Can someone help me
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The question is incomplete, the complete question is;

The half-life of strontium-90 is about 29 years. How many half-lives have elapsed when 6.25% of a strontium- 90 sample remains in the container?

Answer:

4 half lives

Explanation:

From;

N/No = (1/2)^t/t1/2

N= amount of strontium-90 present at time t

No= amount of strontium-90 originally present

t= time taken

t1/2 = half life of strontium-90

But N= 0.0625No

Hence;

0.0625No/No = (1/2)^t/29

0.0625 = (1/2)^t/29

(1/2)^4 = (1/2)^t/29

4 = t/29

t = 4 × 29

t= 116 years

Hence four half lives have elapsed

Answer:

1. AlCl₃

2. CuSO4

3. Zn(NO₃)₂

4. (NH4)2CO3

Answer:

D. The pressure of the gas decreases!

Explanation:

According to Boyle's Law, there is an inverse relationship between the volume of a gas and its pressure!

So, if the volume of a gas increases, its pressure will decrease; the same thing will happen if the pressure of the gas increases -- the volume will decrease!

↑P↓V and ↓P↑V    <---- this is what it would look like visually!!

Hope this helps! :)

When the volume of a gas increases then the pressure of the gas decreases.

Ideal gas equation is a hypothesis which tells about the behavior of gas in different conditions and it will be represented as:
PV = nRT

From this equation it is clear that pressure and volume are inversely proportional to each other:
P ∝ 1/V

Means if pressure increases ten volume decreases or if pressure decreases then volume increases.

Hence option (4) is correct.

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Answer:

La presión que ejerce es 42 atm.

Explanation:

La ley de Boyle relaciona la presión y el volumen y dice que  el volumen ocupado por una determinada masa gaseosa a temperatura constante, es inversamente proporcional a la presión.

La ley de Boyle se expresa matemáticamente como:

P*V=k

Ahora es posible suponer que tienes un cierto volumen de gas V1 que se encuentra a una presión P1 al comienzo del experimento. Si varias el volumen de gas hasta un nuevo valor V2, entonces la presión cambiará a P2, y se cumplirá:

P1*V1= P2*V2

En este caso:

Reemplazando:

3 atm* 7 L= P2* 0.5 L

Resolviendo:

[tex]P2=\frac{3 atm*7 L}{0.5 L}[/tex]

P2= 42 atm

La presión que ejerce es 42 atm.

Answer:10.5

Explanation:

3atm x 7L / 0,5L = 10.5

Quando bajamos el volmen sube la presion y cuando bajamos la presion sube el volumen

Answer:

[tex]M_b = \frac{0.10M * 9.50mL}{3.80mL}[/tex] ---- The setup

[tex]M_b = 0.25M[/tex] --- The molarity of KOH

Explanation:

Given

I will answer the question with the attached titration data

Required

The set and the value of the molarity of KOH

First, calculate the volume of acid (HCL) used:

[tex]V_a = Final\ Reading - Initial\ Reading[/tex]

[tex]V_a = 25.00mL - 15.50mL[/tex]

[tex]V_a = 9.50mL[/tex]

Calculate the final volume of base (KOH) used:

[tex]V_b = Final\ Reading - Initial\ Reading[/tex]

[tex]V_b = 8.80mL - 5.00mL[/tex]

[tex]V_b = 3.80mL[/tex]

The numerical setup is calculated using::

[tex]M_a * V_a = M_b * V_b[/tex]

Where

[tex]V_a = 9.50mL[/tex]

[tex]V_b = 3.80mL[/tex]

[tex]M_a = 0.10M[/tex] --- the given molarity of HCL

So, we have:

[tex]M_a * V_a = M_b * V_b[/tex]

[tex]0.10M * 9.50mL = M_b * 3.80mL[/tex]

Make Mb the subject

[tex]M_b = \frac{0.10M * 9.50mL}{3.80mL}[/tex] ---- The correct numerical setup

The solution is then calculated as:

[tex]M_b = \frac{0.10M * 9.50mL}{3.80mL}[/tex]

[tex]M_b = \frac{0.10 * 9.50}{3.80}M[/tex]

[tex]M_b = \frac{0.95}{3.80}M[/tex]

[tex]M_b = 0.25M[/tex]

electrons

protons

atom

compounds

mixtures

Answer:

B

Explanation:

Answer:

88,88 % de O y 11,11 % de H

Explanation:

La composición porcentual se define como la masa que hay de cada mol de átomo en 100g. Las moles de agua en 100g son:

Masa molar agua:

2H = 2*1g/mol = 2g/mol

1O = 1*16g/mol = 16g/mol

Masa molar = 2 + 16 = 18g/mol

100g H2O * (1mol / 18g) = 5.556 moles H2O.

Moles de hidrógeno:

5.556 moles H2O * (2mol H / 1mol H2O) = 11.11 moles H

Moles Oxígeno = Moles H2O = 5.556 moles

La masa de hidrógeno es:

11.11mol * (1g/mol) 11.11g H

La masa de oxígeno es:

5.556 mol * (16g / 1mol) = 88.89g O

Así, el porcentaje de O es 88.89% y el de H es 11.11%. La opción correcta es:

Answer: The total energy, in kilojoules, that is needed to turn a 46 g block of ice at -25 degrees C into water vapor at 100 degrees C is 11.787 kJ.

Explanation:

Given: Mass = 46 g

Initial temperature = [tex]-25^{o}C[/tex]

Final temperature = [tex]100^{o}C[/tex]

Specific heat capacity of ice = 2.05 [tex]J/g^{o}C[/tex]

Formula used to calculate the energy is as follows.

[tex]q = m \times C \times (T_{2} - T_{1})[/tex]

where,

q = heat energy

m = mass

C = specific heat capacity

[tex]T_{1}[/tex] = initial temperature

[tex]T_{2}[/tex] = final temperature

Substitute the values into above formula as follows.

[tex]q = m \times C \times (T_{2} - T_{1})\\= 46 g \times 2.05 J/g^{o}C \times (100 - (-25))^{o}C\\= 11787.5 J (1 J = 0.001 kJ)\\= 11.787 kJ[/tex]

Thus, we can conclude that the total energy, in kilojoules, that is needed to turn a 46 g block of ice at -25 degrees C into water vapor at 100 degrees C is 11.787 kJ.

Answer:

b

Explanation:

cause empirical formular is the elementary or the foundation for molecular formula and molecular formula depends on the empirical formula

Answer: i'm pretty sure it's b if i remember correctly.

Explanation:

i learned this a while ago so i'm not completely sure.

Answer:

fractional distillation since ot depends on the different liquids to have different boiling points

Answer:

9

Explanation:

pH = -log[H+] = -log(1x10^9) = 9

Answer:

Liquid and gas is the matter that takes shape of a container

It can also be called fluid since fluid is distributed into liquid and gas

Explanation:

I hope that is enough for your answer, hope this will help

Answer:

8 OH⁻(aq) + Mn(s) ⇒ MnO₄⁻(aq) + 4 H₂O(l) + 7 e⁻

Explanation:

Let's consider the following oxidation half-reaction that takes place in basic aqueous solution.

Mn(s) ⇒ MnO₄⁻(aq)

First, we will perform the mass balance. We will add 4 H₂O to the products side and 8 OH⁻ to the reactants side.

8 OH⁻(aq) + Mn(s) ⇒ MnO₄⁻(aq) + 4 H₂O(l)

Finally, we will perform the charge balance by adding 7 electrons to the products side.

8 OH⁻(aq) + Mn(s) ⇒ MnO₄⁻(aq) + 4 H₂O(l) + 7 e⁻

Answer:

Part A

Given that the graph is symmetrical and bell shaped, the average kinetic energy is given by the midline of graph, which corresponds to the common speed of the highest number of the population

Part B

The formula for the average kinetic energy, K.E. = (3/2)·(R/NA)·T

Therefore, the part of the graph that indicates the temperature of the sample is the average kinetic energy. K.E.

Part C

At a lower temperature, the heat is less evenly distributed and we have the distribution T2 higher than T1

Please see the attached graph created with MS Visio

Explanation:

Answer:

Typical organic fertilizers include mineral sources, all animal waste including meat processing, manure, slurry, and guano, plant based fertilizers, such as compost, and biosolids.

Answer:When trying to concentrate the solution by evaporation to produce waterless sulfurous acid it will decompose

Explanation:

Explanation:

here's the answer to your question

Option first 2.52 atm

Answer:

Solution given:

pressure 1[P1]=2.8atm

pressure 2[P2]=?

temperature [T1]=400k

temperature [T2]=360k

now

By using gas equation

P1V1/T1=P2V2/T2

since

volume is constant

P1/T1=P2/T2

2.8/400=P2/360

P2=2.8*360/400

P2= 2.52

Answer:

It's 2.52

Explanation:

This requires Gay-Lussac's Law, in which the relationship is P1 / T1 = P2 / T2. "P" stands for Pressure and "T" is Temperature. The first pressure is 2.80, the first temperature is 400 Kelvin, the second pressure is unknown (that's what your solving for), and your second temperature is 360 Kelvin. Because you don't have the second pressure, your equation will look like 2.80 atm x 360 K / 400. This will tell you that the pressure of the gas at 360 K will be 2.52.

I also took the test and it was correct.

Answer:

1. (a) delivered volume, (b) to reach, (a) moles

2. (c) molar ratio

3. (b) acid solution before.

Explanation:

1. You must titrate the acid with a base solution of known concentration, and use the (a) delivered volume. At the endpoint, the moles of acid and base in the titration follows the chemical equation, thus, you need (b) to reach the endpoint. With volume and concentration of the base we can find its (a) moles

2. With the (c) molar ratio, we can relate the moles of base with the moles of acid

3. When we have the moles of acid, we just need the volume of (b) acid solution before the titration to find molarity of the acid.

Answer:

combustion

Explanation:

bsnszisb idiej jeiieyv

Answer:

Option D is good to go!

Explanation: as per the reactivity series more reactive substances will react with the counterpart substance.The most reactive substance here is calcium while the least reactive is aluminium, the magnesium comes in between.As per their reactivity, these substances will react with oxygen.

Explanation:

from

HCl + NaOH----> NaCl +H2O

n of acid=1

n of base=1

Molarity of acid=750M

Molarity of base=290M

volume of base=25ml

from

Va=Mb ×vb×na

Ma×nb

Va=290×25×1

750×1

Va=7250

750

Va=9.67ml

The volume of .750 M hydrochloride acid is required to react completely with 25.00 mL of .290 M NaOH solution is 9.67ml

HCl + NaOH----> NaCl +H2O

n of acid=1

n of base=1

Molarity of acid=750M

Molarity of base=290M

volume of base=25ml

Therefore,

Va=Mb ×vb×na

Ma×nb

Va=290×25×1

750×1

Va=7250

750

Hence,

Va=9.67ml

Hydrochloric acid, also known as muriatic acid, is an aqueous solution of hydrogen chloride. It is a colorless solution with a distinctively pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the digestive systems of most animal species, including humans. Hydrochloric acid is an important laboratory reagent and industrial chemical.

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Answer:

0.86812566700000000000000

The binomial expansion of (1+2x)^7in ascending power of x is 0.868125.

The algebraic expression (x + y)n can be expanded according to the binomial theorem, which represents it as a sum of terms using separate exponents of the variables x and y.

Each word in a binomial expansion has a coefficient, which is a numerical value. A binomial is a two-term algebraic expression. Examples of binomials include a + b, x - y, and more.

When a binomial is raised to exponents 2 and 3, we can use a set of algebraic identities to determine the expansion. As an illustration, (a + b)2 = a2 + 2ab + b2.

By regrouping and combining like phrases, we can arrange our final response in ascending powers of x by placing the lowest power of x first and the highest power of x last.

Therefore, the binomial expansion of (1+2x)^7in ascending power of x is 0.868125.

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The systematic name for PbO₂ is lead dioxide.Therefore, the correct option is A.

Systematic names are a type of chemical nomenclature that follow a systematic set of rules to name chemical compounds. Lead dioxide (PbO₂) is a chemical compound composed of lead and oxygen. It is an oxide of lead and can also be called lead(IV) oxide.

The systematic name of the compound is derived by using the root word of the metal, “lead,” and adding the suffix “-dioxide” to indicate the two oxygen atoms. Thus, the systematic name for PbO₂ is lead-dioxide.Therefore, the correct option is A.

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The question is incomplete, but most probably the complete question is,

Give the systematic name for PbO₂?

A. Lead dioxide

B. Lead trioxide

C. Lead oxide

D. Lead azide