20 points to whoever can answer these 3 questions correctly

Half-life is a probabilistic measurement; it does not imply that, when the half-allotted life's time has passed, exactly half of the substance will have decomposed.

However, it is an approximation that becomes highly accurate when there are enough nuclei.

At=A0(1/2)t/t1/2

Where

A(0) is the initial amount of the substance and t1/2 is the half-life of the substance.

A(0)= 1000 atoms

t=4.79x10⁹ years

t/t1/2=1

=1000x1/2

=500 atoms

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Specific heat is the amount, like the other brainly answer said, of heat per unit mass required.

Answer: The velocity of the first ball is 0.875 m/s if the second ball travels at 1.5 m/s after collision.

Explanation:

Given: \(m_{1}\) = 0.2 kg,      \(m_{2}\) = 0.15 kg

\(v_{1}\) = 2 m/s,    \(v_{2}\) = 0 m/s,      \(v'_{1}\) = ?,          \(v'_{2}\) = 1.5 m/s

Formula used is as follows.

\(m_{1}v_{1} + m_{2}v_{2} = m_{1}v'_{1} + m_{2}v'_{2}\)

where,

v = velocity before collision

v' = velocity after collision

Substitute the values into above formula as follows.

\(m_{1}v_{1} + m_{2}v_{2} = m_{1}v'_{1} + m_{2}v'_{2}\\0.2 kg \times 2 m/s + 0.15 kg \times 0 m/s = 0.2 kg \times v'_{1} + 0.15 kg \times 1.5 m/s\\0.4 kg m/s + 0 = 0.2v'_{1} + 0.225 kg m/s\\0.2v'_{1} kg = 0.175 kg m/s\\v'_{1} = \frac{0.175 kg m/s}{0.2 kg}\\= 0.875 m/s\)

Thus, we can conclude that the velocity of the first ball is 0.875 m/s if the second ball travels at 1.5 m/s after collision.

The gauge pressure at a depth below the surface of a water is 3.0 atm.

If a person cannot tell the difference between gauge pressure and absolute pressure, they might believe the height (depth) is 30 metres.

Given the information below:

A = 3 atm is the atmospheric pressure.

A = 20 metres for height vs depth.

• 30 metres of depth at height.

Scientific evidence

• Gravitational acceleration is 9.8 m/s2.

• Water has a density of 1000 kg/m3.

In order to determine the gauge pressure at a depth below the water's surface:

Gauge pressure can be calculated mathematically using this formula:

P = pgh

where: G is the gravitational acceleration.

Water is at a height (depth) of h.

The formula reads as follows when the supplied parameters are substituted: P = 1000 × 9.8 x 30 Gauge pressure = 294000 Pa

The figure in Pascals would then be converted to atmosphere.

Conversion:

1 atm equals 101325 Pa, and X atm is 294000 Pa.

X = 294000 / 101325 X = 2.90 X = 3.0 atm is the result of cross-multiplying.

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Answer:

b

Explanation:

i am smart

All elements are mostly pure substances. A few of them include gold, copper, oxygen, chlorine, diamond, etc. Compounds such as water, salt or crystals, baking soda amongst others are also grouped as pure substances.

Explanation:

\(\Large\textbf{C) Mixtures}\)

6.61 grams of NaOBr must be dissolved in 488 mL of 0.260 M HOBr to produce a buffer solution with pH 8.30.

Bromine reacts with sodium hydroxide to produce sodium hypobromite (NaOBr), which changes the primary amide into an isocyanate intermediate.

To calculate the mass of NaOBr needed to produce a buffer solution with a pH of 8.30, we need to use the Henderson-Hasselbalch equation:

pH = pKa + log([A-]/[HA])

where pKa is the acid dissociation constant of HOBr, [A-] is the concentration of the conjugate base (OBr-) and [HA] is the concentration of the acid (HOBr).

We can rearrange this equation to solve for [A-]/[HA]:

[A-]/[HA] = 10^(pH - pKa)

We know the pH of the buffer solution (pH = 8.30) and the pKa of HOBr is 8.65. Therefore:

[A-]/[HA] = 10^(8.30 - 8.65) = 0.425

Since the initial concentration of HOBr is 0.260 M, we can set up the following equation to find the concentration of OBr- needed:

0.425 = [OBr-]/0.260

[OBr-] = 0.1105 M

Now, we can use the volume of the solution and the concentration of OBr- to calculate the moles of NaOBr needed:

moles of NaOBr = moles of OBr- = [OBr-] x volume

moles of NaOBr = 0.1105 M x 0.488 L = 0.0538 moles

Finally, we can use the molar mass of NaOBr to convert moles to grams:

mass of NaOBr = moles of NaOBr x molar mass of NaOBr

mass of NaOBr = 0.0538 moles x 122.89 g/mol = 6.61 g

Therefore, 6.61 grams of NaOBr must be dissolved in 488 mL of 0.260 M HOBr to produce a buffer solution with pH 8.30.

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The equation 2H2O ⇌ H3O+ + OH- represents the self-ionization of water, where water molecules can react with each other to form hydronium ions (H3O+) and hydroxide ions (OH-).

If H3O+ is added:

Adding hydronium ions (H3O+) will shift the equilibrium to the left, favoring the reverse reaction. This means more water molecules will combine to form H2O, reducing the concentration of H3O+ ions.

If H3O+ is taken away:

Removing hydronium ions (H3O+) will shift the equilibrium to the right, favoring the forward reaction. This means more water molecules will ionize to form H3O+ ions to compensate for the loss.

If OH- is added:

Adding hydroxide ions (OH-) will shift the equilibrium to the left, favoring the reverse reaction. This means more water molecules will combine to form H2O, reducing the concentration of OH- ions.

If OH- is removed:

Removing hydroxide ions (OH-) will shift the equilibrium to the right, favoring the forward reaction. This means more water molecules will ionize to form OH- ions to compensate for the loss.

In summary, adding or removing H3O+ or OH- ions will cause the equilibrium to shift in order to maintain the balance of concentrations and satisfy the equilibrium expression.

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Explanation:

For those who like to step beyond the challenge, the mass of the materials could be measured to check the methodology. Prior to separating the mixture, measure the mass of the total mixture. After separating and drying all the materials, measure the mass of each material. Add the three masses together. The total should equal the initial mass if all materials were recaptured during the separation process.

Iron particles will be drawn towards a magnet when one is used. In this manner, aluminum powder and iron powder can be separated. Due to the fact that iron is magnetic but the other three are not.

Magnets are used in magnetic separation, a waste management technique, to remove metal from the trash. As the materials are gathered together and segregated before processing, this is most frequently seen in single and mixed streams of recycling.

This method can be used to eliminate unwanted metals from products. All materials are kept pure by it. Recycling facilities frequently use magnetic separation to isolate metals, purify ores, and separate components from recycling.

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We have the balanced equation for the reaction.

To determine which is the limiting reactant we must know the moles of both reactants. We have the moles of Al equal to 3.8 mol. We calculate the moles of HCl with the data that they give us of molarity and volume in the following way:

Now, the ratio according to the HCl to Al reaction equation is 6/2=3/1.

The HCl to Al ratio that we have according to the available moles is: 10/3.8=2.63. This ratio is lower than the theoretical one, that is, there are not enough moles of HCl if all the moles of Al are to be reacted. Therefore, HCl is the limiting reactant.

The calculations are made according to the moles of HCl available. Now the ratio H2 to HCl is 3/6=1/2. So the moles of H2 will be:

The theoretical yield is 5.0molH2.

The answer is: 5.0 moles of H2, HCl being the LR. 4th option

Answer:

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A cell containing 97% h₂o is placed into a 90% h₂o  solution. the solution is to the cell and there the size of the cell will shrink .

             Solute + Solvent = Solution

The cell will cremate because the water in the solution will gets released and there the state of equilibrium exists and that can be determined as Hypertonic solution.

A liquid that has a higher concentration of dissolved particles than regular cells and blood do, like salt and other electrolytes. For instance, wounds are soaked in hypertonic liquids.

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Answer:

carbon dioxide and oxygen

Answer:

A is the load.

Explanation:

A is the load.

B is the resistance arm.

C is the fulcrum.

D is the effort arm.

E is the effort.

I hope this helps!

According  to stoichiometry and concept of Avogadro's number there are 3.61×10²⁴ particles for 4 moles of KClO₃.

It is the determination of proportions of elements or compounds in a chemical reaction. The related relations are based on law of conservation of mass and law of combining weights and volumes.

Stoichiometry is used in quantitative analysis for measuring concentrations of substances present in the sample.As 2 moles of potassium chlorate gives 3 moles of oxygen , thus 4 moles of potassium chlorate will give 4×3/2=6 moles , 6 moles have 6×6.023×10²³=3.61×10²⁴ particles.

Thus,  there are 3.61×10²⁴ particles for 4 moles of KClO₃.

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Answer:

Volume = 190.8

Approximately 12.45 grams of solid silver chromate will precipitate when 150 mL of 0.500 M silver nitrate solution is added to excess potassium chromate.

To determine the number of moles of AgNO3 present in 150 mL of a 0.500 M AgNO3 solution, we can use the formula:

moles = concentration × volume

Given:

Concentration of AgNO3 solution = 0.500 M

Volume of AgNO3 solution = 150 mL

First, we need to convert the volume from milliliters (mL) to liters (L) since the concentration is given in moles per liter (M).

1 L = 1000 mL

Therefore, the volume of the AgNO3 solution in liters is:

150 mL × (1 L / 1000 mL) = 0.150 L

Now we can calculate the moles of AgNO3 using the formula:

moles = concentration × volume

moles = 0.500 M × 0.150 L

moles = 0.075 mol

So, there are 0.075 moles of AgNO3 present in 150 mL of the 0.500 M AgNO3 solution.

Now, let's proceed to determine how many grams of solid silver chromate (Ag2CrO4) will precipitate when the AgNO3 solution reacts with excess potassium chromate (K2CrO4).

From the balanced chemical equation:

2AgNO3(aq) + K2CrO4(aq) → Ag2CrO4(s) + 2KNO3(aq)

We can see that the molar ratio between AgNO3 and Ag2CrO4 is 2:1. Therefore, for every 2 moles of AgNO3, we will form 1 mole of Ag2CrO4.

Since we have 0.075 moles of AgNO3, we can calculate the moles of Ag2CrO4 formed:

moles of Ag2CrO4 = 0.075 mol / 2 = 0.0375 mol

To determine the mass of Ag2CrO4, we need to multiply the moles by its molar mass. The molar mass of Ag2CrO4 is calculated by summing the atomic masses of each element in the compound:

Ag2CrO4 = 2(Ag) + 1(Cr) + 4(O) = 2(107.87 g/mol) + 1(52.00 g/mol) + 4(16.00 g/mol) = 331.87 g/mol

mass of Ag2CrO4 = moles of Ag2CrO4 × molar mass of Ag2CrO4

mass of Ag2CrO4 = 0.0375 mol × 331.87 g/mol = 12.45 g

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The final temperature of the water is equal to 44.1 °C when 137 ml of water at 25 °C is mixed with 82 ml of water at 76 °C.

The specific heat capacity of a substance is defined as the amount of energy required to raise the temperature of a substance by 1°C of one unit mass substance.

The equation of specific heat capacity is:

q = m. c. ΔT

Where q is the amount of heat gained or lost, m is the mass of the substance, and ΔT is the change in the temperature of the substance.

Since no heat is lost to the surroundings, then  \(Q_{before} = Q_{after}\)

Assuming the density of water is the same for both samples. Therefore, the ratio of the volumes of water will be equivalent to the ratio of their masses.

The equation used to calculate the final temperature (T) after mixing is:

\(T =\frac{m_1T_1+m_2T_2}{m_1+m_2}\)                                                           .................(1)

Given, m₁ = V₁ = 137 ml, m₂ = V₂= 82 ml, T₁ = 25°C and T₂ = 76 °C

Substitute the above values in the equation (1), to calculate the final temperature:

\(T=\frac{137\times 25 + 82\times 76}{137+ 82}\)  

\(T = \frac{9657}{219}\)

\(T = 44.1^oC\)

Therefore, the final temperature of the water is equal to 44.1 °C.

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The overall process is not spontaneous at standard-state conditions and 298 K.

Hence, The overall process is not spontaneous at standard-state conditions and 298 K.

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Answer:nucleus protons nuetrons electrons

Explanation:

The smallest partical into which an element can be divied and still be the smallest element

.( A basic unit o f matter)

Answer:

Nucleus, electrons, and protons

Explanation:

Multiple experiments and results accumulated over the years. Dalton is credited through his ray cathode tube experiments, and Rutherford's Gold Foil experiment led to the discovery of the positively charged nucleus and protons. His student Chadwick continued his studies and discovered the neutron.

\(▪▪▪▪▪▪▪▪▪▪▪▪▪ {\huge\mathfrak{Answer}}▪▪▪▪▪▪▪▪▪▪▪▪▪▪\)

Distance covered in 12 minutes = 18 km, now

Unit rate is equal to :

The train travels 1.5 km in 1 minute time interval.

Answer:

\(\huge\boxed{\sf 1\ minute = 1.5\ kilometers}\)

Explanation:

12 minutes = 18 kilometers

Divide both sides by 12

12/12 minutes = 18/12 kilometers

1 minute = 3/2 kilometers

1 minute = 1.5 kilometers

\(\rule[225]{225}{2}\)

Hope this helped!

All chemicals harm the environment. Therefore, the correct option is option A among all the given options.

Chemicals may contaminate the environment, including the food we consume, the water we drink, and the air we breathe. They may have infiltrated lakes and woods, wiping off fauna and altering the ecosystems. Not all chemicals are equally dangerous. Some dangerous substances are especially harmful to your health because of how prevalent they are in the environment and how poisonous they are.  All chemicals harm the environment.

Therefore, the correct option is option A.

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To prepare a 0.125 M solution of copper (II) oxide with a volume of 530.00 mL, you would need to calculate the mass of solid sodium nitrate required. The molar mass of sodium nitrate (NaNO3) is 85.0 g/mol.

To calculate the mass of solid sodium nitrate needed, you can use the formula:

Mass (g) = Molarity (mol/L) x Volume (L) x Molar Mass (g/mol)

Plugging in the values, we get:

Mass (g) = 0.125 mol/L x 0.530 L x 85.0 g/mol

Simplifying the equation gives:

Mass (g) = 5.31375 g

Therefore, approximately 5.31 grams of solid sodium nitrate must be used to prepare a 0.125 M solution of copper (II) oxide with a volume of 530.00 mL.

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A. The pH of the buffer solution is 4.38. B. pH of the buffer solution is 5.14 The buffer equation is given by: pH = pKa + log([A⁻]/[HA]), where pH is the desired pH of the buffer solution, pKa is the dissociation constant of the weak acid.

For the first solution, we have 0.67 moles of acetic acid and 0.33 moles of sodium acetate in 1 L of solution. To calculate the concentrations of the acid and the conjugate base, we first need to convert the moles to the corresponding masses:

mass of acetic acid = 0.67 mol x 60.05 g/mol = 40.23 g, mass of sodium acetate = 0.33 mol x 82.03 g/mol = 27.08 g The molarities of the acid and the conjugate base can be calculated by dividing the number of moles by the volume of the solution (1 L):

[HA] = 0.67 mol/1 L = 0.67 M, [A⁻] = 0.33 mol/1 L = 0.33 M. The dissociation constant (pKa) of acetic acid is 4.76. Substituting the values into the buffer equation, we get: pH = 4.76 + log(0.33/0.67), pH = 4.76 - 0.38 pH = 4.38. Therefore, the pH of the buffer solution is 4.38.

b) For the second solution, we have 0.33 moles of acetic acid and 0.67 moles of sodium acetate in 1 L of solution. Following the same procedure as above, we get: [HA] = 0.33 mol/1 L = 0.33 M,[A⁻] = 0.67 mol/1 L = 0.67 M

Substituting these values into the buffer equation, we get:pH = 4.76 + log(0.67/0.33) pH = 4.76 + 0.38, pH = 5.14. Therefore, the pH of the buffer solution is 5.14.

In both cases, the pH of the buffer solution is close to the pKa of acetic acid, which indicates that the buffer is working effectively to resist changes in pH when small amounts of acid or base are added.

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The total heat required to convert the ice to steam is 155,000 J.

The given parameters:

The heat required to raise the temperature to 0⁰C is calculated as;

\(Q = mc\Delta t\\\\Q_1 = 50 \times 4.184 \times (0 - (-10))\\\\Q_1 = 2092 \ J\)

The  heat required to melt the ice is calculated as follows;

\(Q_2 = mL_f\\\\Q_2 = 50 \times 333.55 \\\\Q_2 = 16,677.5 \ J\)

The heat raise the temperature to 100⁰C is calculated as;

\(Q_3 = 50 \times 4.184 \times (100 - 0)\\\\Q_3 = 20,920 \ J\)

The  heat required to boil the water is calculated as follows;

\(Q_4 = mL_v\\\\Q_4 = 50 \times 2230\\\\4_4 = 111,500 \ J\)

The heat raise the temperature to 120⁰C is calculated as;

\(Q_5 = 50 \times 4.184 \times (120 - 100)\\\\Q_5 = 4,184 \ J\)

The total heat required is calculated as follows;

\(Q_t = Q_1 + Q_2 + Q_3 + Q_4 + Q _5 \\\\Q_t = 2092 + 16,677.5 + 20,920 + 111,500 + 4,184\\\\Q_t = 155,373.5 \ J\\\\Q_t \approx 155,000 \ J\)

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It will take approximately 16.25 minutes for 650 mg of lidocaine to be administered at a rate of 4.0 ml/min. To find the time it takes to administer 650 mg of lidocaine, we need to use the given information.

Each 150 ml of IV contains 440 mg of lidocaine. Therefore, in 1 ml of IV, there are (440 mg / 150 ml) = 2.93 mg of lidocaine. Since the rate is set at 4.0 ml/min, the amount of lidocaine administered per minute would be (4.0 ml/min * 2.93 mg/ml) = 11.72 mg/min. To calculate the time it takes to administer 650 mg of lidocaine, we divide the desired amount (650 mg) by the rate (11.72 mg/min): 650 mg / 11.72 mg/min ≈ 55.50 min.

Therefore, it will take approximately 16.25 minutes for 650 mg of lidocaine to be administered at a rate of 4.0 ml/min.
The time it takes to administer 650 mg of lidocaine can be found using the given information. Each 150 ml of IV contains 440 mg of lidocaine, so in 1 ml of IV, there are 2.93 mg of lidocaine. The rate at which the IV is set is 4.0 ml/min. To find the amount of lidocaine administered per minute, we multiply the rate by the amount of lidocaine per ml, which equals 11.72 mg/min. To calculate the time it takes to administer 650 mg of lidocaine, we divide the desired amount by the rate, which gives us 55.50 min. Therefore, it will take approximately 16.25 minutes for 650 mg of lidocaine to be administered at a rate of 4.0 ml/min.

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Answer:

A. hibernation

Answer:

Hibernation.

Explanation:

The partial pressure of the hydrogen gas collected in this way is 710 mmHg. When collecting a gas over water, the total pressure of the system includes the vapor pressure of water at that temperature

When collecting a gas over water, the total pressure of the system is the sum of the partial pressure of the gas and the vapor pressure of water at that temperature. In this case, the total pressure is given as 742 mmHg, and the vapor pressure of water at 30°C is 31.8 mmHg.

To find the partial pressure of the hydrogen gas, we need to subtract the vapor pressure of water from the total pressure. Therefore, the partial pressure of the hydrogen gas can be calculated as:

Partial pressure of hydrogen gas = Total pressure - Vapor pressure of water

Partial pressure of hydrogen gas = 742 mmHg - 31.8 mmHg

Partial pressure of hydrogen gas = 710 mmHg

In this chemical reaction, the collected hydrogen gas exerts a partial pressure of 710 mmHg.

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91.7 mL mls of 0.600 m calcium chloride are needed to provide 0.110 moles of chloride ion for a reaction

250. mls of 0.600 m calcium chloride are needed to provide 0.150 moles of calcium ion for a reaction.

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The ratio of the mass of compounds:

a. 2Na + Cl\(_{2}\) → 2NaCl = 46 + 70 → 46 : 70

b. H\(_{2}\)O + NaO → 2NaOH = 1 : 8 + 23 : 16 → 23 : 16 : 1

c. HCl + NaOH → NaCl + H\(_{2}\)O = 1 : 35 + 23 : 35 → 23 : 35 + 1: 8

What is a  molecular mass?

Molecular mass refers to the total sum of the masses of the atoms or components that make up the molecule.

Calculation:

a. 2Na + Cl\(_{2}\) → 2NaCl

(Na x 2) + (Cl x 2) → (Na x 2) : (Cl x 2)

(23 x 2) + (35 x 2) → (23 x 2) : (35 x 2)

46 + 70 → 46 : 70

b. H\(_{2}\)O + NaO → 2NaOH

(H x 2) : (O x 1) + (Na x 1) : (O x 1) → (Na x 2) : (O x 2) : (H x 2)

(1 x 2) : (16 x 1) + (23 x 1) : (16 x 1) → (23 x 2) : (16 x 2) : (1 x 2)

2 : 16 + 23 : 16 → 46 : 32 : 2

1 : 8 + 23 : 16 → 23 : 16 : 1

c. HCl + NaOH → NaCl + H\(_{2}\)O

(H x 1) : (Cl x 1) + (Na x 1) : (Cl x 1) → (Na x 1) : (Cl x 1): (H x 2) : (O x 1)

(1 x 1) : (35 x 1) + (23 x 1) : (35 x 1) → (23 x 1) : (35 x 1) : (1 x 2) : (16 x 1)

1 : 35 + 23 : 35 → 23: 35 + 2: 16

1 : 35 + 23 : 35 → 23 : 35 + 1: 8

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