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Which of the following is not a good indication that a chemical change has occurred?
A. The formation of gases
B. A change in color
C. A scratched surface
D. The release heat or light​

The intial temperature : 59.865 °C

Heat added :

Q = m . c . ΔT

Q = heat, J  

m = mass, g  

c = specific heat, joules / g ° C  

∆T = temperature difference, ° C / K  

[tex]\tt 305=94.8\times 0.128\times (85-t_1)\\\\85-t_1=25.135\\\\t_1=59.865^oC[/tex]

The chemical equation is said to be balanced if the number of atoms in the reactants and products is the same

Equation balanced ⇒ total number of atoms in reactants(on the left)= total number of atoms in products(on the right)

H₂+O₂---> H₂O

Reactants : H₂, O₂

Products : H₂O

not balanced

H₂O₂ ---> H₂O+O₂

Reactants : H₂O₂

Products : H₂O, O₂

not balanced

Na+O₂ ---> Na₂O

Reactants : Na, O₂

Products :  Na₂O

not balanced

N₂+H₂ ---> NH₃

Reactants : N₂, H₂

Products :  NH₃

not balanced

P₄+O₂---> P₄O₁₀

Reactants : P₄, O₂

Products :  P₄O₁₀

not balanced

Fe+H₂O ----> Fe₃O₄ + H₂

Reactants : Fe, H₂O

Products :  Fe₃O₄

not balanced

Answer:

Theoretical yield = 16.76 g

Percent yield = 87%

Explanation:

Given data:

Mass of iron oxide = 23.5 g

Theoretical yield of iron = ?

Actual yield of iron = 14.5 g

Percent yield of iron = ?

Solution:

Chemical equation:

2Fe₂O₃ + 3C     →  4Fe + 3CO₂

Number of moles of iron oxide:

Number of moles = mass/molar mass

Number of moles = 23.5 g/ 159.69 g/mol

Number of moles = 0.15 mol

Now we will compare the mole of iron oxide with iron metal.

                      Fe₂O₃         :            Fe

                         2              :              4

                      0.15            :          4/2×0.15 = 0.3

Mass of iron:

Mass = number of moles × molar mass

Mass = 0.3 mol × 55.85 g/mol

Mass = 16.76 g

Percent yield:

percent yield = (actual yield / theoretical yield)× 100

Percent yield = (14.5 g / 16.76 g) × 100

Percent yield = 0.87 × 100

Percent yield = 87%

Answer:

I tried the answer above and it’s correct

Explanation:

Answer:

fewer collisions occur between particles or lowering the temperature

Explanation:

Answer:

B - What we change

Explanation:

Dependent Variable - What we measure

Control Variable - what stays the same

Conclusion - what we conclude

Hope this can Help!

:D

Answer:

A change in the shape of a substance

Explanation:

Because when ths shape of a sunstance changes , its physical appearance changes .A physical change is a change to the physical—as opposed to chemical—properties of a substance. They are usually reversible. The physical properties of a substance include such characteristics as shape (volume and size), color, texture, flexibility, density, and mass.

Answer:

The screw with 10 wraps is the correct answer

Explanation:

The screw with 6 wraps would create a strong hold.

The strongest member of the family of wood screws is a lag screw. It is a reliable and sturdy fastener that frequently has a square head or an externally powered hex drive.

In general, lag screws are significantly stronger and heavier than standard wood screws. They have a tapered point and coarse threads.

Thus, The screw with 6 wraps would create a strong hold.

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# SPJ5

Explanation:

Glass is not a liquid in the strictest sense of the word. But it is also not a standard solid. The chemistry of glass is complex and research is ongoing, but the current consensus is that glass is a phase of matter all its own, known as an "amorphous solid". Scientists refer to any amorphous solid as a "glass". Glass transitions are highly complex and cannot be treated in the same way as traditional phase transitions.

Answer:

It's a liquid state before its cooled.

Answer:

Alkali Metals

Explanation:

#1: A covalent bond

#2 False

#3True

Answer:

Warm and cold ocean currents can affect the climate of an area along the coast if the winds blow in from the ocean. Warm ocean currents heat the air above the water and carry the warm air to the land, increasing the temperature of the coastal region.

Explanation:

Ocean currents are important to coastal regions for a number of reasons.

Distribute heat. Ocean currents distribute heat around the globe, which helps to moderate the climate in coastal regions. For example, the Gulf Stream brings warm water from the Gulf of Mexico to the coasts of Europe, which helps to keep Europe's climate warmer than it would be otherwise.

Transport nutrients. Ocean currents transport nutrients from the ocean's depths to the surface, which supports marine life. For example, the California Current brings nutrients from the deep ocean to the surface, which supports a rich marine ecosystem off the coast of California.

Diversify marine life. Ocean currents help to diversify marine life by transporting different species to different parts of the ocean. For example, the Kuroshio Current brings warm water from the western Pacific Ocean to the eastern Pacific Ocean, which has helped to diversify the marine life in this region.

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#SPJ6

Answer:

The element hydrogen has the simplest atoms, each with just one proton and one electron. The proton forms the nucleus, while the electron orbits around it.

Explanation:

Answer:

132g/mol

Explanation:

Given compound:

   C₆H₁₂O₆

Molecular mass of the compound.

 This is the sum of the atomic masses of the given elements in the compound;

  C = 12

  H  = 12

  O = 6

Molecular mass = 6(12) + 12(1) + 6(16) = 180g/mol

Answer:

Explanation:

Photosynthesis is important to living organisms because it is the number one source of oxygen in the atmosphere. Without photosynthesis, the carbon cycle could not occur, oxygen-requiring life would not survive and plants would die. ... The importance of photosynthesis in our life is the oxygen it produces

Answer:

turns blue litmus red

reacts with metal

increase hydrogen concentration

Answer:

Explanation:

before the reaction you have K=2 and Cl=4

after the reaction K=2 and Cl=2 so it does not follow the law of conservation

Explanation:

The flame test is used to visually determine the identity of an unknown metal or metalloid ion based on the characteristic color the salt turns the flame of a Bunsen burner. The heat of the flame excites the electrons of the metals ions, causing them to emit visible light

Answer: C

Explanation:

There are 761.4 grams of CS2 in 10.00 mol.

To calculate the amount of grams present in a given amount of moles, the molar mass of the substance must be used, as follows:

                                        [tex]m = MM \times mol[/tex]

In this way, just perform the following operation:

                                          [tex]m = 76.14 \times 10[/tex]

                                         [tex]m = 761.4 grams[/tex]

Thus, there are 761.4 grams of CS2 in 10 mol of the substance.

Learn more about mole calculation in: brainly.com/question/15693285

Answer:

Explanation:

by stoichiometry

nNH3/2=nH2/3

0.25/2=nH2/3

nH2=0.25×3/2

nH2=0.375 mol

so its 0.38 mol

Answer:

I have this quiz rn I will try 0.38 if it is right I’ll edit this and say that

Explanation:

Answer:

A. ✔️Substitution

B. ✔️Insertion

C. ✔️Deletion

Explanation:

In A, the type of mutation that is shown is Substitution. In B, the type of mutation shown is Insertion and in C, the type of mutation shown is Deletion.

Mutation refers to the change in the DNA sequence. This occurs in an organism. In gene mutation, the structure of DNA molecule changes and produces a different allele of a gene. While in chromosome mutation, there is the change in the structure or number of the whole chromosomes in a particular cell.

Actually, mutations can take place both in prokaryotic cell and in eukaryotic cell.

In genetics, there are: Substitution, Insertion and Deletion mutations.

Substitution mutation is an exchange of one base for another. Insertion mutation is simply addition of one or more nucleotide pairs in a DNA sequence while Deletion mutation refers to the situation in which a sequence of DNA is left out when there is DNA replication.

Answer:

A. Substitution

B. Insertion

C. Deletion

Explanation:

A. There is a replacement in C G there is A T.

B. There is one more base.

C. There are 8 base there should be 9.

Answer: 7 neutrons

Explanation: Atomic number refers to the number of protons in the nucleus of the atom. Also you can treat atomic mass as how many particles (protons and neutrons) are in the nucleus of the atom. So for this problem:

14 particles - 7 protons = 7 neutrons (and we know all that's left over is neutrons because we subtracted all the protons)

Answer:

there are two significant figures

Explanation:

Answer:

there are two

Explanation:

because the zeros dont count

Hello!

[tex]\large\boxed{167g}[/tex]

Looking at the balance, we see that:

The middle beam reads 100g.

The top beam reads 60g.

The bottom beam reads 7g.

Add all of the numbers together to get the total mass:

100 + 60 + 7 = 167g.

The mass of the object is 167 grams.

Explanation:

Given :

Readings of all the scales of three beams of the triple beam balance of an object.

To find :

The mass of object whose reading on triple beam balance is given.

Solution:

Middle beam reader at 100 grams

Front beam reader at 7 grams

Farther beam reader at 60 grams

The mass of object:

[tex]100 grams + 7 garms + 60 grams = 167 grams[/tex]

The mass of the object is 167 grams.

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Answer:

CO2

Explanation:

Answer:

0.92moles

Explanation:

Given reaction:

              2Fe + 3Cl₂ →  2FeCl₃

Mass of FeCl₃  = 100g

Unknown:

Number of moles of Cl₂  needed = ?

Solution:

To solve this problem, we work from the known specie to the unknown.

From the mass of the FeCl₃ given, we can solve for the number of moles of the unknown.

  Number of moles  = [tex]\frac{mass}{molar mass}[/tex]  

  Molar mass of  FeCl₃ = 56 + 3(35.5) = 162.5g/mol

   Number of moles  = [tex]\frac{100}{162.5}[/tex]  = 0.62mole

From the reaction expression;

           2 mole of FeCl₃ is produced from 3 moles of  Cl₂  

           0.62 mole of FeCl₃ will be produced from [tex]\frac{0.62 x 3}{2}[/tex]   = 0.92mole

The number of moles of Cl₂  = 0.92moles

Answer:

Radioactive elements

Stable

Explanation:

Radioactive elements that have a longer half-life are more stable than those that a shorter half-life.

Half-life is the time taken for half of a radioactive element to decay by half of its original composition.

Now, if a substance have a long half-life, it is more stable and takes time to break down. For atoms with a short life, they are highly unstable and breaks down readily and easily.

Answer:

e

Explanation:

it's in the index fossil range

Answer:

Explanation:

In marine strata, index fossils that are commonly used include the single-celled Protista with hard body parts and larger forms such as ammonoids. In terrestrial sediments of the Cenozoic Era, which began about 65.5 million years ago, mammals are widely used to date deposits.

Answer:

Explanation:

The acceleration of an object given it's mass and the force acting on it can be found by using the formula

[tex]a = \frac{f}{m} \\ [/tex]

f is the force

m is the mass

From the question we have

[tex]a = \frac{47}{7} \\ = 6.714285...[/tex]

We have the final answer as

Hope this helps you

Answer:

1

Explanation: