You have 900,000 atoms of a radioactive substance. After 4 half-lives have past, how many atoms remain?

you cannot have a fraction of an atom, so round the answer to the nearest whole number.

A soft drink contains 33g of sugar in 349g of H[tex]_2[/tex]O. 14.3%  is the concentration of sugar in the soft drink in mass percent.

One approach to indicate the concentration of any dissolved component in a solution is by mass percentage. Mass percentage is the ratio of the total weight of a compound in a solution to the overall mass of the solution, expressed in percentages.

In order to express the mass percent of a solution, the grammes of solute are divided by the grammes of solution, and the result is multiplied by 100. As long as you use a comparable number for both the component and solute mass.

Mass percent = (mass of solute/mass of solute+ mass of solvent)×100

                        = ( 33/ 33+ 349)×100

                         =14.3%

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All the 3 chemical species are drawn in the images below/

The E1 reaction mechanism instigates a variant of elimination reactions. It materializes in the vicinity of strong acids or bases and it initiates by eliminating a leaving group from the substrate, consequently creating an intermediate carbocation. Once completed, the mechanism eliminates a proton from a neighborly carbon, initiating the construction process of a double bond.

However, performing an E1 reaction in water may yield unexpected results due to water's nucleophilic nature, catalyzing sneaky attacks on the carbocation intermediates, leading to dissimilar products than initially intended. Furthermore, reactions performed with aqueous media cause other side-products thanks to hydrolysis mechanisms that emerge, making them undesirable.

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An example of a composition which fulfills the qualifications of being both a base and a weak electrolyte is ammonia (NH3).

A base is any constituent which voluntarily receives protons (H+) in an associated chemical reaction while an electrolyte denotes any material that can conduct electricity through liquids or in melted state.

Upon dissolution in water, it is apt to accept a proton from such and thus create the acidic ion known as ammonium (NH4+). Nonetheless, due to its scarce dissociation into hydroxide (OH-) and ammonium ions, it is deemed a weak electrolyte.

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Weathering changes the chemical and physical nature of an element that is why it is often difficult to identify a highly weathered mineral.

The breakdown and alteration of rocks and minerals at or near the Earth's surface as a result of exposure to various weathering agents, such as water, wind and temperature changes is known as weathering.

Minerals can undergo physical changes as a result of weathering, such as being broken up into smaller pieces or having their color and texture altered. Additionally, it may result in chemical alterations such as the removal or addition of specific chemical components.

This may lead to the creation of brand-new minerals or the modification of already existing minerals into new ones.  Highly weathered minerals might not still possess the same physical and chemical characteristics as their unweathered counterparts.

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The concept combined gas law is used here to determine the new volume of the balloon. This law relate one thermodynamic variable to another holding everything else constant. The new volume is 4.12 L.

The combination of Boyles law, Charles's law and Avogadro's law gives the combined gas law. This law states that the product of pressure volume and temperature of a system remains constant.

The equation is:

P₁V₁ / T₁ = P₂V₂ / T₂

V₂ = P₁V₁T₂ / P₂T₁

0.7455 × 3.1 × 279.9 / 0.528 × 296.8 = 4.12 L

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Answer:

cm=0.385 J

cm = (0.15 kg x 4.18 J/gCx (35C - 30C)) / (70 pieces x 0.1 kg/piece x (120C - 35C))

The answer is:

cm = 0.385 J/gc

Therefore, the specific heat of the metal is 0.385

Based on the properties of elements, elements can be arranged into groups in the periodic table as follows:

Group 1 to 3 - metals

Group 14 - non-metals, metalloids, and metals

Group 15 to 18 - non-metals

Groups are the names given to the periodic table's columns. In the table, individuals who belong to the same group make bonds of the same kind and have an equal number of electrons in their atoms' outermost shells.

Periods are the horizontal rows found in the periodic table.

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The chemical formulas are as follows:

Chemical formulas are shorthand notations used to represent the composition of a substance. In this case, the reactants used in Activity 2 are listed with their chemical formulas.

Barium nitrate is represented by the chemical formula Ba(NO₃)₂, which shows that it contains one barium ion (Ba²⁺) and two nitrate ions (NO₃⁻).

Sodium hydroxide is represented by the chemical formula NaOH, which shows that it contains one sodium ion (Na⁺) and one hydroxide ion (OH⁻).

Sodium hydrogen carbonate is represented by the chemical formula NaHCO₃, which shows that it contains one sodium ion (Na⁺), one hydrogen ion (H⁺), one carbonate ion (CO₃²⁻) and one hydrogen carbonate ion (HCO₃⁻).

Similarly, other reactants are represented by their respective chemical formulas.

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The value of Tan P as fraction simplest form is 15 / 29

The following data were obtained from the question:

Tan θ ratio is express as:

Tan θ = Opposite / Adjacent

Inputting the various parameters obtained from the question, we can obtain Tan P as shown below:

Tan P = Opposite / Adjacent

Tan P = 15 / 29

Thus, from the above calculation, we can conclude that the value of tan P in it's lowest fraction is 15 / 29

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a) HClO₄ is a strong acid, and in water, it will dissociate completely into H+ and ClO₄⁻. The concentration of H⁺ in this solution is therefore equal to the concentration of HClO₄:

[H⁺] = 6.0 x 10⁻³ M

Using the definition of pH, we have:

pH = -log[H⁺]

pH = -log(6.0 x 10⁻³)

pH = 2.22

b) Sr(OH)₂ will dissociate completely into Sr²⁺ and 2OH⁻. The concentration of OH⁻ in this solution is therefore twice the concentration of Sr(OH)₂:

[OH-] = 2 x 0.0009 M

[OH-] = 0.0018 M

Using the definition of pH, we have:

pOH = -log[OH-]

pOH = -log(0.0018)

pOH = 2.74

Since pH + pOH = 14, we have:

pH = 14 - pOH

pH = 14 - 2.74

pH = 11.26

c) Solution made by mixing 25.00 mL of 0.121 M HCl and 30.00 mL of 0.100 M KOH

HCl + KOH → H2O + KCl

The moles of HCl in 25.00 mL of 0.121 M HCl are:

moles HCl = concentration x volume

moles HCl = 0.121 mol/L x 0.025 L

moles HCl = 0.003025 mol

The concentration of HCl in the final solution is:

[HCl] = moles HCl / total volume of solution

[HCl] = 0.003025 mol / (25.00 mL + 30.00 mL)

[HCl] = 0.003025 mol / 0.055 L

[HCl] = 0.055 M

Similarly, the moles of KOH in 30.00 mL of 0.100 M KOH is:

moles KOH = concentration x volume

moles KOH = 0.100 mol/L x 0.030 L

moles KOH = 0.003 mol

The concentration of OH⁻ in the final solution is:

[OH⁻] = moles OH⁻ / total volume of solution

[OH⁻] = 0.006 mol / 0.055 L

[OH⁻] = 0.109 M

Using the definition of pH, we have:

pH = 14 - pOH

pH = 14 - (-log[OH⁻])

pH = 14 - (-log(0.109))

pH = 12.06

Thus, the pH of (a) is 2.22, (b) is 11.26, and (c) is 12.06.

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Answer:

a. The chemical equation for the reaction is:

2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂

b. To find the mass of required sulfuric acid, we need to use stoichiometry. We can start by finding the number of moles of aluminum used in the reaction:

Molar mass of Al = 27 g/mol

Number of moles of Al = 5.4 g / 27 g/mol = 0.2 mol

According to the balanced equation, 3 moles of H₂SO₄ are required to react with 2 moles of Al. Therefore, the number of moles of H₂SO₄ required is:

Number of moles of H₂SO₄ = 3/2 x 0.2 mol = 0.3 mol

Molar mass of H₂SO₄ = 2 x 1 g/mol + 32 g/mol + 4 x 16 g/mol = 98 g/mol

Mass of H₂SO₄ required = 0.3 mol x 98 g/mol = 29.4 g

Therefore, 29.4 g of sulfuric acid is required to react with 5.4 g of aluminum.

c. To find the volume of hydrogen gas obtained, we need to use the ideal gas law:

PV = nRT

where P is the pressure of the gas, V is its volume, n is the number of moles of the gas, R is the universal gas constant (0.0821 L atm/mol K), and T is the temperature in Kelvin.

We can start by finding the number of moles of hydrogen gas produced in the reaction. According to the balanced equation, 3 moles of H₂ are produced for every 2 moles of Al. Therefore, the number of moles of H₂ produced is:

Number of moles of H₂ = 3/2 x 0.2 mol = 0.3 mol

Assuming the reaction occurs at standard temperature and pressure (STP), which is 0°C (273 K) and 1 atm, we can use the molar volume of a gas at STP, which is 22.4 L/mol. Therefore:

V = nRT/P = 0.3 mol x 0.0821 L atm/mol K x 273 K / 1 atm = 6.58 L

Therefore, the volume of hydrogen gas produced at STP is 6.58 L.

Explanation:

Answer:

The name for CH3-CH2-C(O)-OCH3 is ethyl methanoate.

Explanation:

0.30M is the molarity of the given solution with 0.250 mol and 0.835 L volume of solution

The amount of moles of solute that exist in a specific number of litres of the solution, or moles per litre of a solution, is known as molar concentration or molarity. Solvent, and 'solution' to make it simpler to comprehend the principles that will follow. A homogenous combination with any number of solutes in it is referred to as a solution.

Molarity = number of moles/ volume of solution in liter

Molarity = 0.250/ 0.835

             = 0.30M

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0.50 L of a 1.5 m solution contains 71.4 grams of MgCl2.

The equation moles of solute = molarity x volume (in liters) can be used.

When converting to grams, we may use the molar mass of the MgCl2 to determine how many moles there are in the solution.

MgCl2 has a molar mass of roughly 95.21 g/mol.

The volume must first be changed from liters to milliliters:

0.50 L = 500 mL

Next, we may determine how many moles of MgCl2 are present in the solution:

moles of MgCl2 = molarity x volume (in liters)

moles of MgCl2 = 1.5 mol/L x 0.50 L

moles of MgCl2 = 0.75 moles

Finally, we can figure out how much MgCl2 is present in the solution:

mass of MgCl2 = moles of MgCl2 x molar mass

mass of MgCl2 = 0.75 moles x 95.21 g/mol

mass of MgCl2 = 71.4 grams

Therefore, 0.50 L of a 1.5 m solution contains 71.4 grams of MgCl2.

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Answer:430 mg/L = 0.43g/L 

Explanation:

To prepare a buffer solution of pH 9.00, we need to use the Henderson-Hasselbalch equation:

Where [A-]/[HA] is the ratio of the concentrations of the conjugate base and acid of the buffer, respectively. Since we are given the pH and the overall concentration of the buffer, we can solve for the ratio [A-]/[HA]:

Next, we can use the definition of the concentration of a solution to find the concentration of NH4Cl needed to make a 0.125 mol-L^-1 buffer solution:

0.125 mol-L^-1 = [NH4Cl] + [NaOH]

Since the NaOH solution is 1.00 mol-L^-1, we can assume that the contribution of NaOH to the total concentration of the buffer is negligible, and so:

Finally, we can use the molar mass of NH4Cl to find the mass of NH4Cl needed to prepare 1 L of the buffer solution:

So we need to use 6.63 g of NH4Cl and enough volume of 1.00 mol-L^-1 NaOH solution to make a total volume of 1 L. To find the volume of NaOH solution needed, we can use the definition of molarity:

Rearranging this equation, we get:

Since we are adding NaOH solution to NH4Cl to make a total volume of 1 L, the molality of NaOH solution is also 0.125 mol-L^-1. Therefore:

Substituting the values we know:

So we need to use 6.63 g of NH4Cl and 56 mL of 1.00 mol-L^-1 NaOH solution to prepare 1 L of a buffer solution of pH 9.00.

Answer:

To solve this problem, we can use the equation:

Q = m * c * ΔT

where Q is the heat transferred, m is the mass of the substance, c is its specific heat capacity, and ΔT is the change in temperature.

In this case, we know that the heat lost by the metal is equal to the heat gained by the water:

Q lost = Q gained

We can calculate the heat lost by the metal using the equation:

Q lost = m * c * ΔT

where m is the mass of the metal, c is the specific heat capacity of the metal (which we are trying to find), and ΔT is the change in temperature of the metal (100.5 C - 30.2 C = 70.3 C).

We can calculate the heat gained by the water using the equation:

Q gained = m * c * ΔT

where m is the mass of the water and ΔT is the change in temperature of the water (30.2 C - 20.0 C = 10.2 C).

Setting the two equations equal to each other, we get:

m * c * ΔT (metal) = m * c * ΔT (water)

Simplifying, we get:

c (metal) = (m * c * ΔT (water)) / (m * ΔT (metal))

Plugging in the values we know:

m (metal) = 32.8 g

ΔT (metal) = 70.3 C

m (water) = 138.2 g

ΔT (water) = 10.2 C

c (metal) = (138.2 g * 4.184 J/g·K * 10.2 C) / (32.8 g * 70.3 C)

c (metal) = 0.192 J/g·K

Therefore, the specific heat capacity of the metal is 0.192 J/g·K.

Answer:

If 2 half-lives have passed, it means that the radioactive substance has decayed twice, so the number of remaining atoms would be:

1st half-life: 400,000 / 2 = 200,000 atoms remaining

2nd half-life: 200,000 / 2 = 100,000 atoms remaining

Therefore, after 2 half-lives have passed, 100,000 atoms would remain, rounded to the nearest whole number

Explanation:

IF U NEED FURTHER HELP AND WANT TO BE FRIEND , SN AP = m_oonlight781

Answer:H = 5

Explanation: You would get this answer if you divide by 2 then multiple by 7

The reaction between calcium nitrate (Ca(NO₃)₂) and sodium oxalate (Na₂C₂O₄) can be represented by the following chemical equation:

Ca(NO₃)₂ + Na₂C₂O₄ → CaC₂O₄ + 2NaNO₃

This is a double displacement reaction, where the calcium ion (Ca²⁺) from calcium nitrate and the oxalate ion (C₂O₄²⁻) from sodium oxalate switch places to form calcium oxalate (CaC₂O₄) and sodium nitrate (NaNO₃). The balanced chemical equation shows that one mole of calcium nitrate reacts with one mole of sodium oxalate to form one mole of calcium oxalate and two moles of sodium nitrate.

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Answer:

The temperature of the iron block is 68.5°C.

Explanation:

The heat released during condensation of water is used to warm the iron block:

q = m_H2O * ΔH_vap = m_fe * c_fe * ΔT

where q is the heat released, m_H2O is the mass of water condensed, ΔH_vap is the enthalpy of vaporization for water, m_fe is the mass of iron, c_fe is the specific heat capacity of iron, and ΔT is the change in temperature of the iron block.

Rearranging the equation gives:

ΔT = (m_H2O * ΔH_vap) / (m_fe * c_fe)

Substituting the given values gives:

ΔT = (0.95 g * 44.0 kJ/mol) / (75.0 g * 0.449 J/(g°C))

ΔT = 46.5°C

Therefore, the final temperature of the iron block is:

T_f = T_i + ΔT = 22°C + 46.5°C = 68.5°C.

The final temperature of the iron block is 68.5°C.

Answer: I got you fam

Explanation:

The formula is Na2CO3 + ZnI2 → 2NaI + ZnCO3

Or -5.19

A thermochemical equation can be written by expressing the heat evolved or absorbed in terms of the enthalpy change ΔH. Here ΔH for the following reaction +88.2 kJ. The correct option is A.

A chemical equation which indicates the heat change occuring during the reaction is defined as the thermochemical equation. In thermochemical equations, physical states of the reactants and products should be specified.

Here the given reaction 4 AlCl₃ (s) + 3 O₂ (g) ⇒ 2 Al₂O₃ (s) + 6 Cl₂ (g) is reversed as 1 /3 Al₂O₃ (s) + Cl₂ (g) ⇒ 2/3 AlCl₃ (s) + 1/2 O₂ (g) and multiplied by 1/6.

So the new enthalpy is +88.16 ≈ 88.2 kJ

Thus the correct option is A.

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The potential across this cell membrane with only potassium channels open is -0.082 V, which means that the inside of the cell is negatively charged relative to the outside.

The potential across a cell membrane can be calculated using the Nernst equation:

E = (RT/zF) ln([ion]out/[ion]in)

 E = potential in volts, R= gas constant (8.314 J/mol*K), T= temperature in Kelvin, z = charge on the ion, F= Faraday constant (96,485 C/mol), and [ion]out and [ion]in are the concentrations of the ion outside and inside the cell, respectively.

K+ (intracellular) ⇌ K+ (extracellular)

The charge on potassium ions is +1, so z = 1.

The temperature is 37°C or 310 K.

The concentrations of potassium ions are [K+]in = 150 mM and [K+]out = 4.0 mM.

Substituting these values into the Nernst equation,

E = (RT/zF) ln([K+]out/[K+]in)

E = (8.314 J/mol.K × 310 K)/(1 × 96,485 C/mol) ln(4.0 mM/150 mM)

E = -0.082 V

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The concept molarity is an important method which is used to calculate the concentration of a solution. It is mainly employed to calculate the concentration of a binary solution. Here the volume of  barium hydroxide is 21.28 mL.

Molarity of a solution is defined as the number of moles of the solute present per litre of the solution. It is represented as 'M' and its unit is mol/L.

The equation connecting molarity and volume of two solution is given as:

M₁V₁ = M₂V₂

V₁  = M₂V₂ / M₁

0.1002 × 25.00 / 0.1177 = 21.28 mL

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The sound waves from the siren will reflect off the smooth surface of the wall. The light waves from the emergency vehicle will reflect off the smooth surface of the wall. Rougher sections of the wall surface will cause the light waves from the emergency vehicle to scatter.

When sound waves hit a smooth surface, they reflect off the surface in a predictable way called the law of reflection. So, the sound waves from the siren will reflect off the smooth surface of the wall.

Similarly, light waves also follow the law of reflection when they hit a smooth surface. Therefore, the light waves from the emergency vehicle will also reflect off the smooth surface of the wall.

However, when light waves encounter a rough surface, they scatter in all directions due to the irregularities on the surface. Therefore, rougher sections of the wall surface will cause the light waves from the emergency vehicle to scatter.

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Parts B and C of the marble's fall did the marble experience unbalanced forces. Option 4 is correct.

A force is a push or pull (interaction) which changes the momentum of an object, either stationary or in motion when unopposed. All objects experience different forces depending on their environment. When immersed in fluids, unbalanced forces of one upward moving force tends to cancel the gravity force moving downward on a sinking object causing deceleration to a constant sinking speed.

This upward moving force is called as Buoyant force. This is where at part A, the object will experiences a balanced force of gravity which accelerates due to the absence of an opposing force acting upwards on the object. At part B, the speed of the sinking object decreases due to an unbalanced force that cancels the acceleration by the buoyant force. Once the sinking object’s acceleration is cancelled, its sinking speed turns constant at part C.

Hence, 4. is the correct option.

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--The given question is incomplete, the complete question is

"A student used a video camera to record another student dropping a marble through water in a graduated cylinder. The students watched the video in slow motion and made the observations shown below. During which part or parts of the marble's fall did the marble experience unbalanced forces? (1) Part A only (2) Parts A and B only (3) Part C only (4) Parts B and C only."--