Compounds have different properties than the elements they are made from because
A . They are produced from a chemical change . B. They are produced by a physical change. C. A new substance is not made . D. Smoke , change or color, production of gas does not occur during the process.

Answer:

3.7

Explanation:

Significant figures:

All non-zero digits are consider significant figures like 1, 2, 3, 4, 5, 6, 7, 8, 9.

Leading zeros are not consider as a significant figures. e.g. 0.007 in this number only one significant figure present which is 7.

Zero between non zero digits are consider significant such as  1004 consist of four significant figures.

The zeros at the right side such as 4500 are also significant. There are four significant figures are present.

When we add or subtract the values the number of significant figures after decimal in result must be equal to the given measurement having less number of decimal places.

When we multiply or divide the values the number of significant figures must be equal to the less number of significant figures in given value.

Now we will calculate the difference between 7.69 and 4.0.

7.69 - 4.0 = 3.69

In given values 4.0 have less number of decimal places thus result must have only one decimal places. So we would round the result.

3.7

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:

Explanation:

Physical change is easily reversible. Burning/combustion is a chemical process where substances react rapidly with oxygen: this is usually irreversible.

The marshmallow, roasted food and burned wood all undergo combustion and hence are tagged chemical changes.

I hope this helps.

Answer:

Chopping Wood

Heating Water

Explanation:

Answer:

for more details are in the pic

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:

It would be 3.1063937724731447 moles.

Hope this helps :)

Answer:

The correct option is;

(B) [tex]\Delta H_{mix} < 0[/tex], solution shows negative deviation

Explanation:

The given parameters are;

The available volume of liquid A = 25 cm³

The available volume of liquid B = 20 cm³

The volume of the solution (mixture) = 44.8 cm³

Therefore, we have;

[tex]\Delta _{mix} V < 0[/tex]

Which is one of the prerequisite for the formation of negative deviation

When a non-ideal solution shows negative deviation according to Raoult's Law, we have;

[tex]\Delta _{mix} H < 0[/tex], we have more heat released due to new molecular interactions.

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:

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:

See explanation

Explanation:

This question is obviously supposed to be a multiple choice question but the options are missing.

However, the question intends to test the student's knowledge about combustion of fossil fuels. Fossil fuels are mostly composed of hydrocarbons of different chain lengths.

The longer the chain length, the greater the energy released when the compound is burnt since there are more energy stored in its bonds.

Hence, the correct answer to this question will be the option that contains the greatest number of C-C and C-H bonds.

When you increase the pressure, the molecules have less space in which they can move. That greater density of molecules increases the number of collisions. When you decrease the pressure, molecules don't hit each other as often and the rate of reaction decreases. Pressure is also related to concentration and volume.

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Answer:

Breast Cancer occurs in a lot of women.

Explanation:

The following are some symptoms of breast cancer in women.

New lump in the breast or underarm (armpit).

Thickening or swelling of part of the breast.

Irritation or dimpling of breast skin.

Redness or flaky skin in the nipple area or the breast.

Pulling in of the nipple or pain in the nipple area.

Nipple discharge other than breast milk, including blood.

Another thing is that women each year after age 40 are encouraged to get a mamogram.

Answer:

yes breast cancer can occur in both men and women.

Explanation:

some warning signs can be feeling a new lump on or around the breast or in the arm pit area, swollen or redness, also discharge from the nipple can be a sign of breast cancer. Breast pain that doesn't go away can be a sign of breast cancer.

hope this helps some. have a great night!

Answer:

Ke = mgv

Explanation:

(60)(9.81)(2) =1177.2 joules persecond or Watts.

1.177 kilowatts

                                Its true im pretty sure

It's true

Hope this helped!

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.

Answer:

Na(0.93) & F(3.98)

K(0.82) & Cl(3.16)

Cs(0.79) & Br(2.96)

Explanation:

Answer: is C

Explanation:

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:

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:

The mass of 10 moles of helium is: 2.5

Answer:

the trigger . it's the trigger

Answer:

It is the handle

Explanation:

I know because I did this test in school

Answer:

What are the Answer choices

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:

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:

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:

Oxgen- cannot be separated

Water - chemical change

Gold - cannot be separated

Carbon Dioxide - chemical change

Carbon​ - cannot be separated

Explanation:

A pure substance, which can either be an element or a compound, contains only one type of such element or compound. In opposition to a mixture, pure substances cannot be separated by physical means.

- Elements as a pure substance cannot be separated because it contains only one type of atom. However, compounds contain two or more types of atoms, and hence, can only be separated into its individual atoms via chemical means.

In this question, oxygen (O2), Gold (Au) and carbon (C) are all elements and hence cannot be separated. Carbon dioxide (CO2) and water (H2O) are compounds because they contain two different atoms respectively, hence, can be separated into individual atoms.

Answer:

H₂

Explanation: