Which of the following statements is true?
A. Dalton believed atoms were made mostly of empty space
B. Plasmas have a net negative charge
C. The number of protons in an element is always equal to the number of neutrons
D. Solids have a fixed mass, volume, and shape

Final answer:

When an acid dissolves in water, it dissociates into hydrogen ions (H+) and anions, with strong acids fully dissociating and weak acids only partially. The H+ ions often form hydronium ions (H3O+) in the solution.

Explanation:

When an acid dissolves in water, you would expect to find hydrogen ions, denoted as H+, and anions specific to the acid. For instance, if hydrochloric acid (HCl) is dissolved, it dissociates into H+ and chloride ions (Cl-). This process is a characteristic feature of acids in an aqueous solution. A strong acid, such as sulfuric acid (H2SO4), will completely dissociate into 2 H+ ions and a sulfate ion (SO42-). These hydrogen ions often associate with water molecules to form hydronium ions (H3O+), making the solution acidic.

Svante Arrhenius defined an acid as a substance that produces H+ ions when dissolved in water, and this concept is key in understanding the behavior of acids in aqueous solutions. Weak acids, in contrast, partially dissociate, producing fewer hydrogen ions and their corresponding anions compared to strong acids.

by increasing the surface area of a solid reactant, this can cause the rate of a chemical reaction to rise. If you cut it into pieces or make it into powder when the surface area is increased more particles will be exposed

Answer:

Glass, floor tile, wood, and sandpaper

Explanation:

Answer:

A

Explanation:

Pure substances are substances made of only one compound, and mixtures, substances made of two or more compounds. To separate the compounds of a mixture, it can be used chemical or physical separation. For example, to separate sand and water it may be used as a filter, which is a physical separation. But if there are small particles in the water, maybe it would be necessary coagulation with some chemical element before a filtration, which would be a chemical separation.

To separate the elements of a pure substance, only chemical separations can be used: would be necessary a chemical reaction to form H2 and O2 from H20, for example. So, letter A is correct.

Letter B is incorrect because can be differents atoms in the mixture, depends on its components.

Letter C is incorrect because all molecules, compounds, and substances have chemical bonds, it's the force that let the elements be together.

Letter D is incorrect because, as explained, pure substances only can be separated in their elements by a chemical reaction.

Fruit batteries use the natural acids in fruits to generate electricity and are eco-friendly on a small scale. They have educational value but are not practical for large-scale energy needs. They're more environmentally friendly than traditional batteries with harmful chemicals.

Fruit batteries operate by using the natural acids present in fruit, such as citric acid in lemons, to conduct electricity. This is a result of a chemical reaction between two different metals inserted into the fruit (usually copper and zinc), which act as electrodes.

Fruit batteries are an innovative way to generate a small amount of electricity without the use of fossil fuels or other non-renewable resources, making them environmentally friendly on a small scale. However, for practical and large-scale energy needs, fruit batteries are not viable due to their low power output and the impracticality of using large amounts of fruit for significant electricity generation.

Despite this limitation, the concept of fruit batteries can be useful in educational settings where demonstrating the basics of electrochemistry is desired. They are also more eco-friendly than many traditional batteries, which often contain harmful chemicals and heavy metals that can pollute the environment when not disposed of properly.

The formula for rubidium nitride is Rb₃N. Rubidium nitride is an inorganic compound composed of rubidium (Rb) and nitrogen (N) atoms.

It is an ionic compound formed by the reaction between rubidium metal and nitrogen gas. It is a solid compound that exists as a crystal lattice structure. Each rubidium ion (Rb⁺) is surrounded by nitride ions (N₃⁻) in a regular arrangement, forming a three-dimensional network of positive and negative ions held together by electrostatic forces.

Rubidium nitride is highly reactive and sensitive to moisture and air.

Learn more about rubidium, here:

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Final answer:

Greenhouse gases trap heat in Earth's atmosphere, contributing to the greenhouse effect which warms the planet. Gases like carbon dioxide and methane are key players in this process, as they reflect thermal energy back to Earth, increasing its average temperature and affecting the climate.

Explanation:

Greenhouse gases significantly impact climate by affecting the heat flow into and out of Earth's atmosphere. When the sun's energy reaches Earth, greenhouse gases such as carbon dioxide, methane, water vapor, nitrous oxide, and ozone, trap heat in the atmosphere. About half of the sun's radiation penetrates these gases and warms the Earth, which then re-radiates thermal energy back into the atmosphere. Greenhouse gases act like a reflective barrier, bouncing much of this thermal energy back to the Earth's surface, thereby warming both the surface and the atmosphere.

This warming is known as the greenhouse effect, and greenhouse gases are critical because they absorb and emit radiation. The more greenhouse gases present, the more heat is trapped, leading to an increase in Earth's average temperature. This process contributes to global climate change, as the accumulation of greenhouse gases from human activities enhances this natural warming effect.

Answer: Option (b) is the correct answer.

Explanation:

It is known that density is the amount of mass divided by volume.

When water is present in solid state that is, in the form of ice then its molecules arrange themselves in a rigid tetrahedral structure.

Due to this there will cage like spaces between the molecules of ice during the bonding. As a result, they occupy more volume and it is known that density is inversely proportional to volume.

Hence, ice has low density as compared to liquid state of water.

When water is present in liquid state, then its molecules are closer to each other and they are able to slide past each other. Hence, space between them is less therefore, lesser will be its volume.

As a result, liquid state of water will have more density.

Thus, we can conclude that water is different from other substances  because it is less dense as a solid than liquid.

The first four, then the first. Hope this helps!

When farmers use chemicals to kill some weed or bugs, those chemicals also were absorbed by the plant and the soil.

That absorption can affect fertility because the chemical can change some chemical and physical traits from the soil and plant.

In worse cases, it can cause erosion, this means,  that the soil is "dead" and nothing will grow.

To produce the chemical reaction that yields water, in addition to hydrogen and oxygen, energy is also required. This can come in the form of heat. A common type of chemical reaction resulting in water is dehydration synthesis.

Besides hydrogen and oxygen, energy is required to produce the chemical reaction that yields water. For example, this energy can come in the form of heat, as shown by the enthalpy change of the reaction 2H₊ + O → H₂O, which indicates that 286 kJ of heat are released when hydrogen and oxygen gases react to form water.

A known type of reaction involving the production of water is the dehydration synthesis. In this case, one reactant gives up a hydrogen atom and another gives up a hydroxyl group (OH), causing a molecule of water as a byproduct.

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The correct answer is:

flatworm

Explanation:

Ganglia is a bunch of nerves or a group of nerves outside the central nervous system.A flatworm has a very simple nervous system with two nerve cords moving down either side. It has two simple brains assembled ganglia, which are simple packages of nerves.

Answer:

sunlight oxygen and stones

Answer: The correct answer is volume.

Explanation:

Mass is defined as the amount of matter that is contained in an object. It is measured in kilograms.

Volume is defined as the amount of space that an object occupied. It is measured in [tex]m^3[/tex]

Density is defined as the ratio of an object's mass and volume. It is measured in [tex]kg/m^3[/tex]

[tex]\text{Density of a substance}=\frac{\text{Mass of a substance}}{\text{Volume of a substance}}[/tex]

Gravity is defined as the force that attracts the body to the center of the earth.  It is measured in Newtons.

Hence, the correct answer is Volume.

Answer:

Explanation:

This is because  the valence electrons are not "fixed in the outer shell" but the metallic bonded electrons flow freely around positive ions

If the heat given off in the dissolving reaction is less than the heat required to break apart the solid, the net dissolving reaction is endothermic. The addition of more heat facilitates the dissolving reaction by providing energy to break bonds in the solid. This is the most common situation where an increase in temperature produces an increase in solubility for solids.

The use of first-aid instant cold packs is an application of this solubility principle. A salt such as ammonium nitrate is dissolved in water after a sharp blow breaks the containers for each. The dissolving reaction is endothermic - requires heat. Therefore the heat is drawn from the surroundings, the pack feels cold.

The effect of temperature on solubility can be explained on the basis of Le Chatelier's Principle. Le Chatelier's Principle states that if a stress (for example, heat, pressure, concentration of one reactant) is applied to an equilibrium, the system will adjust, if possible, to minimize the effect of the stress.  This principle is of value in predicting how much a system will respond to a change in external conditions.  Consider the case where the solubility process is endothermic (heat added). An increase in temperature puts a stress on the equilibrium condition and causes it to shift to the right.  The stress is relieved because the dissolving process consumes some of the heat. Therefore,  the  solubility  (concentration)  increases  with  an  increase  in  temperature.    If  the process is exothermic (heat given off). A temperature rise will decrease the solubility by shifting the equilibrium to the left.

Answer:

Organism: Chicken

Explanation:

Let's suppose we have a chicken.

Chicken is a multicellular organism, with several parts such as wings, legs among many others.

The first part of cell theory: All organisms are made of one or more cells. Chicken is composed of several cells, cells are a couple in organs, such as hearth, legs and other. Each organ is composed of a specialized type of cell.

The second part of cell theory: The cell is the basic unit of organisms.The cell is the minimum expression of living organisms. Cells can eat, drink, digest and breath. Due to it, cells are the basic unit of organisms. Each cell inside the chicken can achieve own functions by itself.

Third. All cells come from existing cells.If we analyze the chicken origin, we can notice that chicken life began as an egg, a single giant cell. With time going, the single cell of the chicken was reproducing until it reaches the organism and many cells. In this sense, all chicken cells come from a single existing cell of the egg. 

The position of the moon at noon in San Diego depends on its phase and can be anywhere in the sky during the day.

When it is noon in San Diego, the position of the moon depends on its phase. The moon can be anywhere in the sky during the day as it orbits around the Earth. So, the moon could be above the horizon, below the horizon, or even directly overhead, depending on its position in its orbit at that specific time. It's important to note that the moon can be visible during the day as well, especially if it's a crescent or a half moon.

Answer:

It is C. Volcanoes

Explanation:

Final answer:

The half-life of the radioactive element is 4000 years.

Explanation:

In radioactive decay, the half-life is the time it takes for the activity (or radioactivity) of a substance to decrease by half.

Let's consider an example: If 50% of a radioactive element remains after 4000 years, we can determine its half-life by finding the time it takes for the original quantity to reduce by half (50%). In this case, it took 4000 years for the element to reduce from 100% to 50%. Therefore, the half-life of the element is 4000 years.

The balanced equation for Aluminum reacts with lead II nitrate is: 2 Al + 3 Pb(NO3)2 → 2 Al(NO3)3 + 3 Pb

The balanced equation for the chemical reaction where Aluminum (Al) reacts with lead (II) nitrate (Pb(NO3)2) is :

2 Al + 3 Pb(NO3)2 → 2 Al(NO3)3 + 3 Pb

This reaction is a single displacement reaction. In this type of reaction, one element displaces another in a compound. In this case, Aluminum (Al) displaces lead (Pb) in the lead II nitrate compound.

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