The Avogadro constant is defined as​

Answer:

Benzene must be kept away from flames.

Explanation:

Hello,

In this case since MSDS tables show the potential risks of chemical compounds, for benzene which which has a substantial vapor pressure and a fire rating of 3, which means that is highly flammable (very likely to get on fire), we conclude then that benzene must be kept away from flames due to its high risk. The other options are incorrect since it has 0 reactivity, it is nor fragile so it is not affected by shaking and it could be storage at standard pressures since it is a liquid at standard conditions as well.

Regards.

Answer:

Divide by 100

Explanation:

Answer:

The necklace is fake.

The necklace is made up of copper.

Explanation:

The following data were obtained from the question:

Mass of the necklace = 21.3 g

Volume of water = 5 mL

Volume of water + Necklace = 7.4 mL

To identify the composition of the necklace, we shall determine the density of the necklace.

This can be obtained as follow:

We'll begin by calculating the volume of the necklace. This can be obtained as shown below:

Volume of water = 5 mL

Volume of water + Necklace = 7.4 mL

Volume of Necklace =.?

Volume of Necklace = (Volume of water + Necklace) – (Volume of water)

Volume of Necklace = 7.4 – 5

Volume of Necklace = 2.4 mL

NOTE:

1 mL = 1 cm³

Therefore,

Volume of Necklace = 2.4 mL = 2.4 cm³

Finally, we shall determine the density of the necklace as follow:

Mass of the Necklace = 21.3 g

Volume of Necklace = 2.4 cm³

Density of Necklace =?

Density = mass /volume

Density = 21.3 / 2.4

Density = 8.87 g/cm³

Therefore, the density of the necklace is 8.87 g/cm³.

From the question given above, we were told Jacy bought a gold necklace.

But comparing the density of necklace to the densities given above the necklace is obviously made of copper material.

Therefore, Jacy bought a fake gold necklace.

Answer:

because if the hotness should more it will give it increase the temperature of earn water but it is not so because you have taken out hands from your and cold water So it is reliable

Answer:

the substance is element.

because an element is pure substance which is made of only one kind of atom.

Answer:

the diaphragm,the rib cage muscles and the abdominal muscles.

Explanation:

From a functional point of view, there are three groups of respiratory muscles: the diaphragm, the rib cage muscles and the abdominal muscles. Each group acts on the chest wall and its compartments, i.e. the lung-apposed rib cage, the diaphragm-apposed rib cage and the abdomen.

Answer:

(i). The elements that are likely to form a cation

(C). calcium, (D). barium, (E). cesium, (F). rubidium, (G).  lead and (H). scandium

(ii). The elements those that will always form ionic compounds in a 1:2 ratio with the halogens

(B).  lead, (G) barium and (I). calcium

Explanation:

Given that,

The following list of elements,

A. oxygen B. chlorine C. calcium D. barium E. cesium F. rubidium G. lead H. scandium I. phosphorous

We know that,

Cation is defined as, an element which is able to donate electron easily and obtained positive ion.

All metal elements able to form cations.

We need to find the elements that are likely to form a cation

Using given list

(C). calcium

(D). barium

(E). cesium    

(F). rubidium    

(G).  lead

(H). scandium

(II). The following list of elements,

A. phosphorous B. lead C. chlorine D. cesium E. rubidium F. scandium G. barium H. oxygen I. calcium  

We know that,

All given metal ions can form ionic compound with halogens as 1:2 ratio because all given metals can form +2 charge.

We need to calculate the elements those that will always form ionic compounds in a 1:2 ratio with the halogens

Using given list.

(B).  lead

(G) barium

(I). calcium

Hence, (i). The elements that are likely to form a cation

(C). calcium, (D). barium, (E). cesium, (F). rubidium, (G).  lead and (H). scandium

(ii). The elements those that will always form ionic compounds in a 1:2 ratio with the halogens

(B).  lead, (G) barium and (I). calcium

Answer:

We do something called hypothesis

Answer:

1. Make an observation.

2. Ask a question.

3. Propose a hypothesis.

4. Make predictions.

5. Test the predictions.

6. Iterate.

and if it can't be trsted the you did something wrong

Explanation:

The scientific method

At the core of biology and other sciences lies a problem-solving approach called the scientific method. The scientific method has five basic steps, plus one feedback step:

Make an observation.

Ask a question.

Form a hypothesis, or testable explanation.

Make a prediction based on the hypothesis.

Test the prediction.

Iterate: use the results to make new hypotheses or predictions.

The scientific method is used in all sciences—including chemistry, physics, geology, and psychology. The scientists in these fields ask different questions and perform different tests. However, they use the same core approach to find answers that are logical and supported by evidence.

Scientific method example: Failure to toast

Let's build some intuition for the scientific method by applying its steps to a practical problem from everyday life.

Explanation:

n=given mass ÷molar mass

make given mass become the subject of the formula by

multiplying the molar mass on both sides of the equation.

n=0.473mol

given mass=??

molar mass=48

therefore,given mass=n×molar mass

=0.473×48

=22.704grams

mass in grams is 22.704grams

The mass (in grams) of 0.473 mol of titanium is 22.6 grams.

We have some specific amount of moles of titanium.

We have to calculate the mass of given sample of titanium.

Titanium is a chemical element with the symbol Ti and atomic number 22. It is found in nature only as an oxide.

According to the question -

Moles of titanium - 0.473 moles.

Mass of 0.473 moles of titanium =

0.473 moles titanium x (47.87 grams titanium / 1 mole) = 22.6 grams

Hence,  the mass (in grams) of 0.473 mol of titanium is 22.6 grams.

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Answer:

all the below are ACIDS

Explanation:

1.HCOO- Formate

  HCOO- is a conjugate base.

2.HNO3- Nitric Acid

  Acid

3.CH3COOCH3: Methyl acetate

   Acid

4. HCOOH: Formic Acid

   Acid

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Answer:

36690

Explanation:

Answer:

Fluorine

Fluorine is the element in question, as its atomic number is 9 . You would name this particular isotope using the mass number. It would be called fluorine-19.

Explanation:

Answer:

Fluorine

Fluorine is the element in question, as its atomic number is 9 . You would name this particular isotope using the mass number. It would be called fluorine-19.

Answer:

pH = 1.683

Explanation:

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Answer:

A ; 20g of water has the least number of molecules

Explanation:

Here, we want to know which of the options represent the least number of molecules;

To calculate this, we are going to first calculate the number of moles using the formula below;

Number of moles = mass/molar mass

Then from the number of moles, we can calculate the number of molecules by multiplying the number of moles by 6.02 * 10^23 molecules

Let’s proceed;

a. That will be 20/18.02 = 1.1099 moles

1.1099 * 6.02 * 10^23 = 6.68 * 10^23 molecules

b. That will be 77/16.06 = 4.8 moles

4.8 * 6.02 * 10^23 = 2.89 * 10*24 molecules

c. That will be 68/42.09 = 1.62 moles

1.62 * 6.02 * 10^23 = 9.73 * 10^23 molecules

d. That will be 100/44.02 = 2.27 moles

2.27 * 6.02 * 10^23 = 1.37 * 10^24 molecules

e. That will be = 84/20.01 = 4.2 moles

4.2 * 6.02 * 10^23 = 2.53 * 10^24 molecules

From all the values obtained, the lowest is 20g of water

Answer:

B. what happens when iron rusts in the presence of water

Explanation:

Chemistry is a branch of science involving the composition and changes of matter. In other words, a chemist, who is a trained specialist in the science of chemistry, seeks to answer questions related to properties of matter.

In this question, a chemist is most likely to study "what happens when iron rusts in the presence of water" because it involves a change in the chemical properties of a substance (iron) i.e. a chemical change. However, what happens when ice melts to liquid water is a physical change.

Answer:

Yes, it is standard for each element. You can calculate it from the formula: n=A-Z, where n is the number of neutrons, A is the atomic mass and Z is the atomic number.

Answer:

The coordination number of ZrO₂ = 6

Explanation:

A crystal structure is determined by the ratio of ionic radii of the positive and negative ions present in the crystal.

The  ratio of the radii of the positive(cations) and negative(anions) is called the limiting radius ratio and it gives the coordination number of the crystal.

Limiting radius ratio = radius of cation/radius of anion

For ZrO₂:

radius of Zr ion (Zr⁴⁺) = 0.079 nm; radius of O ion (O²⁻) = 0.140 nm

Limiting radius ratio = 0.079 nm/0.140 nm = 0.564

From tables, when the limiting radius ratio value is between 0.414 - 0.732, the coordination number is six and the shape of the crystal is octahedral.

Therefore, the coordination number of ZrO₂ = 6

Answer:On a sloped parking lot

Explanation:

Answer:

To get a final result of experiments, an experiment is repeated several times and the result is noted every time to make sure the results are consistent.

Here the "consistent" meaning is either "same" or "nearby". Consistent results are required in experiments that show constant relation of an experiment to the same principles and the result is not different when performed the same experiment several times.

When performing the same experiment several times, the end result of each experiment should consistent means adhered to the same principle for a successful experiment.

Answer:

pH = 2.10

Explanation:

We name an acid as diprotic because it can release two protons:

H₂A  +  H₂O  ⇄  H₃O⁺   + HA⁻     Ka₁

HA⁻  +  H₂O  ⇄  H₃O⁺   + A⁻²      Ka₂

We propose the mass balance:

Analytical concentration = [H₂A] +  [HA⁻]  + [A⁻²]

As Ka₂ is so small, we avoid the [A⁻²] so:

0.18 M = [H₂A] +  [HA⁻]

But we can not avoid the HA⁻, because the Ka₁. Ka₁'s expression is:

Ka₁ = [H₃O⁺] . [HA⁻] / [H₂A]

We propose the charge balance:

[H₃O⁺] = [HA⁻] + [A⁻²] + [OH⁻]

As we did not consider the A⁻², we can miss the term and if

Kw = H⁺ . OH⁻

We replace Kw/H⁺ = OH⁻. So the new equation is:

[H₃O⁺] = [HA⁻] + Kw / [H₃O⁺]

The acid is so concentrated, so we can avoid the term with the Kw, so:

[H₃O⁺] = [HA⁻]

In the mass balance we would have:

0.18 M = [H₂A]

We replace at Ka₁

Ka₁ = [H₃O⁺] . [HA⁻] / [H₂A]

Ka1 . 0.18 / [H₃O⁺] = [HA⁻]

We replace at the charge balance:

[H₃O⁺] = Ka1 . 0.18 / [H₃O⁺]

[H₃O⁺]² = 3.4×10⁻⁴  . 0.18

[H₃O⁺] = √(3.4×10⁻⁴  . 0.18)

[H₃O⁺] = 7.82×10⁻³

- log [H₃O⁺] = pH → - log 7.82×10⁻³

pH = 2.10

Following are the calculation to the pH:

For First ionization:

[tex][H^+] = (K_{a1} \times C)^{\frac{1}{2}}[/tex]

where

C = initial concentration of acid [tex]= 0.18\ M[/tex]

[tex][H^{+}] = (3.4 \times 10^{-4} \times 0.18 \ M)^{\frac{1}{2}}\\[/tex]

[tex][H^{+}] = 0.007\ M[/tex]

For Second ionization:

[tex][H^{+}] = K_{a2} \\\\[/tex]

[tex][ H^{+} ] = 6.7 \times 10^{-9}\ M \\[/tex]

[tex]Total [H^{+}] = 0.007\ M + 6.7 \times 10^{-9}\ M\\\\Total [H^{+}] = 0.007 \ M[/tex]

[tex]pH = -\log[H^+] \\\\pH = -\log(0.007 \ M)\\\\pH = 2.15[/tex]

Therefore, the pH is "2.15".

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Answer:

Explanation:

calculate area of lawn

25  * 20  =  500  sq ft

calculate how many flakes fall per minute

500  *  1150  =   575 , 000  flakes/minute

convert per minute rate to per hour rate

575 , 000  * 60  = 34 ,500 , 000  flakes/hour

now you know how many flakes feel in that one hour so we can now weigh them

34 , 500 , 000  / 1.8  = 19 , 166 , 667  mg (rounded)

convert to kilograms

19 , 166 , 667 /  100 , 000  = 19.17  kg (rounded)

Answer:

Theoretical yield = 3.75g

Explanation:

Percent yield is defined as one hundred times the ratio between actual yield and theoretical yield. The expression is:

Percent yield = Actual Yield / Theoretical Yield * 100

In the problem, your actual yield was 3-00g.

Percent yield is 80.0%.

Solving for theoretical yield:

80% = 3.00g / Theoretical yield * 100

Theoretical yield = 3.00g / 80.0% * 100

Answer:

Ensure that the glassware is designed for heating

Check that there are no cracks in the glassware

Inspect the hot plate for frayed cords

Explanation:

All except measuring the height and width of the glassware could cause hazards within the lab.

Answer:

1 and a half cups

Explanation:

12 ounces is equivalent to 1.5 cups

Answer: .B. 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.

Explanation:

The statements that are true about 13C NMR are:

A. In 13C proton-decoupled NMR spectra, all peaks are singlets.

C 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.

D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry

Therefore, the option that isn't true is option B. "13C NMR spectra display peaks for only carbons that bear hydrogen atoms". This is false because 13C NMR will show every peak in the spectrum and it doesn't matter if it's only carbons that bear hydrogen atoms as everything will be shown.

Answer:

Explanation:

% mass of Ethylene glycol =(  mass of ethylene glycol/ mass of solution )x100%

                        =  62.1 g/ (62.1  +  250 )   x 100%

                       = 24.24%

Mass percentage is a term that represents the concentration, basically mass by mass percentage. It tells about the percentage of a component in a whole component. Therefore, the mass % of ethylene glycol is  24.24%.

Mass percentage represents the the percentage of each element that is making a particular compound. Mass percentage does not have any unit as numerator and denominator contains the same unit.

Mathematically,

Percentage of mass = (component’s mass ÷ total mass) x 100%

% mass of Ethylene glycol =(  mass of ethylene glycol/ mass of solution)x100%

% mass of Ethylene glycol =  62.1 g/ (62.1  +  250 )   x 100

                                             = 24.24%

Therefore, the mass % of ethylene glycol is  24.24%.

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Answer:

1.03

Explanation:

You would take 0.00103 and move the decimal like this; 0001.03, we wouldn't have the zeroes in front of the one, as it can throw us off. Therefore, your answer would be 1.03.

Hope I helped! Don't hesitate to let me know if I made a mistake.

Answer:

The temperature at which each bean is kept

Explanation:

Independent variable is what YOU CHANGE

The temperature at which each bean is kept is the independent variable.

INDEPENDENT VARIABLE:

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Answer:

mg

Explanation:

Answer: Attractive forces between particels

Explanation: