4. If the density of seawater at a depth of 10,000 m is 1.071 g/mL and a 25.0 g sample of water from that depth contains 99.7 mg K , what is the molarity of potassium ions in the sample

Answer:

a. Remaining at rest requires the use of ATP.

Explanation:

The resting membrane potential is maintained by the sodium-potassium pump. The sodium potassium pump does this by actively pumping sodium ions out of the cell and potassium ions inside the cell in a ratio of 3:2. This movement of ions by the sodium-potassium pump is against their concentration gradient. In a neuron at rest, there are more sodium ions outside the cell than there are inside the cell. Also, there are are more potassium ions inside the cell than there are outside the cell. However, there are ion channels through which these ions enter and leave the cell. Sodium ion channels allow sodium to enter the cell following its concentration gradient, whereas, potassium ion channels allow potassium to leave the cell following its concentration gradient. However, more potassium ions leave the cell than do sodium ions enter the cell because of the higher permeability of the cell to potassium ions.

In order to maintain the resting membrane potential, the sodium potassium pump powered by the hydrolysis of an ATP molecules pumps sodium ions out of the cell and potassium ions into the cell.

Therefore, the correct option is A, as ATP is needed by the sodium-potassium pump in order to maintain the resting membrane potential.

Answer:

145.8g

Explanation:

Given parameters:

Number of moles of magnesium hydroxide  = 2.5mol

Unknown:

Mass of Mg(OH)₂  = ?

Solution:

To solve this problem we use the expression below;

  Mass of Mg(OH)₂ = number of moles x molar mass

 Molar mass of Mg(OH)₂ = 24.3 + 2(16 + 1)  = 58.3g/mol

 Mass of Mg(OH)₂ = 2.5 x 58.3  = 145.8g

Answer:

As the oceans absorb more heat, sea surface temperature increases and the ocean circulation patterns that transport warm and cold water around the globe change

Explanation:

Answer:

[tex]neutrons_{Ga-69}=38\\\\neutrons_{Ga-71}=40[/tex]

Explanation:

Hello!

In this case, since isotopes of the same element have the same number of protons and electrons but different atomic mass, we can compute the number of neutrons by subtracting the number of protons to the atomic mass of the isotope; thus, for Ga-69 and Ga-71 (rounded up to whole numbers), we obtain:

[tex]neutrons_{Ga-69}=69-31=38\\\\neutrons_{Ga-71}=71-31=40[/tex]

Best regards!

Answer:

a- The paper towel with more thermal energy

Explanation:

The paper towel with a higher temperature is one with more thermal energy.

Temperature is the degree of hotness or coldness of a body. And it is a measure of the average kinetic energy of the particles within a medium or body.

As body gains more thermal energy which is a form of kinetic energy, the average kinetic energy of its particles increases.

This will in turn lead to an increase in the temperature of the substance.

So, the paper towel with more thermal energy will have a higher temperature.

Answer:

1.00 mole of any element has a mass numerically equal to its atomic mass in grams and contains 6.022×1023 particles.

Answer:

84.6g of nitrogen is the mass dissolved in a home aquarium

Explanation:

Using combined gas law:

PV = nRT

We can solve for the mass of nitrogen solving the total moles of the aquarium and with the mole fraction as follows:

P = 1.0atm

V = 93.0L

R = 0.082atmL/molK

T = 20°C + 273.15 = 293.15K Assuming room temperature as 20°C

PV / RT = n

1.0atm*93.0L / 0.082atmL/molK*293.15K

3.87 = moles of gas

As mole fraction of nitrogen in the air is 0.78, moles of nitrogen are:

3.87 * 0.78 = 3.02moles of nitrogen

As molar mass of nitrogen gas, N₂, is 28g/mol:

3.02 mol N₂ * (28g / mol) =

Answer:

(4) A bond is formed as energy is released.

Explanation:

Quizlet

A bond is formed as energy is released best describes the energy change in

the reaction.

Hydrogen atoms share their electrons to form a hydrogen molecule( H₂) .

Covalent bonds are the types of bonds formed when it occurs.

The formation of the bond results in energy being released. On the other

breaking of bonds involves energy to be absorbed. The stated facts

confirms  D as the most appropriate choice.

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Answer:

the middle and bottom left

Explanation:

one is a positively charged atom, and the other is normal. they are both the same

Answer:

the middle and bottom left .

Answer: Extinction

Animals on the verge of extinction are considered endangered species. Some could argue that the phrasing "threatened" is synonymous to "endangered". Some classify extinction based on if the species is completely wiped out in the wild, or if the species is completely gone (both in the wild and in zoos for instance). Extinction events are not solely due to the changes in atmosphere, but also due to lack of food or habitat, among other possible factors.

Answer:

Molecules

Explanation:

Answer:

Distance, direction and symbol.

Explanation:

Distance, direction and symbol are the three components of the map which make a complete description of a location. On the map, these three components are present which provides information about a specific location on the map. Map is a drawing on the paper that shows the geography of the whole world and provides information in detail.

Answer:

Apply some dishwashing solution with a white washcloth to the acetone residue and for a few minutes, work in gently from the edges of the spill to the center. Dont rub. Continue until the spill is completely removed.

The correct answer is B. meteorology. The study of weather is called meteorology, derived from the Greek word for "of the atmosphere".

Answer: More conservative scientists will try to modify the existing theory to fit the new data. The last answer, the fourth one.

Explanation: I think I had this question before, hope it helps!

Answer:

Sodium carbonate, Na₂CO₃ is the limiting

Explanation:

We'll begin by writing the balanced equation for the reaction between iron (iii) chloride, FeCl₃ and sodium carbonate, Na₂CO₃.

This is illustrated below:

2FeCl₃ + 3Na₂CO₃ → Fe₂(CO₃)₃ + 6NaCl

Next, we shall determine the masses of FeCl₃ and Na₂CO₃ that reacted from the balanced equation. This can be obtained as follow:

Molar mass of FeCl₃ = 56 + (3×35.5)

= 56 + 106.5

= 162.5 g/mol

Mass of FeCl₃ from the balanced equation = 2 × 162.5 = 325 g

Molar mass of Na₂CO₃ = (2×23) + 12 + (3×16)

= 46 + 12 + 48

= 106 g/mol

Mass of Na₂CO₃ from the balanced equation = 3 × 106 = 318 g

SUMMARY:

From the balanced equation above,

325 g of FeCl₃ reacted with 318 g of Na₂CO₃.

Finally, we shall determine the limiting reactant. This can be obtained as follow:

From the balanced equation above,

325 g of FeCl₃ reacted with 318 g of Na₂CO₃.

Therefore, 34.5 g of FeCl₃ will react with = (34.5 × 318)/325 = 33.76 g of Na₂CO₃.

From the calculations made above, we can see clearly that it will take a higher amount (i.e 33.76 g) of Na₂CO₃ than what was given (i.e 25.3 g) to react completely with 34.5 g of FeCl₃. Therefore, Na₂CO₃ is the limiting reactant and FeCl₃ is the excess reactant.

Answer:

False, they can interact without touching

Answer: 1. Oxygen is the the limiting reactant.

2. 7.52%

Explanation:

The balanced chemical equation is:

[tex]2H_2(g)+O_2(g)\rightarrow 2H_2O(g)[/tex]  

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]    

[tex]\text{Moles of} H_2=\frac{30.0g}{2g/mol}=15.0moles[/tex]

[tex]\text{Moles of} O_2=\frac{5.29g}{32g/mol}=0.165moles[/tex]

According to stoichiometry :

1 mole of [tex]O_2[/tex] require  = 2 moles of [tex]H_2[/tex]

Thus 0.165 moles of [tex]O_2[/tex] will require=[tex]\frac{2}{1}\times 0.165=0.331moles[/tex]  of [tex]NH_3[/tex]

Thus [tex]O_2[/tex] is the limiting reagent as it limits the formation of product and [tex]H_2[/tex] is the excess reagent.

2.  [tex]\text{Moles of} H_2=\frac{9.93g}{2g/mol}=4.96moles[/tex]

[tex]\text{Moles of} H_2O=\frac{6.72g}{18g/mol}=0.373moles[/tex]

As 2 moles of [tex]H_2[/tex] give = 2 moles of [tex]H_2O[/tex]

Thus 4.96 moles of [tex]H_2[/tex] give =[tex]\frac{2}{2}\times 4.96=4.96moles[/tex]  of [tex]H_2O[/tex]

percentage yield = [tex]\frac{\text {actual yield}}{\text {theoretical yield}}=\frac{0.373}{4.96}\times 100=7.52\%[/tex]

Thus the percent yield for the reaction is 7.52%

Answer:

14 hrs.

Explanation:

From the question given above, the following data were obtained:

Time (t) = 42 hrs

Original amount (N₀) = 4.32 g

Amount remaining (N) = 0.54 g

Half-life (t½) =…?

Next, we shall determine number of half-lives required for 4.32 g of the isotope to decay to 0.54 g. This can be obtained as follow:

Original amount (N₀) = 4.32 g

Amount remaining (N) = 0.54 g

Number of half-lives (n) =?

N = 1/2ⁿ × N₀

0.54 = 1/2ⁿ × 4.32

Cross multiply

0.54 × 2ⁿ = 4.32

Divide both side by 0.54

2ⁿ = 4.32 / 0.54

2ⁿ = 8

Express 8 in index form with 2 as the base

2ⁿ = 2³

n = 3

Thus, it took 3 half lives for 4.32 g of the isotope to decay to 0.54 g.

Finally, we shall determine the half-life of the isotope. This can be obtained as follow:

Time (t) = 42 h

Number of half-lives (n) = 3

Half-life (t½) =

n × t½ = t

3 × t½ = 42

Divide both side by 3

t½ = 42 / 3

t½ = 14 hrs

Thus, the half-life of the isotope is 14 hrs

Answer: C) middle 50 percent of the data

The interquartile range (IQR) spans from the first quartile Q1 to the third quartile Q3.

25% of the data is below Q1 and 75% of the data is below Q3. The gap between the two endpoints consists of 75-25 = 50 percent of the data, or half of the data.

The middle 50 percent of the data. Therefore, option (C) is correct.

The interquartile range (IQR) shows the spread or dispersion of a dataset. It is calculated as the difference between the third quartile (Q3) and the first quartile (Q1) in a sorted dataset. The first quartile (Q1) is the value below which 25 percent of the data falls, and the third quartile (Q3) is the value below which 75 percent of the data falls.

The interquartile range captures the range of the central 50 percent of the data. It provides a measure of the variability or spread of the middle portion of the dataset while excluding the influence of extreme values or outliers.

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Answer:

1- Hélium

2-protons

3-Electrons

4-2

Respectively thx

Answer:

warm blooded

Explanation:

humans are warm blooded. we cannot change our body temperature as we want to

Answer:

single replacement

Explanation:

I took the test :)

Cl₂ + 2KI → 2KCl + I₂ is an example of single replacement reaction. Therefore, option D is correct.

A single-replacement reaction is a chemical reaction in which one element replaces by the another in a compound. The general equation is. A + BC ⇒ AC + B.

An example of a single replacement reaction occurs when the element potassium  reacts with water, then the colorless solid compound  potassium hydroxide formed, and hydrogen gas is release. The equation for this reaction is as follows:

2K + 2H2O ⇒ 2KOH + H.

There are three main types of single replacement reactions are metal replacement, hydrogen replacement and halogen replacement reaction.

Thus, option D is correct.

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Answer:

Answer is explained below in the explanation section

Explanation:

Smaller signal is observed at a mass 1 amu because small percentage of the compound will have carbon isotope of 13C instead of 12C.

As we know, mass spectrometry is done as a small compound is first vaporized and then bombarded to ionize it. And then, those ions are accelerated forward and then at some point ions are separated and deflected by the application of magnetic field.

And finally hits the detector to give us a spectrum to read. So, in this whole procedure, there can be a small percentage of carbon isotope of 13C instead of 12C in that compound and showed in the spectrum as a smaller signal at a mass 1 amu.

Answer:

28.085

Explanation:

The formular to obtain average atomic mass unit from isotopes is given as;

sum of (Percentage abundance * Atomic mass) of all isotopes =  Average atomic mass unit

Silicon 28 = 92.23%

Silicon 29 = 4.67%

Silicon 30 = 3.1%

(92.23 / 100  *  27.977) + (4.67 / 100  *  28.976)  +  (3.1 / 100  * 29.974) = Average atomic mass

Average atomic  mass = 25.803 + 1.353 + 0.929 = 28.085

Explanation:

Cholesterol concentration = 27 mg/ 232 mL

Change unit mg/ml to kg/m³

1 kg = 1000 g

1 g = 1000 mg

1 kg = 1000000 mg

1 kg = 10⁶ mg

10⁶ mg = 1 kg

1 mg = 10^-6 kg

m³ = 1000 L

1 L = 1000 mL

m³ = 1000000 mL

m³ = 10⁶ mL

10⁶ mL = m³

1 mL = 10^-6 m³

Cholesterol concentration = 27 mg/ 232 mL

27 × 10^-6 kg/ 232 × 10^-6 m³

= 27/232 kg/m³

Answer:

[NH₄NO₃] at D → 0.279 M

Explanation:

This exercise involves a series of dilutions one after the other.

First of all, we calcualte ammonium nitrate's concentration at A.

15.71 g . 1 mol/ 80 g = 0.196 mol / 0.150 mL = 1.31 M

At B → 1.31 M . 20 mL/ 75 mL = 0.349  M

At C →  0.349 M . 15 mL / 25 mL = 0.209 M

[NH₄NO₃] at B = 0.349 M

[NH₄NO₃] at C = 0.209 M

So let's calculate the new moles

In 1 mL of B we have 0.349 mmoles

In 10 mL of B we have 3.49 mmoles

In 1 mL of C we have 0.209 mmoles

In 10 mL of C we have 2.09 mmoles

Volume of D = 10 ml + 10ml = 20 mL

Total mmmoles = 3.49 mmoles + 2.09 mmoles = 5.58 mmoles

[NH₄NO₃] at D = 5.58 mmoles / 20mL → 0.279 M