Helen knit a total of 175 centimeters of scarf over 35 nights. How many nights will Helen have to spend knitting in order to knit a total of 180 centimeters of scarf? Solve using unit rates.

Answer:

Hello your question is incomplete attached below is the complete question

answer : attached below

Explanation:

The design is attached below

The reagents are : H₂SO₄, H₂O,  HBr,  NaOCH₂CH₃

For the scheme = 1.NaOH,H2O   2. H₃O+3,   heat,  SOCl₂,  Et3N

The number of moles of helium (He) needed to make the balloon rise is 0.043 moles.

The number of moles of a gas can be calculated using the following expression:

V₁/n₁ = V₂/n₂

Where;

Avogadro’s law to predict what will happen to the volume of a sample of gas as we change the number of moles. Because V/n is a constant for any given sample of gas (at constant P and T).

At constant temperature and pressure the volume of a gas is directly proportional to the number of moles of gas.

0.46/0.0226 = 0.865/n

20.3539823n = 0.865

n = 0.043 moles

Therefore, 0.043 moles is the number of moles of the gas when the balloon rises.

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Answer:

neutrons = 20

Explanation:

No. of Neutrons = Mass No. - Atomic No

= 39 - 19

=20

Answer:

1) What is the element? Potassium

2) how many neutrons does it have? 20

3) If it is a neutral atom how many electrons does it have?​ 39

Please mark as brainliest if answer is right

Have a great day, be safe and healthy  

Thank u  

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Mass can be calculated by using moles which can be further calculated from multiplication of Molarity to volume. Therefore, the molarity of the HCl solution is 3M. the correct option is option C.

Molarity can be calculated by dividing  number of moles of solute by volume of solution in litre. Molarity is affected by temperature. Its unit is mole/litre. It measure the concentration of any solute in a solution.

Other concentration terms are molality, normality and mole fraction. Molarity can be used to find out the ionic strength of any solution

Mathematically,

2HCl + Ca(OH)[tex]_2[/tex] [tex]\rightarrow[/tex] CaCl[tex]_2[/tex] + 2H[tex]_2[/tex]O

Molarity of HCL× Volume of HCL=Molarity of Ca(OH)[tex]_2[/tex] ×Volume of  Ca(OH)[tex]_2[/tex]

Molarity of HCL× 1.00 L=1.50 M× 2.00 L

Molarity =3M

Therefore, the molarity of the HCl solution is 3M. the correct option is option C.

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Answer:

4.76×10¯⁵ cm

Explanation:

We'll begin by converting 476 nm to m. This can be obtained as follow:

1 nm = 1×10¯⁹ m

Therefore,

476 nm = 476 nm × 1×10¯⁹ m / 1 nm

476 nm = 4.76×10¯⁷ m

Finally, we shall convert 4.76×10¯⁷ m to cm. This can be obtained as follow:

1 m = 100 cm

Therefore,

4.76×10¯⁷ m = 4.76×10¯⁷ m × 100 cm / 1 m

4.76×10¯⁷ m = 4.76×10¯⁵ cm

Thus,

476 nm = 4.76×10¯⁵ cm

Answer:

Reactants collide to form a transition state.

Explanation:

So sorry if I’m wrong but I feel this is right

To solve such this we must know the concept of chemical reaction. The correct option is option B that is atoms in one compound switch places with atoms in another compound.

Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved.

There are so many types of chemical reaction reaction like combination reaction, double displacement reaction, combustion reaction, displacement reaction. "Reactants collide to form a transition state" describes the first part of a chemical reaction.

Therefore "Reactants collide to form a transition state" describes the first part of a chemical reaction. The correct option is option B.

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Answer:

110k because 2 x 110 =220

Answer:

I think the answer is 14 I am not sure

Answer:

3.4

373.4

.45.=2

46.=3 .6.2=4

Answer:

umm use a calculator ok bye

Answer:

Explanation:

To break apart a molecule of H2So4 is much higher than HCl although HCl is an ionic bond it is only bonded to one hydrogen. While H2So4 is bonded to two of them, aswell as its structure being much more complex. The energy to break Ba(h)2 is equal in both.

My exploration in one specific element as well as the sharing of the historical context and modern day application will be focused in the element Carbon. The essay is written below

Carbon was discovered by the ancient Egyptians, and it gets its name from the Latin word "carbo," which means "charcoal."

Carbon is a nonmetal that is located in Group 14 of the periodic table. It has a unique ability to form a wide variety of chemical compounds, which is one of the reasons it is so important in modern chemistry. Carbon has four valence electrons, which allows it to form stable chemical bonds with other elements.

Carbon is a chemical element that is found in all living things. It is a key component of proteins, DNA, and other essential biomolecules. Carbon can exist in several different forms, including graphite, diamond, and various forms of carbon-based compounds called organic molecules.

Carbon has many important implications for society. It is used as a fuel to produce energy, and it is also a key ingredient in the production of steel and other metals. Carbon is also an essential component of many plastics and other synthetic materials. However, carbon can also have negative impacts on the environment, as the burning of fossil fuels releases carbon dioxide into the atmosphere, contributing to climate change.

Carbon has many practical applications, including its use as a fuel, a structural material, and a chemical feedstock. However, carbon can also be hazardous in certain situations. For example, inhaling carbon monoxide can be deadly, and carbon dust can be explosive. Carbon is commonly encountered in many different forms, including coal, oil, and natural gas.

Personally, I think that carbon is a very interesting element with a wide range of important applications. It is fascinating to consider the role that carbon plays in the biology of living organisms, as well as its practical uses in industry and technology.

Some questions for my classmates might include: What are some other interesting properties of carbon that you have learned about? Can you think of any examples of how carbon is used in your everyday life? Do you think that the benefits of carbon outweigh the potential drawbacks?

One peer-reviewed resource that I found informative is "The Many Forms of Carbon," an article published in the journal Chemical & Engineering News. (Citation: "The Many Forms of Carbon." Chemical & Engineering News, vol. 95, no. 39, 2017, pp. 38-54.)

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Answer:

a

Explanation:

The formation of ion occurs when an atom that is said to be neutral gains or losses electrons.

At the time it gains electrons, it is regarded that a negative ion (anion) is formed.

When it loses electron, it is regarded that a positive ion (cation) is formed.

Atomic number = No of protons and electrons occurring in a neutral atom.

Given that:

Protons = 14

electron = 18

Net Charge = no of proton - no of electron

= 14 - 18

= -4

Mass number = 14 + 15 = 29

So, the chemical symbol = [tex]Si^{-4}[/tex]

For ion with

27 proton, 32 neutrons and 25 electrons

Net charge = 27 - 25

= +2

Mass number = 27 + 32 = 59

Thus, the chemical symbol = [tex]Co^{+2}[/tex]

Answer:

A

Explanation:

Solute is what is being dissolved.

Solute is cocoa powder when we make a cup of hot chocolate ,therefore option (a) is correct.

A solute is a substance that is dissolved in a solvent to form a solution.

The concentration of a solute in a solution is a measure of how much of the solute is dissolved in the solvent.

Characteristics of solute -:

Solute is cocoa powder when we make a cup of hot chocolate ,hence option (a) is correct.

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Answer: C) All of the rabbits in a forest, as well as their predators and food plants

Explanation:

The community refers to all living things in a certain area including plants and animals. If the given area is a forest therefore, the rabbit being a living thing, as well as its predators and the plants that it relies on will be considered the community.

This is not unlike a human community where everyone in a given area is considered to be part of the community.

Answer:

C

Explanation:

I got this question on an edusmart.

Answer:

Mass of CaCl2 = 4.1625 grams

Explanation:

We will recall that:

For solution: Molarity = [tex]\dfrac{moles \ of \ solute }{volume \ of \ solution (L)}[/tex]

[tex]1.5 = \dfrac{moles}{0.025 }[/tex]

Moles = 0.0375 moles

Mass = no of moles × molar mass(MM)

Molar mass of CaCl2 = 111 g/mol

Mass = 0.0375 mol × 111 g/mol

Mass of CaCl2 = 4.1625 grams

-33⁰C

Explanation:

Charles Law states V/T initial = V/T final

T must be in Kelvin.

100/300 = 80/x

(27⁰C + 273 = 300

100x = (300)(80)

100x = 24,000

x = 240⁰K

240 - 273 = -33⁰C

The nonmetals in the Groups 16 and 17 gain electrons making them an anion.

The nonmetals of group 16 are made up of Oxygen, Sulfur, and Selenium whereas group 17, also called the halogen group is made up of Fluorine, Chlorine, etc.

The further right we go in the periodic table, the atomic size decreases. Due to the increase in the number of protons, the electrons are more tightly bound and the atom shows strong attraction to electrons.  

The gain of additional electrons helps in the completion of octets for the atoms further making their configuration stable, and more alike to that of the noble gases.

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The vapor pressure at 49.5 °C is:

DP = 48.8 kJ/mol / 8.314 J/mol*K * (1/451.0 K - 1/322.65 K) * 49.5

DP = 0.24 torr (approx)

The vapor pressure of benzaldehyde at 49.5°C is approximately 0.24 torr.

The heat of vaporization (ΔHvap) and the normal boiling point (Tb) can be used to determine the vapor pressure of a liquid at a given temperature using the Clausius-Clapeyron equation. The Clausius-Clapeyron equation states that the change in vapor pressure (DP) with temperature (DT) is directly proportional to the heat of vaporization (ΔHvap) and inversely proportional to the absolute temperature (T) in kelvin.

DP/DT = ΔHvap / R * (1/T)

where R is the gas constant.

We can use this equation to solve for the vapor pressure of benzaldehyde at 49.5°C.

First, convert 49.5°C to kelvin:

T = 49.5°C + 273.15 = 322.65 K

Next, we need to use the Clausius-Clapeyron equation to solve for vapor pressure at a temperature T and the normal boiling point Tb:

DP/DT = ΔHvap / R * (1/T) = ΔHvap / R * (1/Tb - 1/T)

DP = ΔHvap / R * (1/Tb - 1/T) * DT

The vapor pressure at 49.5 °C is:

DP = 48.8 kJ/mol / 8.314 J/mol*K * (1/451.0 K - 1/322.65 K) * 49.5

DP = 0.24 torr (approx)

The vapor pressure of benzaldehyde at 49.5°C is approximately 0.24 torr.

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The vapor pressure of the benzaldehyde is  196 torr.

We know that the vapor pressure would have to do with the ease that we can use to convert the substance that is in question from liquid to gas. When we have two substances that are at different temperatures than we have;

ln(P2/P1) = -ΔH/R(1/T1 - 1/T2)

P2 = final pressure

P1 = initial pressure

R = gas constant

T1 = initial temperature

T2 = final temperature

Thus;

ln(P2/1) = -48.8* 10^3/8.314(1/451 - 1/322.5)

lnP2 = -5869.6(0.0022 - 0.0031)

lnP2 = 5.28

P2 =e^5.28

P2 = 196 torr

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Answer: what is the answer

Explanation:

I need it nowwww

Natural radioactive elements are those that spontaneously radiate in nature and have an atomic number between 82 and 92. In dirt, air, water, rocks, plants, food, uranium—a radioactive element—can be discovered.

When an element's atoms contain excess neutrons or protons, the extra energy produced in the nucleus causes the atom to lose its equilibrium or become unstable. if and how radioactive particles can become stable. Radiation is produced by radioactive atoms' unstable nuclei.

Compared to beta and gamma particles, alpha particles represent the most dangerous internal threat. The most hazardous methods of exposure to radioactive elements that release alpha and beta radiation are ingestion, inhalation, absorption, and injection. Gamma radiation is the outside hazard that causes the most damage.

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Sublevels are indicated by letters s, p, d, and f.

How do write Electronic configuration?

Electron configurations have a standard notation that tells you the principle energy levels and sublevels that electrons occupy. here is Sulphur:

The atomic number of Sulphur is 16.

the electronic configuration of Sulphur is 1s2 2s2 2p6 3s2 3p4.

The 4s sublevel has lower energy than the 3d sublevel,

so, it fills next.

One orbital can house a maximum of two electrons, and there are four different types of orbitals (s, p, d, and f). More electrons can be held in the p, d, and f orbitals since they contain various sublevels. According to its location on the periodic table, each element's electron configuration is distinct.

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Atoms are made up of a very tiny, positively charged nucleus that is encircled by a sea of negatively charged electrons. Despite often being less than a tenth of an atom's size, the nucleus makes up more than 99.9% of the atom's mass.

The term "atomic structure" describes the structure of an atom, which has a nucleus (centre) that contains both protons (positively charged) and neutrons (neutral). The centre of the nucleus is circled by the negatively charged electrons.

Positively charged protons, negatively charged electrons, and neutral neutrons make up the three types of subatomic particles that make up an atom. Nearly equal in mass, protons and neutrons are found in the dense nucleus of the atom.

Thus, Atoms are made up of a very tiny, positively charged nucleus that is encircled by a sea of negatively charged electrons.

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Answer:

A. one potassium and one iodine

Explanation:

K is a metal and I is a nonmetal, so K will lose electrons to form a cation and I will gain electrons to form an anion. Together, they will be bonded through an ionic bond. To determine how many electrons they gain or lose and how many atoms are in the chemical formula, we need to consider the octet's rule: an atom will gain, lose, or share electrons until it has 8 electrons in its valence shell.

We need 1 K⁺ and 1 I⁻ to form the neutral salt KI.

Answer:

4.44 moles

Explanation:

first u have to change the units into dm cube.

cm cube÷1000=dm cube

185cmcube÷1000= 0.185dm cube

24dm cube= 1 mole(formula)

0.185dm cube × 24dm cube=4.44 moles

Answer:

Property of an element by virtue of which it exists in two or more forms which differ only in their physical properties is known as allotropy. Allotropes are the different physical forms in which the element can exist. Allotropes are different physical forms of the same element.

Also-

Allotropes are different forms of the same element in the molecular level. Isotopes are different forms of atoms of the same chemical element. The key difference between allotropes and isotopes is that allotropes are considered at the molecular level, whereas isotopes are considered at the atomic leve

Explanation:

~Hope this helps~

The global climate was colder than normal from 1650 to 1700. This conclusion is most likely correct. Therefore, option A is correct.

Global climate refers to how heat and precipitation are distributed over a lengthy period of time on Earth's surface. The average temperature of the planet is kept at roughly 60°F (16°C) by heat from the sun, which is within the range required for biological life and the preservation of the planet's liquid water reserves.

Global climate change is the collective term for all the Earth's average long-term changes. Along with changing precipitation patterns and higher temperatures, these also include the consequences of global warming, such as: rising sea levels alpine glaciers are thinning.

Thus, option A is correct.

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Your question is incomplete probably your question was

The graph below shows the averaged sunspots from 1610 to 2007. The graph shows sunspot number on the y axis and years 1600, 1650, 1700, 1750, 1800, 1850, 1900, 1950, and 2000 on the x axis. The graph rises and falls in a cyclic order in gaps of approximately 10 years. The number of sunspots observed in 1610 was 40, in 1650 it was 5, in 1700 it was 10, in 1750 it was 90 and the number of sunspots in 1800 was 50. The number of sunspots observed in 1850 was 130 and the number of sunspots in 1900 was 10. The number of sunspots observed in 1950 was 150 and the number of sunspots observed in 2000 was 30. Based on the graph, which of these conclusions is correct? Some of the previously warm regions became colder from 1650 to 1700. Some of the previously cold regions became warmer from 1600 to 1700. Some of the previously warm regions became warmer from 1610 to 1700. Some of the previously cold regions became colder from 1900 to 1950.

Answer:

Capacity is the amount of liquid a container can hold. Mass is how much space an object takes up.

Explanation:

All the others are incorrect.