Which substances have AH = 0 kJ/mol

Answer:

the dots on a lewis structure represent valence electrons so they are the amount of valence electrons in the lewis structures atom

Answer:

Advantages: More land has been made available for development. More buildings and infrastructure can be built, and also for other reasons.

Disadvantages: Much greenery has been removed in order for the land needed. Land reclamation can be damaging to corals and marine life. Corals are usually moved to another place when land is to be reclaimed. The corals might not be able to survive in that certain habitat, and thus die out. In some countries, where the project is large-scale, they do not even bother to re-plant the corals elsewhere, instead just reclaim the land on their habitat, causing them to die out immediately. Marine life, such as fishes, might not have enough food after the underwater plantations are destroyed due to reclamation of land. This applies to the food chain. The waters might also be polluted from the soil used to reclaim land, causing the fishes to die and blocking out sunlight, depriving the underwater plants of growth. Marine habitats are also destroyed, as mentioned earlier; therefore, the marine creatures would be forced to move to another new habitat. Some might not be able to adapt, and thus die out. Some would just die without even finding a new habitat, as they cannot move long distances in water. Of course, the reasons and examples look tempting to us humans, but marine life is life too! We should try to protect is as much as possible, instead of just focusing on the advantages.

Answer:

7.71 atm

Explanation:

Given the following data:

[tex]V = 5 L[/tex]

[tex]n_{He} = 3 mol[/tex]

[tex]n_{H_2} = 4 mol[/tex]

[tex]p_1 = 9 atm[/tex]

[tex]T = const[/tex]

According to the ideal gas law, we know that the product between pressure and volume of a gas is equal to the product between moles, the ideal gas law constant and the absolute temperature:

[tex]pV = nRT[/tex]

Since the temperature and the ideal gas constant are constants, as well as the fixed container volume of 5 L, we may rearrange the equation as:

[tex]\frac{p}{n}=\frac{RT}{V}=const[/tex]

This means for two conditions, we'd obtain:

[tex]\frac{p_1}{n_1}=\frac{p_2}{n_2}[/tex]

Given:

[tex]p_1 = 9 atm[/tex]

[tex]n_1 = n_{initial total} = n_{He} + n_{H_2} = 3 mol + 4 mol = 7 mol[/tex]

[tex]n_2 = n_{final total} = n_{He} + n_{H_2} = 3 mol + 4 mol + 2 mol = 9 mol[/tex]

Solve for the final pressure:

[tex]p_2 = p_1\cdot \frac{n_2}{n_1}[/tex]

Now, according to the Dalton's law of partial pressures, the partial pressure is equal to the total pressure multiplied by the mole fraction of a component:

[tex]p_{H_2}=\chi_{H_2}p_2[/tex]

Knowing that:

[tex]p_2 = p_1\cdot \frac{n_2}{n_1}[/tex]

And:

[tex]\chi_{H_2}=\frac{n_H_2}{n_2}[/tex]

The equation becomes:

[tex]p_{H_2}=\chi_{H_2}p_2=p_1\cdot \frac{n_2}{n_1}\cdot \frac{n_H_2}{n_2}=p_1\cdot \frac{n_H_2}{n_1}[/tex]

Substituting the variables:

[tex]p_{H_2}=9 atm\cdot \frac{4 mol + 2 mol}{7 mol}=7.71 atm[/tex]

Answer:

Wegener discovered that the Appalachian Mountains of the eastern United States, for instance, were geologically related to the Caledonian Mountains of Scotland. Pangaea existed about 240 million years ago. By about 200 million years ago, this supercontinent began breaking up

Answer:

What evidence did Wegner use to develop his hypothesis? = Alfred Wegener suggested that continental drift occurred as continents cut through the ocean floor, in the same way as this icebreaker plows through sea ice. Wegener put his idea and his evidence together in his book The Origin of Continents and Oceans, first published in 1915.

Continental drift describes one of the earliest ways geologists thought continents moved over time. Today, the theory of continental drift has been replaced by the science of plate tectonics.  

The theory of continental drift is most associated with the scientist Alfred Wegener. 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. He called this movement continental drift.  

Pangaea

Wegener was convinced that all of Earth’s continents were once part of an enormous, single landmass called Pangaea.  

Wegener, trained as an astronomer, used biology, botany, and geology describe Pangaea and continental drift. For example, fossils of the ancient reptile mesosaurus are only found in southern Africa and South America. Mesosaurus, a freshwater reptile only one meter (3.3 feet) long, could not have swum the Atlantic Ocean. The presence of mesosaurus suggests a single habitat with many lakes and rivers.

Wegener also studied plant fossils from the frigid Arctic archipelago of Svalbard, Norway. These plants were not the hardy specimens adapted to survive in the Arctic climate. These fossils were of tropical plants, which are adapted to a much warmer, more humid environment. The presence of these fossils suggests Svalbard once had a tropical climate.

Finally, Wegener studied the stratigraphy of different rocks and mountain ranges. The east coast of South America and the west coast of Africa seem to fit together like pieces of a jigsaw puzzle, and Wegener discovered their rock layers “fit” just as clearly. South America and Africa were not the only continents with similar geology. Wegener discovered that the Appalachian Mountains of the eastern United States, for instance, were geologically related to the Caledonian Mountains of Scotland.  

Pangaea existed about 240 million years ago. By about 200 million years ago, this supercontinent began breaking up. Over millions of years, Pangaea separated into pieces that moved away from one another. These pieces slowly assumed their positions as the continent we recognize today.

Today, scientists think that several supercontinents like Pangaea have formed and broken up over the course of the Earth’s lifespan. These include Pannotia, which formed about 600 million years ago, and Rodinia, which existed more than a billion years ago.

Tectonic Activity

Scientists did not accept Wegener’s theory of continental drift. One of the elements lacking in the theory was the mechanism for how it works—why did the continents drift and what patterns did they follow? Wegener suggested that perhaps the rotation of the Earth caused the continents to shift towards and apart from each other. (It doesn't.)

Today, we know that the continents rest on massive slabs of rock called tectonic plates. The plates are always moving and interacting in a process called plate tectonics.  

The continents are still moving today. Some of the most dynamic sites of tectonic activity are seafloor spreading zones and giant rift valleys.  

In the process of seafloor spreading, molten rock rises from within the Earth and adds new seafloor (oceanic crust) to the edges of the old. Seafloor spreading is most dynamic along giant underwater mountain ranges known as mid-ocean ridges. As the seafloor grows wider, the continents on opposite sides of the ridge move away from each other. The North American and Eurasian tectonic plates, for example, are separated by the Mid-Atlantic Ridge. The two continents are moving away from each other at the rate of about 2.5 centimeters (1 inch) per year.  

Rift valleys are sites where a continental landmass is ripping itself apart. Africa, for example, will eventually split along the Great Rift Valley system. What is now a single continent will emerge as two—one on the African plate and the other on the smaller Somali plate. The new Somali continent will be mostly oceanic, with the Horn of Africa and Madagascar its largest landmasses.

The processes of seafloor spreading, rift valley formation, and subduction (where heavier tectonic plates sink beneath lighter ones) were not well-established until the 1960s. These processes were the main geologic forces behind what Wegener recognized as continental drift.

Answer:

There ain't enough info in the question to answer but, I can say that reactants were there before the reaction, but products were produced by the reaction.

Explanation:

I don't really know how to answer this.

Radioactive

A substance that gives out radiation all the time is unstable, therefore called radioactive.

I checked the answer myself and got it correct so i hope that this helps. (✿◡‿◡)

The statement, that describes ionizing radiation is emitted all the time is by "radioactive sources."

Ionizing radiation is the radiation released by unstable nuclei because it can dislodge outer electrons from atoms, forcing them to form ions as it passes through matter. This radiation generates energy from either natural or man-made sources.

Ionizing radiation is a type of energy that atoms emit as electromagnetic waves or particles. People are exposed to ionizing radiation from both natural sources, such as soil, water, and vegetation, and man-made ones, such as x-rays and medical gadgets. Ionizing radiation sources include radioactive materials that emit radiation all the time.

Hence the correct answer is radioactive sources.

Learn more about ionizing radiation here

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Answer:

Most common insulation materials work by slowing conductive heat flow and--to a lesser extent--convective heat flow. Radiant barriers and reflective insulation systems work by reducing radiant heat gain. To be effective, the reflective surface must face an air space.

Explanation:

To be effective, the reflective surface must face an air space.

Answer:

A. Is independent of other energy influences  

Explanation:

Nuclear decay occurs at a constant rate. The rate of decay is independent of temperature.

B, C, and D are wrong.  The decay rate cannot be sped up or slowed down at ordinary temperatures.

"The correct answer is C. can be sped up upon cooling.

Nuclear decay is a process that occurs when an atomic nucleus emits radiation in the form of particles or electromagnetic waves. This process is random and is not influenced by external factors such as temperature, pressure, or chemical state. The rate of decay of a radioactive substance is characterized by its half-life, which is the time required for half of the radioactive atoms in a sample to decay.

 The half-life is a fundamental property of a radioactive isotope and is not affected by external conditions. Therefore, the statements A, B, and D are incorrect:

 A. Nuclear decay is independent of other energy influences, meaning that external energy sources or conditions do not affect the rate of decay.

 B. Nuclear decay cannot be sped up upon heating. The decay rate is intrinsic to the isotope and does not change with temperature.

 D. Nuclear decay cannot be sped up at room temperature. Room temperature does not have any significant effect on the decay rate.

 C. However, it is worth noting that certain nuclear reactions, not the decay itself, can be influenced by temperature. For example, nuclear fusion reactions, which are different from decay processes, can be affected by temperature because they involve the combining of light atomic nuclei to form heavier ones, and higher temperatures can provide the necessary energy to overcome the repulsive forces between positively charged nuclei. In the context of nuclear decay, the statement ""can be sped up upon cooling"" is not accurate in the sense that cooling does not affect the decay rate. The decay rate remains constant regardless of temperature changes. Therefore, the correct statement should be that nuclear decay is independent of temperature changes, and none of the options provided accurately describe the influence of temperature on nuclear decay.

 In summary, the decay of a radioactive nucleus is a random process with a constant probability per unit time, and the rate of decay is not affected by external conditions such as temperature. The correct answer to the question is that nuclear decay cannot be sped up or slowed down by any known external means, including heating, cooling, or maintaining the sample at room temperature."

Answer:

b) 1,1,2

Explanation:

                   2 - Cl - 2

                   6 - O - 6

                   2 - H - 2

by semireactions, the chloride ion (Cl) is balanced with HClO3 and the oxygen is balanced with water:

Cl2O5 + H2O → 2 HClO3

Answer:

732.0601 mmHg

Explanation:

Given data:

Pressure = 97.6 KPa

Given pressure in mmHg = ?

Solution:

Kilo pascal and millimeter mercury both are units of pressure.

Kilo pascal is denoted as "KPa"

Millimeter mercury is denoted as " mmHg"

Kilo pascal is measure of force per unit area while also define as newton per meter square.

It is manometric unit of pressure. It is the pressure generated by column of mercury one millimeter high.

Conversation of kilopascal to mmHg:

97.6 × 7.501 = 732.0601 mmHg

well for starters this atom is call chlorine

and this has a total mass of 35.075 or sum like that so C .35

hope this helped you in any kinda way

Answer:

Because of Hydrogen Bonding!

Answer:

NH3 has  stronger intermolecular forces compared to Cl2, due to NH3 having polar molecules, and hydrogen bonding.

Explanation:

There are three types of intermolecular forces:

Answer:

option B is correct :  The beam was positively charged.

Explanation:

In 19th century J.J Thomson conducted an experiment on cathode ray tube. These cathode ray tubes were sealed glass tubes inside which the pressure of the gas reduced by evacuating air. Then he applied a high voltage across two electrodes at end of the tube, that voltage caused a beam of particles to flow from the cathode to the anode.

Beam of the particles were originated at the cathode and detected on anode by a phosphorous beyond the anode. As at that time phosphorous sparks and emit light.

To test properties of particles he places two opposite charged electric plates around the cathode rays that is one negative and one positive plate.

Thomson observed that these rays deflected to positive electric plate so it indicated that these rays are composed of negatively charged particles as it was attracted by the positive charged electric plate. These particles later named as electrons.

So,

option B is correct :  The beam was positively charged.

Answer:

ENERGY SOURCE

Explanation:

JUST TOOK QUIZ

The other person is right,

the answer is

(B) energy source

Hope this helps <3

Answer:

Sexual reproduction can be described as the method of reproduction in which the offsprings produced will have half the chromosomes as compared to the parent cell. The other half of the chromosomes to make a complete set would arise from the other parent. In this way, the offspring produced will carry half of the chromosomes from the female parent and half from the male parent.

Crossing over and independent assortment are two phenomenons of meiosis due to which genetic diversity occurs and the offsprings born are not exactly similar to the parent cell.

Answer:  The four cells that are produced by meiosis has only one of each chromosome. One of these four cells from one parent combines with another from the other parent to produce the offspring. An offspring gets half its chromosomes from each parent. But the exact combination of chromosomes it gets from each parent is random. So, each offspring ends up with a unique set of genes different from its parents and other offspring.

Zn    +  Cu²⁺   →    Zn²⁺ +  Cu

Explanation:

The overall equation of this redox reaction is combination of the two half equations. The similar species on both sides are cancelled out leaving a net overall reaction:

           Zn → Zn²⁺  +  2e⁻      oxidation step

           Cu²⁺ + 2e⁻ → Cu        reduction step

Combining both equations:

Zn + Cu²⁺ + 2e⁻  → Zn²⁺  +  2e⁻  + Cu

since the common specie on both sides is  2e⁻, they cancel out to give an overall reaction:

                      Zn    +  Cu²⁺   →    Zn²⁺ +  Cu

learn more:

Redox reaction https://brainly.com/question/8727728

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Final answer:

The overall equation for the displacement reaction where zinc replaces copper is Zn(s) + Cu2+ (aq) → Zn2+ (aq) + Cu(s).

Explanation:

The question concerns the determination of the overall chemical reaction for a displacement reaction where zinc displaces copper from its solution. Starting from the half-reactions, the oxidation half-reaction is Zn(s) → Zn2+(aq) + 2e-, which indicates zinc is being oxidized by losing electrons. The reduction half-reaction for copper is Cu2+(aq) + 2e- → Cu(s), showing that copper ions are being reduced by gaining electrons. When we combine these two half-reactions, we must ensure that the electrons lost by zinc equal the electrons gained by copper to balance the reaction. Thus, the overall reaction is Zn(s) + Cu2+ (aq) → Zn2+ (aq) + Cu(s). This equation represents a single displacement reaction where zinc metal is transformed into its ionic form and copper ions are deposited as copper metal.

Answer:

Acids when dissolved in water produce hydrogen ions.

Explanation:

It is true that human impact on one system leads to changes in more of Earth’s systems.

Answer: Option A

Explanation:

Human impact had created large impacts on Earth’s systems. The pollution in air, deforestation, dumping of lakes lead to several changes in environment. Also emission of carbon, methane and other hazardous gases from several manufacturing unit effect the environment.

Along with this, increase in usage of non-renewable fuels and release of CFC's emitted from AC’s, fridge lead to elimination of ozone layer making the environment open to direct UV radiation. So yes, it is true that human impact on one system leads to changes in more of Earth’s systems.

Answer:

true

Explanation:

Answer:

The number in C-12 and C-14 represent their atomic masses.

Explanation:

The number in C-12 and C-14 represent their atomic masses.

These two are the isotopes of carbon.

Isotopes of an element have same atomic number and different atomic masses due to different number of neutrons present.

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.  All these three subatomic particles construct an atom.

All isotopes of carbon have same number of electrons and protons i.e, six

while C-14 has 8 neutrons and C-12 has six neutrons.

C-14 = 14-6 = 8

C-12 = 12-6 = 6

Thus sum of neutrons and protons is atomic mass that's why C-14 has 14 atomic mass (8+6=14) while C-12 has 12 atomic mass (6+6=12).

Directly determining the number of moles of KNO3 formed from KI is not feasible without a specific chemical reaction pathway, as KI typically does not directly convert into KNO3.

To determine the number of moles of KNO3 created when 0.03 moles of KI is completely consumed, we need a balanced chemical equation for the reaction involving KI and how it transforms into KNO3. Unfortunately, without a specific chemical reaction indicating how KNO3 is formed from KI, accurately calculating the moles of KNO3 produced directly from KI is challenging since KI typically does not transform directly into KNO3 through a simple chemical reaction. In typical laboratory or industrial settings, KNO3 is formed through different chemical pathways that do not directly involve KI as a reactant.

To determine the moles of KNO3 created from 0.03 moles of KI consumed,

Write and balance the chemical equation representing the reaction between KI and KNO3.

Use stoichiometry to calculate the moles of KNO3 formed from the moles of KI consumed.

Apply the coefficients of the balanced equation to convert moles of KI to moles of KNO3.

Therefore, without the explicit chemical reaction provided, we can conclude that the direct transformation from KI to KNO3, leading to a calculation of moles of KNO3 produced from a given amount of KI, is not standardly feasible. For accurate calculations, the exact chemical equation is necessary.