An unknown element X has the following isotopes: ²⁵X (80.5% abundant) and ²⁷X (19.5% abundant). What is the average atomic mass in amu of X?

The name of the covalent compound CCl₄  is carbon tetracloride while that of N₂O₅ is dinitrogen pentoxide.

Covalent compound has a covalent  bond which  is defined as a type of bond which is formed by the mutual sharing of electrons to form electron pairs between the two atoms.These electron pairs are called as bonding pairs or shared pair of electrons.

Due to the sharing of valence electrons , the atoms are able to achieve a stable electronic configuration . Covalent bonding involves many types of interactions like σ bonding,π bonding ,metal-to-metal bonding ,etc.

Sigma bonds are the strongest covalent bonds while the pi bonds are weaker covalent bonds .Covalent bonds are affected by electronegativities of the atoms present in the molecules.Compounds having covalent bonds have lower melting points as compared to those with ionic bonds.

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Answer:

74ifhdyteuyteutyruf

The question is incomplete, the complete question is;

Jia observes that adding a solution of sodium hydroxide to a clear liquid turns the liquid pink. She makes a hypothesis about why the liquid changed color.

Which characteristic is least important for her hypothesis to have?

A)ability to be tested

B)based on the opinion of her classmates

C)ability to be proven incorrect

D)based on her current knowledge

Answer:

B)based on the opinion of her classmates

Explanation:

A hypothesis is a supposition or tentative explanation put forward based on minimal evidence. It sometimes sets the pace for further investigation.

Hypothesis is always based on empirical observation and not on popular opinion, hence the opinion of Jia's classmates is least important in Jia's formulation of a hypothesis.

Answer:

B) based on the opinion of her classmates

Explanation:

edge 2023

Answer:CHEMICAL

Explanation:

it cannot go back to its original state and it reacts.

Explanation:

Hey there!!

The answer is Electrons.

Electrons are the small part of an atom that revolves around the nucleus of an atom.

Hope it helps..

Answer:

false, true, false - In reality stirring increases the speed of dissolving.

Answer:

False

True

False

Explanation:

1.It does take the shape of the container (has cohesive and adhesive properties)

2. It is a good solvent as in it, lots of salts are able to dissolve.

3. Stirring increases the speed of dissolving.

A variable within a scientific experiment is something that is changed (i.e. it varies). There should be only one manipulated variable within a scientific experiment so that the experimenter can be certain it is this variable which causes a pattern in the resultant data, if any exists at all.

HOPE IT HELPS PLZ BRAINLIEST

Answer:

Explanation:

The volume of a substance given the density and mass can be found by using the formula

[tex]volume = \frac{mass}{Density} [/tex]

From the question

Density = 13.5 g/cm³

We must first convert the mass from kg to g

1kg = 1000 g

mass of mercury = 1000 g

Substitute the values into the above formula and solve

That's

[tex]volume = \frac{1000}{13.5} [/tex]

We have the final answer as

Hope this helps you

Answer:

17.13mL

Explanation:

Complete question:

to give a pH of 7.32.

Hepes is a weak acid. When HEPES reacts with KOH its conjugate base, HEPES⁻ is produced:

HEPES + KOH → HEPES⁻

Now when you have in solution both the weak acid and conjugate base a buffer is produced. The equation that relates pKa and pH of a buffer is H-H equation:

pH = pKa + log [HEPES⁻] / [HEPES]

Where [] could be taken as the moles of each specie.

Replacing:

7.32 = 7.56 + log [HEPES⁻] / [HEPES]

-0.24 = log [HEPES⁻] / [HEPES]

0.57544 =  [HEPES⁻] / [HEPES] (1)

Now, moles of 5.250g of HEPES is:

Mass HEPES:

5.250g * (1mol / 238.306g) = 0.02203 moles HEPES.

That means:

0.02203 moles = [HEPES⁻] + [HEPES] (2)

Replacing (2) in (1):

0.57544 =  0.02203 moles - [HEPES] / [HEPES]

0.57544[HEPES] =  0.02203 moles - [HEPES]

1.57544[HEPES] = 0.02203 moles

[HEPES] = 0.01398 moles HEPES.

And [HEPES⁻] = 0.02203 moles - 0.01398 moles =

0.00805 moles of HEPES⁻

As HEPES⁻ is produced from HEPES and KOH, if we add 0.0805 moles of KOH, we will have in solution 0.00805 moles of HEPES⁻ and 0.01398 moles of HEPES.

To obtain 0.00805 moles of KOH from a 0.470M KOH, you need to add:

0.00805 moles KOH * (1L / 0.470mol) = 0.01713L of 0.470M KOH =

Answer:

Si14- Si^4+

As33- As^3-

Mg12- Mg^2+

Rb37- Rb^+

F9- F^-

Ge32- Ge^4+

Sn50- Sn^2+, Sn^4+

Explanation:

The elements shown in the answer have their common ions written beside them.

Silicon mostly forms positive ions in oxyacids and complex ions. Arsenic mostly forms its anion. Magnesium forms only the +2cation just as rubidium only forms the +1 cation. The fluoride ion is F^- while tin may for a +2*or +4 cation. Germanium usually forms the +4 cation.

Answer:

Which of the following is true about critical analysis of promotional claims?

a.  It is necessary because consumers generally do not need to purchase goods.

b.  Advertisements intend to mislead consumers about the goods they portray.

c.  It prevents consumers from purchasing unnecessary goods. Is Correct

d.  It is essential because advertisements always contain false information.

Critical analysis is an important aspect of the evaluation of the needs and demands. It is an integrated part of promotional claims to prevent unnecessary purchasing. Thus, option c is correct.

The promotional event is used in advertising to characterize the benefits and advantages of the services and products so as to persuade consumers and customers to buy the services and goods. The advertisements use claims to attract audiences.

It is a marketing strategy to increase sales and attract customers by offering various deals and services. The critical analysis of the promotional claim must be done to avoid the unnecessary purchasing of the goods and services by the consumers.

Therefore, option c. the unnecessary buying of the goods can be prevented by critical analysis.

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Answer:

Data obtained can't be accurate.

Explanation:

A beaker can't be used for measuring the volume of a liquid because they did not calculate volume of a liquid accurately and precisely. The marks present on the beaker are not accurate, it is just an estimate so by measuring the volume of any liquid using beaker give us a false data so that's why beaker are not used for the measurement of a volume.

Answer:

A. The solution with a pH of 2 will turn the litmus paper red

B. The solution with a pH of 8 will turn the China rose indicator green

C. The solution with a Ph of 7 will not change the color of the blue litmus indicator or of the China rose indicator

Explanation:

Blue litmus paper will only change color if it is dipped into an acidic mixture which turns it red. It will not change color at all in a basic or neutral Ph solution.

China rose turns dark pink in an acidic solution and green in a basic solution. However it has no change in color with a neutral solution.

Answer:

See explanation

Explanation:

The structures of maleic and fumaric acids are shown in the image attached to this answer.

We can easily see that maleoc and fumaric acids are geometric isomers of each other. They differ only in the orientation of the -COOH group about the C=C double bond.

Maleic acid is less stable than fumaric acid as shown by their respective heats of combustion. This is expected since maleic acid is the cis-isomer with more steric repulsion than the trans-isomer.

Maleic acid is more soluble than fumaric acid and also has a lower melting point than fumaric acid.

Answer:

The light emitted by a light bulb is a form of radiation that occurs when the filament heats up and its thermal emission gains enough energy to move into the visible spectrum.

Explanation:

Light bulbs contain a filament which is heated up electrically. When this filament is heated up,energy in the form of heat is imparted to the electrons in the filament.

This thermal excitation of electrons ultimately leads to emission of light in the viable spectrum. This light is now radiated through a light bulb.

Answer:

8.3 × 10¯¹¹

Explanation:

4.731×10¯⁷ ÷ 5.7×10³

The above expression can be simplified as follow:

4.731×10¯⁷ ÷ 5.7×10³

Recall

a^m ÷ a^n = a^(m – n)

4.731×10¯⁷ ÷ 5.7×10³ = (4.731 ÷5.7) × 10^(–7 – 3)

4.731×10¯⁷ ÷ 5.7×10³ = 0.83 × 10¯¹⁰

4.731×10¯⁷ ÷ 5.7×10³ = 8.3×10¯¹ × 10¯¹⁰

Recall

a^m × a^n = a^(m + n)

8.3×10¯¹ × 10¯¹⁰ = 8.3 × 10^(–1 + –10)

8.3×10¯¹ × 10¯¹⁰ = 8.3 × 10^(–1 – 10)

8.3×10¯¹ × 10¯¹⁰ = 8.3 × 10¯¹¹

Therefore,

4.731×10¯⁷ ÷ 5.7×10³ = 8.3 × 10¯¹¹

Answer:

1. d. Person A rounded their measurement

2) a. 105.

b. 76.4

c. 0.04

d. 1.988

Explanation:

1. Measuring an object is done with the least precise one. Person A recorded 1.5cm while Person B recorded 1.50cm of the same object. This measurement differs in the sense that Person A rounded up their measurement to 2 significant figures (1.5) while Person B recorded their answer as three significant figures (1.50).

2. During multiplication and division, the result is written as the measurement in the lowest significant figure.

a. 7.00 x 15.00 = 105. Calculator showed 105.00, which is 5 s.f (two zeros after decimal point are significant). The least significant figure is 3, hence 105.00 is rounded up to 105.

b. 40.2.1.901 = 76.4; The calculator answer of this operation is 76.420200 but since the lowest significant figure is 3. We round up our answer to 3 s.f i.e. 76.4

c. (0.003)(13.2) = 0.04. For this operation, calculator answer is 0.0396, however, the lowest significant figure in the question is 1 i.e. 0.003. Note that the two zeros before 3 are insignificant. Hence, our answer will be rounded up to 1 s.f i.e. 0.04

d. 1.590+ 0.3975 = 1.988. the calculator answer to this operation is 1.9875. However, the least significant figure in the question is 4 i.e. 1.590. hence, the answer will be rounded up to 4 s.f which is 1.988.

Answer:

Surface tension

Capillary action

Explanation:

Surface tension is the force acting along the surface of the liquid causing the liquid surface to behave like a stretched elastic skin. Surface tension causes the water drops that fall on a smooth surface to form rounded drops or beads.

If you touch a piece of paper to the drop, water appears to move up into the paper on its own due to capillarity. Capillarity is the tendency of a liquid to rise or fall in a narrow tube.

Answer:

D. release of carbon dioxide on heating limestone

Answer:

The guy up there is wrong cause i literally just took this test and the answer is B. cellular respiration in humans

Explanation:

Answer:

64cm^3

Explanation:

[tex]s = 4cm\\V = s^3\\\\V = 4^3\\V =4\times 4\times 4\times 4\\Volume = 64cm^3[/tex]

Answer:

1 True

2. True

3. True

4. True

5. False

Explanation:

1. Hypochlorous acid (HOCl)  is a weak acid that forms when chlorine dissolves in water, and is partially dissociated, forming hypochlorite. HOCl is considered a strong oxidizing agent responsible for the killing action of germs in chlorine solutions.

2. Acetic acid is also known as ethanoic acid. It has a distinctive sour taste and pungent smell, and is generally considered a weak acid. in a concentrated form, acetic acid can be corrosive.

3/4 . Methylene chloride is an organochloride compound with the formula CH2Cl2. It is  a colorless, volatile liquid with a moderately sweet aroma is widely used as a solvent. It is normally stable, non-flammable and non-explosive when mixed with air at temperatures below 100 °C, but its vapor is flammable only when present in relatively high concentrations of about 14% to 22% in air. Research shows that it is very much possibly carcinogenic, and it has been linked to cancer of the lungs, liver, pancreas, breast cancer and salivary gland cancer in laboratory animals.

5. Laboratory and medical waste are not to be disposed in the trash with regular wastes, as they are potentially toxic. Special disposal methods and agencies exists to take away such wastes.

Answer:

No no no and no no no no no no

Answer:

This is quite a controversial question ahaha. Personally, I think pineapple on pizza is good sometimes. depends on the day though.

Explanation:

To me it is a good combination of sweet and salty. The pineapple is also pretty refreshing.

Answer:

Density, [tex]d=1.235\ g/cm^3[/tex]

Explanation:

It is given that, the density is 1,235 kg/m³.

We need to convert the density to g/cm³.

We know that,

1 kg = 1000 g

1 m = 100 cm

[tex]1235\ kg/m^3=1235\ \dfrac{kg}{m^3} \\\\=1235\times \dfrac{1000\ g}{(100\ cm)^3}\\\\=1.235\ g/cm^3[/tex]

So, the density is [tex]1.235\ g/cm^3[/tex].

Answer:

Explanation:

Homogeneous mixture is a mixture in which the components of the mixture are in the same proportion throughout any sample extracted from the mixture while an heterogeneous mixture is a mixture in which the components of the mixture differ in term of proportion when different samples of the mixture are extracted and compared.

For example, a sandy water will have some parts (usually the bottom) of the mixture with more sand than other parts of the mixture, hence, it (sandy water) is a heterogeneous mixture. While salty and ocean water has it's salt dissolved in the same proportion throughout the water in the mixture, hence salty and/or ocean water is a homogeneous mixture.

Sandy water can be separated by filtration (i.e using a filter paper to separate the sand from the water when the mixture is poured over a filter paper) while salty and ocean water can be separated by distillation (i.e boiling of the mixture so the water molecules can boil and move through a tube as gas or steam into another container where they are cooled and converted back to liquid or water while leaving the solid salt component of the mixture in the boiling tube).

Answer:

Avogadro number of pennies will extend to a distance of 6.02 * 10¹⁷ km

Note: The question is missing some parts. The complete question is as follows;

A penny has a thickness of approximately 1.0 mm . If you stack ed Avogadro's number of pennies one on top of the other on Earth 's surface, how far would the stack extend (in km)? [For comparison, the sun is about 150 million km from Earth and the nearest star (Proxim a Centauri) is about 40 trillion km from Earth.]

Explanation:

Avogadro number = 6.02 * 10²³

thickness of a penny = 1.0 mm

I mm = 0.001 m

Thickness of Avogadro number of pennies stacked one upon another will be:

6.02 * 10²³ * 0.001 m = 6.02 * 10²⁰ m

Distance in km;

1 m = 0.001 km

therefore, 6.02 * 10²⁰ m = 6.02 * 10²⁰ * 0.001 km = 6.02 * 10¹⁷ km

Avogadro number of pennies will extend to a distance of 6.02 * 10¹⁷ km

Answer:

The correct options are B and D

Explanation:

A physical property is a property (of any substance) that can be observed without the substance undergoing any change in identity nor does it require a chemical reaction to determine. For example, colour and size are physical properties that are part of the identity of a substance and can/must be observed without a substance undergoing any change or chemical reaction. This explanation makes option A wrong and option D right.

A chemical property of a substance is the property that relies on the ability of that substance to undergo a chemical reaction/interaction with another substance to form a new/different substance. For example, ability of a substance to react with an acid (to form a different substance) is a chemical property. This explanation makes option C wrong and option B correct.

Answer:

Substances which are non heat-resistant and volatile organic liquid with flammable vapor.

Explanation:

Bunsen Burner are used as a source of fire in the laboratory for heating up substances. Extra care however should be taken during heating in order to prevent fire or other forms of accidents.

Heating of mind heat resistant substances should be frowned at as the substances may get heated up and melt thereby exposing the liquid substances which may be flammable to fire thereby causing fire outbreak.

Heating of volatile organic liquid with flammable vapor should also be discouraged to prevent fire accidents.