Can you help me please

Answer:

Detail is given below.

Explanation:

1) Chemical change cannot be undone or reversed.

The given statement is correct. Because,

Chemical change:

The changes, that occur due to change in the composition of a substance and result in a different compound is known as chemical change.

These changes are irreversible .

Example:

Combustion of fuel or wood: that oil or wood convert into energy, CO2 and ash in case of wood  and this reaction can not be reversed.

2) Physical change often cannot be undone or reversed.

The given statement is incorrect.

Physical Change                                                                                              

The changes that occur only due to change in shape or physical properties but their chemical or internal composition remain unchanged.  

These changes were reversible.

Example :

Water converting to Ice

Water converting to gas

3) In chemical change, you end up with the same substance you started with

The given statement is incorrect. Consider the following example.

The reaction of Hydrogen and oxygen:

H₂ (g)  + O₂  (g) -------------------------------------> 2H₂O  (l)

A totally new compound is formed when oxygen and hydrogen are undergo reaction which is water.

4) In physical change, particles of 2 or more substances rearrange to form new or different substance.

The given statement is incorrect.

When particles rearrange them selves the different substance is not formed. Consider the example of water when it converted into ice or vapors. Only phase is changed but water retain its properties so new substance is not formed.

Answer:

9.702450607255294

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Answer:

This story that is related to the movement of water in relation to the amount of solute seeks to explain the process of OSMOSIS in a very interesting way.

Explanation:

The OSMOSIS process is a process where water diffuses from a compartment with fewer solutes to one with higher solutes, that is why the osmotic intention is to balance the concentrations and molarities between both compartments, this is called osmotic balance.

For this to happen, a highly water-permeable barrier is needed.

Answer:

A chemical change happens when one chemical substance is transformed into one or more different substances,

Explanation:

Answer:

D

Explanation:

Meiosis is a series of steps that divides the cell's DNA  best explains the process of meiosis. Therefore, option D is correct.

A type of cell division in which each daughter cell receives half the DNA of the parent cell. In mammals, meiosis occurs during the formation of egg and sperm cells.

Due to the fact that cell division occurs twice during meiosis, a single starting cell can produce four gametes (eggs or sperm). Cells go through four stages during each round of division: prophase, metaphase, anaphase, and telophase.

Meiosis is also important for allowing genetic diversity and facilitating the repair of genetic defects via recombination.

Daughter cells are diploid after meiosis and have twice as much genetic material, which can be divided in an infinite number of ways.

Thus, option D is correct.

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Answer:

Sugar will dissolve, so water.

Explanation:

Sugar is a bicubacle food source you could say, sand will not evaporate or dissolve in the water since it is not a 3c2e source. Using water will seperate them.

Answer: Heat

Explanation:

Because is you put water and sand in a container you can separated by boiling the water and all the water would evaporate and the sand would stay.

Explanation:

Each orbital within a particular sublevel is distinguished by its value of ml. This quantum number may be more aptly named the orbital orientation quantum number. In each energy sublevel (designated by l) there are 2l+1 possible independent orientations of the electron cloud.

Answer:

[tex]m_l-magnetic[/tex]

Explanation:

The principal energy level, n, tells us which shell it is in and the total energy of the electron.

The angular momentum (azimuthal), l, tells us which sublevel/subshells the electron is in.

The magnetic, m sub l, tells us the orientation the electron is spinning.

Answer:

Chlorofluorocarbons and hydrochlorofluorocarbons are fully or partly halogenated paraffin hydrocarbons that contain only carbon, hydrogen, chlorine, and fluorine, produced as volatile derivative of methane, ethane, and propane. They are also commonly known by the DuPont brand name Freon.

Explanation:

Answer:

Explanation: Chlorofluorocarbons and hydrochlorofluorocarbons are fully or partly halogenated paraffin hydrocarbons that contain only carbon, hydrogen, chlorine, and fluorine, produced as volatile derivative of methane, ethane, and propane. They are also commonly known by the DuPont brand name Freon

Answer:

Explanation:

The volume of the marble can be found by using the formula

volume = final volume of water - initial volume of water

So we have

volume of marble = 61 - 45

We have the final answer as

Hope this helps you

Answer:

16mL

Explanation

Answer: In the early 20th century, Wegener published a paper explaining his theory that the continental landmasses were “drifting” across the Earth, sometimes plowing through oceans and into each other.

Explanation:  He called this movement continental drift.

Answer: Isotopes

Explanation:

The atoms of a chemical element can exist in different types. These are called isotopes. They have the same number of protons (and electrons), but different numbers of neutrons. Different isotopes of the same element have different masses.

Hope this helps!

Answer:

D. Chemical and physical properties

Answer:

Adding soap would cause the paper clip to fall through the water and onto the base of the dish because soap is a surfactant.

Explanation:

The concept surface tension is used here to determine what happens to the paperclip when a drop of dish soap is added to the water. Here the paperclip sink into the water.

The property exhibited by the surface of a liquid in order to resist the action of an external force because of the cohesive nature of the molecules is known as the surface tension. Due to this property the surface of a liquid behaves as an extended elastic membrane.

The paperclip float on water because of the high surface tension as the water molecules at the surface are strongly attracted among themselves. But on adding one or two drops of dish soap to water causes the paperclip to sink.

The addition of the drops of dish soap to the water weakens the attraction among the water molecules and thereby lowers the surface tension. As a result of this the surface film disappears and the paperclip sink into the water.

Thus the paperclip fall into the water when a drop of dish soap is added to the water.

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Answer:

t = 27 s

Explanation:

Given data:

Average acceleration = -0.50 m/s²

Time taken to reach to the 13.5 m/s = ?

Solution:

Formula:

Vf = V₀ + at

Vf = 0

V₀ = 13.5 m/s

a = -0.50 m/s²

Now we will put the values in formula.

0 = 13.5 m/s - 0.50 m/s²t

0.50 m/s²t =  13.5 m/s

t =  13.5 m/s / 0.50 m/s²

t = 27 s

Answer:

4.00 g/mL

Explanation:

Density is mass divided by volume (g/mL).

Mass of rock = 21.58

Volume of rock = 25.4 - 20.0 = 5.4mL

Density of rock = 21.58g / 5.4mL = 3.99629 g/mL

Round to the lowest number of significant figures which is three = 4.00 g/mL

Answer:

Explanation:

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

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

From the question

mass = 768 g

volume = 24 cm³

We have

[tex]density = \frac{768}{24} \\ [/tex]

We have the final answer as

Hope this helps you

Answer:

The density of wood is 32 g/cm³.

Explanation:

Given data:

Mass of wood = 768 g

Volume of wood = 24 cm³

Density of wood = ?

Solution:

Density is equal to the mass divided by its volume.

Formula:

d = m/v

d = density

m = mass

v = volume

d = 768 g/ 24 cm³

d = 32 g/cm³

The density of wood is  32 g/cm³.

I tihink it will help you

Answer:

b

Explanation:

becuase of sound waves

Answer:

44894

Explanation:

The specific heat  capacity of the metal : 0.610 J/g° C  

The law of conservation of energy can be applied to heat changes, i.e. the heat received/absorbed is the same as the heat released  

Q abs = Q received  

Heat can be calculated using the formula:  

Q = mc∆T  

Q = heat, J  

m = mass, g  

c = specific heat, joules / g ° C  

∆T = temperature difference, ° C / K  

∆T = T(final temp) - T(initial temp)

mass of metal = 38 g

T initial metal = 92 °C

mass of water = 43 g

T final water = 30  °C

T initial water = 22°C

c water = 4.18 J/g° C  

[tex]\tt Q=m.c.\Delta T\\\\Q=43\times 4.18\times (30-22^oC)\\\\Q=1437.92~J[/tex]

Q water = Q metal

[tex]\tt 1437.92=38\times c\times (92-30)\\\\c=0.610~J/g^oC[/tex]

Answer:

3.16×10⁹ pL

Explanation:

Given data:

Volume in mL = 3.16

Volume in picoliters = ?

Solution:

Picoliter and milliliters are units of volume. Milliliter is greater unit than picoliter.

1 mL = 10⁹ pL

Now we will convert the 3.16 mL into pL.

3.16 mL × 10⁹ pL/ 1 mL

3.16×10⁹ pL

Answer:

3.03 × 10^-19 J

Explanation:

The energy, E, of a photon of light can be calculated by using the formula:

E = hv

Where; E is energy in Joules,

h is Planck's constant {6.626×10^−34J}

v is frequency of light

For this question, the wavelength (λ) is given, not the frequency (v).

Hence, we use;

v= c/λ

Where v= frequency, c= speed of light (3×10^8m/s), λ= wavelength (657nm)

657nm = 657 × 10^-9m

v = 3×10^8/657 × 10^-9

v = 3/657 × 10^(8--9)

v = 0.00456 × 10^17

v = 4.56 × 10^14

Since frequency (v) = 4.56 × 10^14;

E = hv

E = 6.626×10^−34 × 4.56 × 10^14

E = 30.21 × 10^(-34+14)

E = 30.21 × 10^-20

E = 3.021 × 10^-19

Therefore, the energy of the photon of light is 3.02 × 10^-19 J

Answer:

period number

Answer:

Period number

Explanation:

Period number is the answer.

Hope this is right!

Answer:

15.99937 is the value of this question answer

Answer:

C 14

Explanation:

Silicon atom has 14 protons. Given that a positive and a negative neutralize each other you need 14 electrons to neutralize the 14 protons.

Answer:

1.69×10²⁹ molecules.

Explanation:

The following data were obtained from the question:

Mass of Ammonia (NH3) = 5.25 tons

Molecules of Ammonia (NH3) =.?

Next, we shall convert 5.25 tons to grams (g). This can be obtained as follow:

1 ton = 907184.74 g

Therefore,

5.25 ton = 5.25 ton × 907184.74 g / 1 ton

5.25 ton = 4762719.885 g

Therefore, 5.25 tons is equivalent to 4762719.885 g

Finally, we shall determine the number of molecules of ammonia, NH3 in 4762719.885 g. This can be obtained as follow:

From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ molecules. This implies that 1 mole of ammonia, NH3 also contains 6.02×10²³ molecules.

1 mole of ammonia, NH3 = 14 + (3x1) = 14 + 3 = 17 g

17 g of ammonia, NH3 contains 6.02×10²³ molecules.

Therefore, 4762719.885 g of ammonia, NH3 will contain = (4762719.885 × 6.02×10²³) / 17 = 1.69×10²⁹ molecules.

From the calculations made above,

5.25 tons (4762719.885 g) of ammonia, NH3 contains 1.69×10²⁹ molecules.

Answer:

Ionic bonding is the complete transfer of valence electron(s) between atoms. It is a type of chemical bond that generates two oppositely charged ions. In ionic bonds, the metal loses electrons to become a positively charged cation, whereas the nonmetal accepts those electrons to become a negatively charged anion

Explanation:

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Answer:

Atomic theory is the scientific theory that matter is composed of particles called atoms.

isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number.

to calculate the atomic mass of a single atom of an element, add up the mass of protons and neutrons.

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Explanation: