What are the answers to these?

Answer:

0.967mole

Explanation:

Given parameters:

Volume of NH₄Cl  = 21.67L

Unknown:

Number of moles  = ?

Solution:

We assume that the volume was taken at standard temperature and pressure,

 Then;

  Number of moles  = [tex]\frac{volume }{22.4L}[/tex]  

 Number of moles  = [tex]\frac{21.67}{22.4}[/tex]   = 0.967mole

In the given question, 136293840 seconds are present in 4.3 years.

A second is a unit of time that is equal to 1/60th of a minute and is used to measure short periods of time.

To convert 4.3 years to seconds, we can use the following conversion factors:

1 year = 365.25 days (accounting for leap years)

1 day = 24 hours

1 hour = 60 minutes

1 minute = 60 seconds

So, we can start by multiplying the number of years by the number of days per year:

4.3 years [tex]\times[/tex] 365.25 days/year = 1577.475 days

Next, we can multiply the number of days by the number of hours per day:

1577.475 days [tex]\times[/tex] 24 hours/day = 37859.4 hours

Then, we can multiply the number of hours by the number of minutes per hour:

37859.4 hours [tex]\times[/tex] 60 minutes/hour = 2271564 minutes

Finally, we can multiply the number of minutes by the number of seconds per minute to get the total number of seconds:

2271564 minutes [tex]\times[/tex] 60 seconds/minute = 136293840 seconds

Therefore, in 4.3 years there are approximately 136293840 seconds.

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Answer:

The number of formula units in 3.81 g of potassium chloride (KCl) is approximately 3.08 × 10²²

Explanation:

The given parameters is as follows;

The mass of potassium chloride produced in the chemical reaction (KCl) = 3.81 g

The required information = The number of formula units of potassium chloride (KCl)

The Molar Mass of KCl = 74.5513 g/mol

[tex]The \ number \ of \ moles \ of \ a \ substance, n = \dfrac{The \ mass \ of \ the substance}{The \ Molar \ Mass \ of \ the \ substance}[/tex]

Therefore, we have;

[tex]The \ number \ of \ moles \ of \ KCl= \dfrac{3.81 \ g}{74.5513 \ g/mol} \approx 0.051106 \ moles[/tex]

1 mole of a substance, contains Avogadro's number (6.022 × 10²³) of  formula units

Therefore;

0.051106 moles of KCl contains 0.051106 × 6.022 × 10²³  ≈ 3.077588 × 10²² formula units

From which we have, the number of formula units in 3.81 g of potassium chloride (KCl) ≈ 3.08 × 10²² formula units.

The number of formula units in 3.81 g of potassium chloride (KCl) is approximately 3.08 × 10²²

Given:

Mass of KCl= 3.81 g

To find:

Formula units of KCl=?

Molar Mass of KCl = 74.55 g/mol

So, substituting the values in order to calculate number of moles

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}} \\\\\text{Number of moles}=\frac{3.81}{74.55} \\\\\text{Number of moles}=0.051 \text{ moles}[/tex]

1 mole of a substance = Avogadro's number (6.022 × 10²³) of  formula units

Thus, 0.051 moles of KCl will contain

[tex]0.051106 * 6.022 * 10^{23} =3.077588 * 10^{22} \text{ formula units}[/tex]

→The number of formula units in 3.81 g of potassium chloride (KCl)

= 3.08 × 10²² formula units.

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Pair of compounds have the same empirical formula :C₂H₂ and C₆H₆

Given

Carbon compound

Required

The same empirical formula

Solution

The empirical formula is the smallest comparison of atoms of compound forming elements.  

A molecular formula is a formula that shows the number of atomic elements that make up a compound.  

(empirical formula) n = molecular formula  

C₂H₂ and C₆H₆

Empirical formula CH

(CH)₂=C₂H₂

(CH)₆=C₆H₆

C₂H₆ and C₃H₈

C₂H₆: Empirical formula CH₃

C₃H₈: Empirical formula C₃H₈

C₂H₅OH and CH₃OH ⇒ Empirical formula

CH₃CHO: Empirical formula : CH₃CHO

CH₃COOH: Empirical formula CH₂O

Answer:

(c) only solute present

Explanation:

In chemistry, the mole fraction, denoted by X, refers to the number of moles of a substance in a compound/mixture divided by the total number of substances in the same compound or mixture.

In this case, we can say that mole fraction represents the number of solutes to the number of solutes and solvent in the solution i.e. X = nA/nA + nB

Where; nA = number of solutes

nB = number of solvent

X = mole fraction.

Based on this analogy, When the mole fraction of solute is 1, there is only solute present. That is; X = 1 / 1 + 0

X = 1/1 = 1.

The given orbital diagram are iron and symbol for the element is Fe

Orbital diagrams are a pictorial description of electrons in an atom and where electron go in atom then we have to follow three rules, and the first one being the Auf bau Principle, the Auf bau Principle states that each electron occupies the lowest energy orbital  first filled and the second is pauli exclusion principle in which only two electron are present which is in opposite spin and third is hunds rule of maximum multiplicity in which pairing of electron is not possible until orbital are singly occupied this rules are used for filling the electron here given orbital diagram in which 1s²2s²2p⁶3s²3p⁶4s²3d⁶ means the element is iron and symbol of this element is Fe

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Answer:

The answer is B. Van der Waals forces are weaker than ionic and covalent bonds.

Explanation:

In general, if we arrange these molecular forces from the strongest to weakest, it would be like this:

Covalent bonds > Ionic bonds > Hydrogen bonds > Dipole-Dipole Interactions > Van der Waals forces

Covalent bonds are known to have the strongest and most stable bonds since they go deep and into the inter-molecular state. A diamond is an example of a compound with this characteristic bond.

Ionic bonds are the next strongest molecular bond following covalent bonds. This is due to the protons and electrons causing an electro-static force which results to the strong bonds. An example would be Sodium Chloride (NaCl), which when separated is Na⁺ and Cl⁻.

Van der Waals forces, also known as Dispersion forces, are the weakest type of molecular bonds. They are only formed through residual molecular attractions when molecules pass by each other. It doesn't even last long due to the uneven electron dispersion. It can be made stronger by adding more electrons in the molecule. This kind of molecular bonds appear in non-polar molecules such as carbon dioxide.

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The change that Hydrogen Bonds are most likely responsible for would be:

B). Causes salts to quickly dissolve in water.

Thus, option B is the correct answer.

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Answer:

xii. B. Smelting

xiii. D. Carbon

Explanation:

Smelting is known to be a process by which a metal is gotten. It is gotten either as the element or as a simple compound. This is obtained from metal's ore by heating. The heating can be done ordinarily in the presence of oxidizing agents, like air, or reducing agents, carbon e.g coke.

Zinc is gotten after Zinc oxide is heated in the presence of carbon.

This process is smelting.

Concentrated tetraoxosulphate acid is a strong dehydrating agent. It has the ability to char wood, paper, or sugar, leaving a carbonaceous residue. The charring effect is as a result of the carbon that is found in the wood.

The acid sucks in the oxygen and hydrogen, leaving behind the carbon; this results in the charring effect.

Answer:

Cr2O3

Explanation:

To find the empirical formula, which is the smallest whole number ratio of a compound, the following is done:

68.4% Cr = 68.4g of Chromium

31.6% O = 31.6g of Oxygen

Since, Cr = 52, O = 16, divide each mass by their respective atomic mass to convert to moles.

Cr = 68.4/52 = 1.315 mol

O = 31.6/16 = 1.975 mol

- Next, we divide each mole value by the smallest value (1.315mol)

Cr = 1.315/1.315 = 1

O = 1.975/1.315 = 1.50

The ratio or Cr to O is 1:1.5

We multiply this ratio by 2 to get the whole number ratio as follows:

2 × 1: 2 × 1.5

2:3

Hence, the empirical formula of Cr and oxygen is Cr2O3.

Answer:

1.55 x 10²⁴ formula units

Explanation:

Given parameters:

Number of moles of CaCl₂   = 2.58moles

Unknown:

Formula units in the compound  = ?

Solution:

To solve this problem, we must understand that;

    1 mole of a substance contains 6.02 x 10²³ formula units

   2.58 moles will contain 2.58 x  6.02 x 10²³ formula units  

                                            = 1.55 x 10²⁴ formula units

Answer:

λ  =  1.5 m

Explanation:

Given data:

Speed of wave = 1500 m/s

Frequency of sound = 1000 Hz

Wavelength of sound = ?

Solution:

Speed of wave = frequency × wavelength

by putting values,

1500 m/s  = 1000 Hz ×  λ

λ  =  1500 m/s  / 1000 s⁻¹     (Hz =  s⁻¹ )

λ  =  1.5 m

Answer: 1.5

Explanation:

Well first you do

1500/ 1000= 1.5 which mean

The wavelength is 1.5

Answer:

a.the same as

Explanation:

The temperature of each 400mL bucket is about the same as the temperature of the original bucket of paint.

This is because the temperature of the paint inside the bucket is not dependent on the amount of paint present.

Answer:

The postulate that all pure samples of a particular chemical compound contain the same elements  combined in the same proportion by mass.

Explanation:

The law of constant composition (or definite proportion) states that all pure samples of a particular chemical compound contain the same elements  combined in the same proportion by mass.

This law implies that irrespective of the source of the sample of the compound or the method by which the sample was prepared, as long as the sample is pure, the elements present in the compound are always combined in a specific ratio by mass. For example, water has the molecular formula H₂O. Irrespective of the water source, for example, tap-water, lake, stream, river or rainfall, each pure sample of water will have the constant composition of 2 atoms of hydrogen to one atom of oxygen.

The given compound exists as XO in nature. Therefore, irrespective of the source or method of preparation, every sample of this compound should have the formula XO. Since the compound prepared by the scientist was XO₂, therefore, the postulate that all pure samples of a particular chemical compound contain the same elements  combined in the same proportion by mass was violated by the scientist. The scientist must have prepared a different compound of the elemental compositions.

Answer:

because I make eggs and they taste delicious

Answer:

Conclusion

Explanation:

Answer:

O Trilobites

Explanation:

The first mass extinction that occurred between the Paleozoic and the Mesozoic era caused the extinction of the trilobites.

Extinction are catastrophic events that causes the loss of organisms on the earth surface. Several factors can lead to extinction.

Answer:

720 pencils

Explanation:

The parameter given are;

The unit quantity by which the pencils are sold = 1 gross

The number of pencils Daffodil orders = 5 gross of pencils

One gross is a quantity equal to twelve dozens

Therefore, we can write;

1 gross = 12 × 12 = 144

From which we have;

5 gross = 5 × 144 = 720

Which gives;

For the 5 gross of pencils Daffodil orders, she receives 720 pencils

Answer:

2Fe(s) + 3O2(g) --------> 2FeO3(s)

Explanation:

According to the question, a  battery was used  to light the steel wool by bringing the terminals very close together. When  the battery came into contact with the steel wool, current was sent out through the thin wire.  This caused the iron to heat up quite well.

Iron reacts with oxygen under these conditions as follows;

2Fe(s) + 3O2(g) --------> 2FeO3(s)

This is the chemical reaction that occurs when the steel wool is set on fire.

Chemical equation involved in Dr. Jeff's demonstration is

2 Fe+3 O₂[tex]\rightarrow[/tex]2 FeO₃

Battery is a device which helps in conduction of current. When a battery is used to pass a current through  a substance in this case which is steel wool made up of iron it starts getting heated up.

The amount by which substance gets heated up is directly proportional to the current passing through it. As more current is passed through the battery it gets heated more.

During heating, the iron present in the steel wool reacts with oxygen to form iron oxide with iron present in the+3 oxidation state.When the heat exceeds a certain point the steel wool catches fire due to the heat generated. The  heat causes the electrons present in steel wool of iron to move faster and collide with each other  thus generating more heat.

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Answer:

3

Explanation:

The molecular mass of gas = 44 g/mol

Given

5.6 Liters of gas

11 gram of gas

Required

The molecular mass

Solution

STP = Standart Temperature and Pressure , 1 atm 273 K

At STP , 1 mol gas = 22.4 L

So mol of 5.6 Liters gas :

= 5.6 : 22.4

= 0.25 moles

The molecular mass of gas :

= mass : mol

= 11 g : 0.25 moles

= 44 g/mol

Answer:

Oxygen receives two electrons from magnesium.

Explanation:

Hello!

In this case, considering the chemical reaction by which magnesium oxide is produced:

[tex]2Mg+O_2\rightarrow 2MgO[/tex]

In that case, if we show up the oxidation states, we have:

[tex]2Mg^0+O_2\rightarrow 2Mg^{2+}O^{2-}[/tex]

In such a way, since metals, like magnesium, have the capacity to lose electrons, rather than receive them, we infer why it turns out with +2 rather than -2; thus, we the correct answer is "oxygen receives two electrons from magnesium." because it results with -2 in MgO.

Best regards!

Answer:

Oxygen receives two electrons from magnesium.

Explanation:

Answer:

I think the answer would be B. hope this helps!!

Explanation:

Answer:

I'm not sure but I think the answer is electrons, protons and neutrons.

Answer:

There are three forces acting on the skateboard. One of these forces is the weight of the rider. Another is the force of gravity on the board itself. The third is the force of the ground pushing up on the skateboard.

Answer:

B. Controlled variables

Explanation:

The Dependent sample t-test compares the mean score of measurements in one group to that of another other group. It mainly used when analyzing comparable sample units as it pairs repeatable observations within a time frame.

Controlled variables are factors that are not tested and remain constant. Some examples of controlled variables are temperature, pressure, volume etc

Answer:

yes, some can

Explanation:

because like salt an other compounds by being decomposed

Answer:

answer is a because drugs do so to the person.

Explanation:

The prefix inter- means between, reflecting that interphase takes place between one mitotic (M) phase and the next. Image of the cell cycle. Interphase is composed of the G1 phase (cell growth), followed by the S phase (DNA synthesis), followed by the G2 phase (cell growth).