increase.

The oxygen held inside the space is quickly being consumed by the freight or because of rusting inside a space, and that encased spaces must consistently be treated as perilous. And the carbon dioxide levels on the other hand will increase.

It will not take a long time for an animal to survive under these conditions.

Thus. option A is correct.

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Answer:

11

Explanation:

16 orange blocks = 4*5stickers

20 stickers=20*2/7 toy soldiers =40/7 toy soldiers

40/7 toy soldiers=40/7*6/3 dinosaurs =40*2/7=80/7 =11.43 ~~ 11 dinosaurs

Answer:

a) 7.14e19 Hz

b) 2.298e-27 J

c) 2.793e-19 J; 7.117e9 nm

d) 7.5e14 Hz; 4.96e-19 J

e) 6.2947e-18 J; 31.6 nm

f) 2.21e-22 J

g) 7.1e-19 J; 1.1e15 Hz

h) 3.422e-19 J; 581 nm

i) 4.2e14 Hz

j) 1.92e8 m

k) 7.14e16 Hz; Ultraviolet

Explanation:

Frequency: ν       Wavelength: λ       Energy: E       Speed of light: C (3.00e8)       Planck's Constant: h (6.626e-34)

ν -> λ    λ = C/ν

λ -> ν    ν = C/λ

For either of these equations, wavelength must be converted to meters or nanometers, depending on the equation.

For ν -> λ, after doing the equation, convert the wavelength into nanometers by dividing by 1e-9.

For converting λ -> ν, convert the wavelength into meters by multiplying by 1e-9.

For energy: E = hν = hc/λ

Now that the setup is out of the way:

a) Violet light has a wavelength of 4.20 x 10-12 m. What is the frequency?

λ -> ν    ν = C/λ

[tex]\frac{3.00e8}{4.20e-12}[/tex] = 7.14e19 Hz

b) A photon has a frequency (n) of 3.468 x 106 Hz. Calculate its energy

E = hν = hc/λ

(6.626e-34) (3.468e6) = 2.298e-27 J

c) Calculate the energy (E) and wavelength (l) of a photon of light with a frequency of 4.215 x 1014 Hz.

E = hν = hc/λ

(6.626e-34) (4.215e14) = 2.793e-19 J

ν -> λ    λ = C/ν

[tex]\frac{3.00e8}{4.215e14}[/tex] = 7.117 m

[tex]\frac{7.117m}{1}*\frac{1nm}{1e-9m}[/tex] = 7.117e9 nm

d) Calculate the frequency and the energy of blue light that has a wavelength of 400 nm  (h = 6.62 x 10-34 J-s).

λ -> ν    ν = C/λ

[tex]\frac{400 nm}{1} *\frac{1e-9m}{1nm}[/tex] = 4e-7 m

[tex]\frac{3.00e8}{4e-7}[/tex] = 7.5e14 Hz

E = hν = hc/λ

(6.626e-34) (7.5e14) = 4.96e-19 J

e) Calculate the wavelength and energy of light that has a frequency of 9.5 x 1015 Hz.

ν -> λ    λ = C/ν

[tex]\frac{3.00e8}{9.5e15}[/tex] = 3.16e-8 m

[tex]\frac{3.16e-8m}{1}*\frac{1nm}{1e-9m}[/tex] = 31.6 nm

E = hν = hc/λ

(6.626e-34) (9.5e15) = 6.2947e-18 J

f) A photon of light has a wavelength of 0.090 cm. Calculate its energy.

E = hν = hc/λ

Convert the wavelength from cm to meters:

[tex]\frac{0.090cm}{1} *\frac{1m}{100cm}[/tex] = 9e-4 m

[tex]\frac{(6.626e-34)(3.00e8)}{9e-4}[/tex] = 2.21e-22 J

g) Calculate the energy and frequency of red light having a wavelength of 2.80 x 10-5 cm.

E = hν = hc/λ

Convert the wavelength from cm to meters:

[tex]\frac{2.80e-5cm}{1} *\frac{1m}{100cm}[/tex] = 2.8e-7 m

[tex]\frac{(6.626e-34)(3.00e8)}{2.8e-7}[/tex] = 7.1e-19 J

λ -> ν    ν = C/λ

Convert the wavelength from cm to meters:

[tex]\frac{2.80e-5cm}{1} *\frac{1m}{100cm}[/tex] = 2.8e-7 m

[tex]\frac{3.00e8}{2.8e-7}[/tex] = 1.1e15 Hz

h) Calculate the energy (E) and wavelength (l) of a photon of light with a frequency of 5.165 x 1014 Hz.

E = hν = hc/λ

(6.626e-34) (5.165e14) = 3.422e-19 J

ν -> λ    λ = C/ν

[tex]\frac{3.00e8}{5.165e14}[/tex] = 5.81e-7 m

[tex]\frac{5.81e-7m}{1}*\frac{1nm}{1e-9m}[/tex] = 581 nm

i) The wavelength of green light from a traffic signal is centered at 7.20 x 10-5 cm. Calculate the frequency.

λ -> ν    ν = C/λ

Convert the wavelength from cm to meters:

[tex]\frac{7.20e-5 cm}{1} *\frac{1m}{100cm}[/tex] = 7.2e-7 m

[tex]\frac{3.00e8}{7.2e-7}[/tex] = 4.2e14 Hz

j) If it takes 1.56 seconds for radio waves (which travel at the speed of light) to reach the moon from Earth, how far away is the moon?

  All we want to do here is to convert frequency (speed) to wavelength (distance). This problem requires a bit of thought, but it isn't bad once you realize that frquency is speed and wavelength is distance. It becomes just like the other problems after that. Also, I'll leave this distance in meters, but I think you can figure out how to convert it if it wants it in another unit.

  One second is equal to 1 Hertz, so our frequency is 1.56 Hz.

ν -> λ    λ = C/ν

[tex]\frac{3.00e8}{1.56}[/tex] = 1.92e8 m

  The actual distance from the earth to the moon via google is 3.84e7, but sometimes problems like this will mess with the numbers to make sure that you didn't just look up the answer. I'm still pretty sure that this is right, however.

k) Calculate the frequency of light that has a wavelength of 4.20 x 10-9m. Identify the type of electromagnetic radiation.

First, we convert wavelength to frequency, as normal:

λ -> ν    ν = C/λ

[tex]\frac{3.00e8}{4.20e-9}[/tex] = 7.14e16 Hz

Then we identify the electromagnetic wave type. You can look up a conversion chart for these on google, but since our frequency is in the e15 - e17 range, this light is considered ultraviolet.

The answer fam is......... False

Answer:

The mass of 10 moles of helium is: 2.5

Answer:

Al2 O3 or 2:3

Explanation:

The aluminum oxide consists of two elements, which are oxygen atoms and aluminum atoms, and there are 2 aluminum atoms and 3 oxygen atoms in aluminum oxide. The ratio from aluminum atoms to oxygen atoms is 2:3.

There are two types of chemical compound one is covalent compound and other is ionic compound, covalent compound formed by sharing of electron and ionic compound formed by complete transfer of electron. Therefore, the ratio of aluminum atoms to oxygen atoms in aluminum oxide is  2:3.

Chemical Compound is a combination of molecule, Molecule forms by combination of element and element forms by combination of atoms in fixed proportion.

An ionic compound is a metal and nonmetal combined compound.  Ionic compound are very hard. They have high melting and boiling point because of strong ion bond. The ratio of aluminum atoms to oxygen atoms in aluminum oxide is  2:3. Aluminium oxide is an ionic compound.

Therefore, the ratio of aluminum atoms to oxygen atoms in aluminum oxide is  2:3.

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Answer:

False

Explanation:

A mixture is composed of two or more substances that are combined through physical means. It has NOT undergo any changes in its chemical properties. So, even though its appearance change, it can be reverted back.

Answer:

That answer would be false.

Explanation:

Depending on the type of mixture, you can separate it and reverse it back to its original properties through filtration, evaporation, distillation, and chromatography.

Answer:They indicate the number of molecules of each substance

Explanation:

When we write chemical reaction equations, we usually put a number before the symbol of each reactant.

These coefficient shows the number of molecules of that specie that is involved in the balanced reaction equation for the reaction.

These coefficients are important because they are used in carrying out stoichiometric calculations.

Answer:

a

Explanation:

Answer:

All of the above

Explanation:

I know about the first two choices but not so much about the last one

Answer:

0.013g/cm^3

Explanation:

density= mass÷volume

Answer:

0.01(3) g/cm3 (cm3 means centimeter cubed, (3) means the 3 goes on forever)

Explanation:

The volume of the sheet is 300 cm3, and dividing 4 grams by 300 cm3 gets you 0.01(3) g/cm3. Hope it helps!

Answer:

to be honest I don't know

Explanation:

my brain won't work with this

Answer:

=0.00123

Explanation:

Look at the attachments below

Hope this helps (:

Answer:

0.00123

Explanation:

Standard notation is the normal way of writing numbers. Examples include 1, 2, and 10. The number 1.23 x 10^-3 is written in scientific notation. The decimal goes after the first nonzero integer and it is multiplied by a power of 10. The power or exponent attached to the 10 tells you how many places over you need to move the decimal to get back into scientific notation. Examples include 1.00 x 10^2 (representing 100 in standard form because you would move the decimal two places to the right.), 2.0 x 10^1 (representing 20 in standard form because you would move the decimal one place to the right), and 3.0 x 10^-4 (representing 0.0003 in standard form because you would move the decimal four places to the left since it is a negative exponent).

The negative (-3) exponent in 1.23 x 10^-3 indicated to move the decimal three places to the left. If it was positive, you would move it three places to the right.

In 1.23 x 10^-3 move the decimal to the left 1 place to get:

0.123

two places to get:

0.0123

and a third place to get:

0.00123

The final answer is 0.00123

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 we have

[tex]n = \frac{4.5 \times {10}^{24} }{6.02 \times {10}^{23} } \\ = 7.47508...[/tex]

We have the final answer as

Hope this helps you

Answer: is C

Explanation: