Which change of state is shown in the model?

condensation
deposition
boiling
freezing

Answer:

132 seconds ( 2 Minutes 12 seconds).

Explanation:

Half life is basically the time it takes for a compound to decay to half of it's original mass.

In this problem, the compound is As. The half life of As-81 is 33 seconds. This means it takes 33 seconds for 100 g of As-81 to decay to 50g. The question however id to find the time it takes for it to decay to 6.25g.

We find how many half life's it would take,

100 --> 50 (First half life)

50 --> 25  (Second half life)

25 --> 12.5 (Third half life)

12.5 --> 6.25 (Fourth half life)

This means the total time is 4 * 33 (Half life) = 132 seconds ( 2 Minutes 12 seconds).

Answer:

I, V, VI

Explanation:

During a state change, e.g solid state to liquid state, energy (absorbed or released) is used to break the bonds between the molecules. In the case of boiling,melting, and sublimation energy is absorbed to break the molecule bonds.

Answer:

C15H8Cl8O2

Explanation:

C15H8Cl8O2

Final answer:

The ratio of densities (ρ1/ρ2) of two non-mixing liquids in a U-tube that are in equilibrium can be found by equating the hydrostatic pressures of the liquids at the same height, resulting in the ratio ρ1/ρ2 = h2/h1.

Explanation:

The student is inquiring about the ratio of densities (ρ1/ρ2) of two non-mixing liquids in a U-tube that are in equilibrium. To find this ratio, we use the fact that the pressure at the same height must be the same in both arms of the U-tube if they are in the same liquid. Considering the point at the interface on the side with Liquid 1 and a point at the same level in the arm with Liquid 2, we can write the pressure due to Liquid 1 as P1 plus the atmospheric pressure. Likewise, the pressure due to Liquid 2 is P2 plus the atmospheric pressure. Because these pressures must be equal, we can set up the equation P1 + atmospheric pressure = P2 + atmospheric pressure.

Now, if we consider the column of Liquid 1 to have a height of h1 and the column of Liquid 2 to have a height of h2, we can equate the hydrostatic pressures using ρ1gh1 for Liquid 1 and ρ2gh2 for Liquid 2. The resulting equation is ρ1gh1 = ρ2gh2, where g is the acceleration due to gravity. Canceling out the common factor of g, we have ρ1h1 = ρ2h2. Dividing both sides by h2 and ρ1, we get the ratio of densities as ρ1/ρ2 = h2/h1.

Final answer:

approximately 8.51 kg of the ore must be processed

Explanation:

To calculate the minimum mass of ore required to obtain 1.00 kg of phosphorus from an ore containing 58.9% calcium phosphate (Ca3(PO4)2), we follow these steps:

First, calculate the molar mass of calcium phosphate, Ca3(PO4)2. The molar mass is (3×40.08 for Ca) + (2×30.97 for P) + (8×16 for O) = 310.18 g/mol.

Next, understand that calcium phosphate contains two moles of phosphorus per formula unit, which means every mole of calcium phosphate yields 2 moles of phosphorus.

To get 1.00 kg (or 1000 g) of phosphorus, we need 1000 g / 30.97 g/mol = 32.29 moles of phosphorus.

Since 1 mole of Ca3(PO4)2 yields 2 moles of phosphorus, we need 32.29 / 2 = 16.145 moles of calcium phosphate.

To find the mass of calcium phosphate required, multiply the moles by its molar mass: 16.145 mol × 310.18 g/mol = 5006.05 g.

Given that the ore is 58.9% calcium phosphate, the total mass of the ore needed is calculated as 5006.05 g / 0.589 = 8505.18 g, or approximately 8.51 kg.

The transition metals are located in the d block of the periodic table, which is found between Groups 3-12 and includes elements with partially filled d orbitals.

The transition metals are located in the d block of the periodic table. These elements, which have partially filled d orbitals, are found between Groups 3-12. The d block is characterized as the middle 10 columns of the periodic table. While the s block consists of the first two columns on the left side of the periodic table, and the p block refers to the right-most six columns, the d block is distinct in that it includes the transition metals known for their unique chemical and physical properties such as conductivity and malleability. The f block, often considered separate, is comprised of the lanthanides and actinides and does not include the transition metals.

Answer:

D

Explanation:

I took the test

Determine which chemicals to use to fight different types of fires.

Hello,

The correct answer is B) Molecules

Hope this helps!!!! :)

(Took the Science test)

**Please don't forget to mark brainliest answer!

Molecules come just after atoms in the organization chart of living things. Therefore, option B is correct.

A molecule can be defined as a combination or arrangement of two or more atoms that create the smallest unit into which the structure and chemical properties can be classified and preserved by a pure substance.

A molecule can be homonuclear if it exhibits atoms of a single chemical element such as hydrogen molecule (H₂) or it can be heteronuclear such as water (H₂O).

A molecule exhibits an arrangement of atoms held by the forces of valence. Two atoms of the same element that are chemically combined comprise diatomic molecules.

Heteronuclear diatomic molecules have two combined atoms of different elements such as hydrochloric acid (HCl), Carbon monoxide (CO), etc.

The molecules in living organisms are biomolecules such as carbohydrates, lipids, nucleic acids, proteins,

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To prepare 108.0 mL of a 0.45 M H2SO4 solution, you would need to measure 9.72 mL of the 5.0 M H2SO4 stock solution.

To solve this problem, we can use the concept of dilution. The formula for dilution is C1V1 = C2V2, where C1 and V1 are the concentration and volume of the stock solution, and C2 and V2 are the concentration and volume of the diluted solution.

In this case, the given concentration of the stock solution is 5.0 M and the volume of the stock solution needed is unknown. The desired concentration of the diluted solution is 0.45 M and the volume of the diluted solution is 108.0 mL. Plugging in these values into the dilution formula will give us the volume of the stock solution needed.

Let's solve for V1:

(5.0 M)(V1) = (0.45 M)(108.0 mL)

V1 = (0.45 M)(108.0 mL)/(5.0 M)

V1 = 9.72 mL

Therefore, you would need to measure 9.72 mL of the 5.0 M H2SO4 stock solution to prepare 108.0 mL of 0.45 M H2SO4.

The rate of appearance of Br2 in the gas phase reaction 2HBr(g) → H2(g) + Br2(g) when the rate of disappearance of HBr is 0.190 M/s at 150 °C is 0.095 M/s.

To determine the rate of appearance of Br2 in the reaction 2HBr(g) → H2(g) + Br2(g), we use the stoichiometry of the reaction. Given that the rate of disappearance of HBr is 0.190 M/s, and considering that 2 moles of HBr produce 1 mole of Br2, the rate of appearance of Br2 would be half of the rate of HBr's disappearance.

Therefore, the rate of appearance of Br2 is:

So, the rate of appearance of Br2 is 0.095 M/s.

During the Glacial erosion by abrasion the glaciers are loaded with other rock fragments as a tool for erosion of the bedrock. These rock fragments are dragged on the bedrock during the forward movement of the glacier and causes the rocks that comes in contact to abrade and the process is known as abrasion.

These abraded mass can also get trapped in the glacier as sub glacial, intra glacial and even super glacial deposit , causing the glacier to increase in mass and hence may flow easily where the glacier flow because of gravity. Abrasion also causes melting of snow because of the frictional heat produced during interaction of rock fragments and country rock.

option D

Answer:

The answer is D

Explanation:

plucks up rocks and incorporates them into its ice.

Answer : The correct options are, (a), (c), (d) and (f).

Explanation :

There are some safety rules for science lab when we are performing the experiments :

There are some safety rules for science lab in case of a laboratory accident:

Hence, the correct options are, (a), (c), (d) and (f).

A pure covalent bond occurs when two identical atoms share electrons equally, resulting in a nonpolar covalent bond.

A pure covalent bond occurs when two covalently bonded atoms are identical. In this type of bond, the electrons are shared equally between the two atoms, resulting in a nonpolar covalent bond. Nonpolar covalent bonds form between two atoms of the same element or between different elements that share electrons equally, such as molecular oxygen (O2).

Pure covalent bonds typically form in situations where the participating atoms are of the same element, such as in the case of molecular oxygen (O2), where two oxygen atoms share electrons equally. Understanding pure covalent bonds is essential in comprehending the nature of chemical bonding and the characteristics of various compounds.

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autotrophs are organisms that can synthesise organic compounds (e.g.: carbohydrates) from inorganic C compounds (e.g.: CO2)

Phototrophs are those use photons also known as light energy, chemotrophs are those who utilize chemical energy as their source of energy. chemotrophs can either use inorganic or organic molecules as source of energy. from the options given there are 2 answers with CO2, the correct combination is CO2 with inorganic compounds

Therefore chemoautotrophs use inorganic compounds as an energy source and CO2 as a carbon source

The pH in chemistry has been defined as the "power of hydrogen" that specifies and estimates the acidity and basicity. The pH of the solution with a hydroxyl concentration of 10⁻¹⁰ is 4. Thus, option c is correct.

pH has been defined as the  "potential of hydrogen" that is used to define the specificity of the acid and alkaline behavior of the solution. It has been the measure of the hydrogen or the hydroxide ions concentration dissociated into the solution.

pH is calculated as:

pH = −log ([H⁺])

Given,

Hydroxide ion concentration = 10⁻¹⁰

The relation between pH and pOH is given as:

pOH = - log [OH⁻]

pH = 14 - pOH

pOH is calculated as:

pOH = - log [OH⁻]

pOH = - log [10⁻¹⁰]

pOH = 10

Substituting values in the formula for pH as:

pH = 14 - pOH

pH = 14 -10

= 4

Therefore, option c. the pH is 4.

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Answer:

if its on edge this is what it provides!

- Surfactants are used to help improve gas exchange in the lungs of premature infants.

- Surfactants are used to prevent salad dressings from separating.

- Pulmonary surfactants reduce the surface tension of the gas exchange surfaces in the lungs, allowing gases to diffuse more easily.

- Surfactants help the water molecules and oil molecules in salad dressings interact and mix.

Make sure to change up the answer a bit!

The balanced chemical equation for the decomposition of hydrogen peroxide into water and oxygen is 2 H2O2 (aq) → 2 H2O (l) + O2 (g).

The student has asked for the balanced chemical equation for the decomposition of hydrogen peroxide (H2O2) into water (H2O) and oxygen gas (O2). The reaction can be represented as follows:

2 H2O2 (aq) → 2 H2O (l) + O2 (g)

Here, the hydrogen peroxide molecules are breaking down into water molecules and oxygen gas. The equation is balanced with four hydrogens and four oxygens on both sides; therefore, adhering to the law of conservation of matter.

Final answer:

Option C) CO2

Explanation:

All the substances listed are nonpolar, meaning they mainly experience London dispersion forces, which are the weakest intermolecular forces. However, they can vary in strength based on molecular mass and shape. Among the options, CO2 has more polarizable electrons due to its larger size and linear shape compared to Xe, H2, and CH4, thus exhibiting slightly stronger London dispersion forces. However, it's crucial to note that this comparison is subtle because the strengths of dispersion forces can be closely contested among molecules of similar sizes and molar masses. Therefore, CO2 would exhibit the strongest intermolecular forces among the given choices, but the difference might not be highly significant compared to the others, especially CH4.

Answer:

The correct answer is "the double covalent bond theory".

Explanation:

Each oxygen atom has 6 valence electrons in the outermost layer. To have greater stability you need to gain two electrons per atom. Therefore two oxygen atoms form a double bond by sharing two electrons each, completing the Lewis octet to acquire greater stability.

Have a nice day!

Final answer:

The claim that a balloon's internal pressure increases due to Charles's Law on a hot day is false; Charles's Law relates gas volume to temperature at constant pressure, meaning the balloon's volume would increase, not pressure.

Explanation:

The statement that balloon molecules inside a balloon will increase in pressure on a hot summer day according to Charles's Law is false. Charles's Law actually states that the volume of a given amount of gas is directly proportional to its temperature on the Kelvin scale when the pressure is held constant. When the temperature inside the car increases, the gas molecules inside the balloon move faster and if the balloon is elastic and can expand, the volume of the gas will increase while the pressure inside the balloon will not necessarily increase if it is free to expand.

The correct answer is option C, that is, the electric potential (volts) divided by the current (amperes) equals the resistance (ohms).  

According to the Ohm's law, the current via a conductor between the two points is directly equivalent to the voltage through the two points. With the introduction of resistance, that is, the constant of proportionality, the mathematical equation, which describes the association is:  

I = V/R

Here, I is the current via the conductor in the units of amperes, R is the resistance of the conductor in the units of ohms, and V is the voltage determined across the conductor in the units of volts.  

Answer:

The correct answer is option D. The less a star appears to move, the farther it is from earth.

Explanation:

Hi!

Let's solve this!

The stars, like the Earth move. We see them still as they are far away, the distance is very large. The stars we see in motion are the ones that are very close.

Then, the further a star is, the quieter we will see it.

After the analysis, we conclude that the correct answer is option D. The less a star appears to move, the farther it is from earth.

Final answer:

The molar mass of a gas can be calculated using the ideal gas law equation at STP. The molar mass of the gas with a density of 1.97 g/L at STP is 44.1 g/mol.

Explanation:

The molar mass of a gas can be calculated using the ideal gas law equation, PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature. At STP (Standard Temperature and Pressure), the pressure is 1 atm and the temperature is 273 K. We can rearrange the equation to solve for the molar mass, M:

M = (PV) / (nRT)

Given that the density of the gas is 1.97 g/L at STP, we can calculate its molar mass by converting the density to grams per mole:

Density = Molar mass / Molar volume

Molar volume at STP = 22.4 L/mol

Thus, Molar mass = Density * Molar volume

Molar mass = 1.97 g/L * 22.4 L/mol = 44.1 g/mol

The molar mass of the gas is 44.1 g/mol.

Chemical reactions involve transforming reactants into products, altering their molecular structure and leading to different chemical and physical properties. These transformations are represented by chemical equations, which ensure the conservation of atoms in the reactants and products.

Chemical Changes and Chemical Reactions

When discussing the types of change and the chemical properties of the product and reactants, we're looking at chemical reactions. A chemical change transforms one molecular substance into another, altering its molecular structure and creating new substances with different properties. For example, when gasoline burns, it reacts with oxygen to produce heat, light, carbon dioxide, and water vapor. This transformation is represented by a chemical equation, which shows the reactants on one side and the products on the other, linked by an arrow indicating the direction of change.

Reactants are the starting materials in a chemical reaction, and products are the substances formed as a result of the chemical reaction. During this process, chemical bonds in the reactants are broken, and new bonds are formed in the products, leading to a different arrangement of atoms and thus new chemical and physical properties of the substances involved.