how many coefficients need to be changed to make this chemical equation balanced? Zn + HNO3 --> Zn (No3)2 + H2

Answer: F

Explanation: As we move from left to right in a period, electron affinity increases due to the increases in the effective nuclear charge.

However, it will not be easier to add an electron to a smaller atom. As we move in a group from top to bottom, electron affinity decreases but flourine has the smallest size in its group. So, on adding another electron externally to the valence shell causes severe electron-electron repulsion.

The wavelength should be 600 nm to minimize the interference from the presence of the CO{2+} ions (aq).

What is spectrophotometer?

An analytical tool called as spectrophotometer is used to determine the emission or reflection of visible light, UV light, or infrared light objectively.  These are used to calculate intensity as a function of light source wavelength.

The spectrophotometer available to the student has a wavelength range of 400 nm to 700 nm. The maximum wavelength for CO{2+} curve is 500 nm. The two curves of CO{2+} and Cu{2+} intersects at 600 nm.

So, 600 nm should the student use for interference minimization for the presence of CO{2+} ions.

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The molecular mass of the unknown compound found in the aqueous solution was 223.2g/mol

The sum of the atomic masses of all atoms in a molecule is called as molecular weight

So to get molar mass of the compound from the given weight the concentration of compound is elucidated and thereby leading to the calculation of molar mass

Then the concentration of solute in an aqueous solution can be derived from the osmotic pressure equation

So the osmotic pressure = van't hoff factor then the molarity of solute(M) gas constant(R) temprature(T)

From the given values in the question and applying constant values

8.44 torr = 1(for non electrolytes)× M×62.3637L⁻¹torr⁻¹mol⁻¹×298K

M = 4.54×10⁻⁴M

From the molarity of the given compound the molare mass can be calculated as

Molarity = weight/ molecular weight × 1000/volume(ml)

4.54×10⁻⁴M = 0..0152g/molecular weight × 1000/150ml)

Molecular weight = 223.2g/mol

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To calculate it using the formulas and learn about drug.

What is drug?

Drugs are by definition chemicals that, when ingested into a living system, influence or modify physiology. Both natural and artificial materials are acceptable. They are low-mass chemical structures, both in terms of atomic and molecular mass.

What is chemist?

At the atomic and molecular levels, chemists look into the characteristics of matter. They gauge proportions and reaction rates to better comprehend new substances and their behavior or to develop novel compounds for use in a variety of real-world scenarios.

Ratio of the compounds A and B are given as

compound A: compound B= 6:5

Now, chemist own to make a drug of 814ml, so we have to distribute these 814 ml in the ratio of 6:5. To make chemically correct drug.

Amount of compound=6/(6+5*814)

=6/11*814=444 ml

∴ Amount of compound a is needed 44 ml.

Therefore, 44 millimeters of a compound are needed.

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The pressure of the gas would now be 2/3 of its initial value.

We know that we can be able to use the ideal gas equation to be able to obtain the parameters that concern gases. In this case, we are dealing with the volume, temperature and volume all at once hence we need to use the general gas equation.

Initial pressure of the gas P1 = P

Final pressure of the gas P2 = ??

Initial volume of the gas V1 = V

Final volume of the gas V2 = 3V

Initial temperature of the gas T1 = T

Final temperature of the gas = 2T

P1V1/T1 = P2V2/T2

P1V1T2 = P2V2T1

P2 = P1V1T2/V2T1

P2 = P * V * 2T/3V * T

P2 = 2/3P

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A primary standard solid should be a very pure solid. NaOH does not meets this requirement because it is hygroscopic in nature.

A primary standard solid is a substance of known high purity (99.9% pure) which can be dissolved in a known volume of solvent that  results in a primary standard solution. Primary standards solutions  are reagents that are involved in chemical reactions. These compounds are often used to determine the unknown concentration of a solution that can undergo a chemical reaction with the primary standard compounds.

These compounds are extremely pure and are highly stable as well. Therefore, we can obtain pure solutions using these primary standard compounds.

Considering the case of NaOH, as it is hygroscopic in nature it attracts moisture from the air and its seen that its concentration keeps changing according to the environment around it and hence it cannot remain pure sample. Therefore we cannot rely on NaOH to the primary standard solid.

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The temperature in kelvin in a 0.0733 l bulb that contains 0.292 g of i2 vapor at a pressure of 0.462 atm is : T = 358.7K

Iodine is a chemical element with having symbol as I and atomic number is 53. It is the heaviest of the stable halogens and it exists as a semi-lustrous and non-metallic solid at standard conditions.

Given, volume (V) = 73.3mL = 73.3/1000 = 0.0733L;

and Mass of l2 = 0.292g;

and Pressure (P) = 0.462atm;

We have to find Temperature (T)

Mass of l2 = 0.292g

Molar Mass of I2 = 127 x 2 = 254g/mol

As we know that number of mole = Mass /Molar Mass

Hence, number of mole of I2 = 0.292/254

Number of mole of I2 = 1.15×10¯³ mole

The temperature in the bulb containing the iodine vapor can be found out by using the ideal gas equation as shown:

We know that, gas constant (R) = 0.0821 atm.L/Kmol

Using formula, PV = nRT

0.462 x 0.0733 = 1.15×10¯³ x 0.0821 x T

T = (0.462 x 0.0733)/(1.15×10¯³ x 0.0821)

Temperature  = 358.7K

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Answer: A. passes from one medium to another

Explanation: Light will change directions slightly forming a straight line.

Water different from most substances during phase changes because water changes into gaseous water or steam

Those portion of a system that are physically distinct and mechanically separable from other portion of the system are called phases and a phase change is occurring the liquid water is changing to gaseous water or steam and on molecular level the intermolecular forces between the water molecule are decreasing the heat is providing enough energy for the water molecule to overcome these attractive forces

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The molecules of two liquids mix together and form a new liquid. However, the liquid formed might be miscible or immiscible.

When two liquids are mixed together it forms a new solution. The new liquid has the properties of both of the original liquids.

The formed liquid may either be miscible or immiscible depending upon the properties of the two liquids.

Miscible liquids become homogeneous solutions so that their composition would be uniform. This is done by the complete diffusion of both liquids.

But in the case of immiscible liquids, the solution forms two separate layers giving out heterogeneous solutions.

Therefore, the combination of 2 liquids gives a new solution that could either be homogeneous or heterogeneous.

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An aqueous solution contains 0.33 m ammonia. one liter of this solution could be converted into a buffer by the addition of 0.16 mol of HBr.

A buffer is defined as the solution of weak base and salt of weak base and strong acid.

or it is also defined as the solution of weak acid and salt of weak acid and strong base.

In this given problem,

NH3 behave as a weak base. On the other hand, NH4OH behave as a salt of weak base and strong acid.

As we know that, NH3 react with strong acid to form NH4OH.

Chemical equation:

NH3 + HBr ------ NH4OH

or NH4OH + HBr ------- NH4Br + H2O

Thus, we concluded that an aqueous solution contains 0.33 m ammonia. one liter of this solution could be converted into a buffer by the addition of 0.16 mol of HBr.

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The percent yield of the reaction is 82%

First step: make the chemist equation.

2 Al (s) + Fe2O3 (s) → 2 Fe (s) + Al2O3 (s)

As the statement says that aluminium is in excess, the limiting reactant is the Fe₂O₃.

Second step: Find out the moles in the reactant.

Molar weight Fe2O3: 159.7 g/m

Mass / Molar weight = moles

50 g /159.7 g/m = 0.313 moles

Third step: Analyse the reaction. 1 mol of Fe2O3 makes 2 moles of Fe.

1 mol Fe2O3 ____ 2Fe

0.313 mol Fe2O3 ____ 0.626 moles

Molar weight Fe = 55.85 g/m

Moles . molar weight = mass

55.85g/m . 0.626m = 34.9 grams

This will be the 100% yield of the reaction but we only made 22.6 g

34.9 g ____ 100%

22.6 g ____ 64.75 %

Hence, the percent yield is 64.75 %.

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To filter runoff and stop soil erosion, locals are more likely to grow trees on their property alongside canals and roads.

What is soil erosion and what is its impact on water pollution?

Soil erosion is mostly caused by absence of trees, because the soil cannot hold itself. So if you add trees, there will be less soil erosion.

In addition to lowering soil productivity, soil erosion can have a substantial negative influence on water quality. In surface water bodies, sediment from soil erosion is a significant water quality problem. Reduced water quality is largely caused by increased amounts of phosphorus (P) and nitrogen (N) in surface waters.

When sediments are moved by soil erosion and surface water runoff, N,P can travel from fields into lakes and streams. The role of P- and N-rich sediment in creating eutrophication is one of the many issues that are frequently linked to soil erosion and sediment.

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You write the code chunk rename(Company...Maker.if.known. = Maker). The function that will modify the name of your column is rename().

The rename() function is used to rename a file or directory, from old name to new name, without altering the file's content. This function accepts the file's name as an argument. Renaming fields or reformatting their names is what the Rename Function is intended to do. Rename can be used for bulk renaming based on a JavaScript expression, or to change specific fields (much like the Eval Function). The rename command changes the name of the file or directory specified by oldname to the one specified by newname. The path to an already-existing file or directory must be in the old name. The name of an existing file or directory cannot be used as the new name.

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Answer:

Explanation:Statement number two and three are correct.Others are incorrect

Here we have been given statements relating to valence bond theory and lewis theory.

The 1st statement is incorrect.Because we use the valence electrons for bonding.

Valence bond theory is based on the partial overlapping.Therefore this statement is incorrect.

The second statement is correct.

Valence bond theory can make predictions about geometrical parameters like bond angle,bond length etc

Third statement is correct.

Lewis theory explains only electron dot structures.

Fourth statement is incorrect.

Valence bond theory explains bond formation due to overlapping between different molecules and the sharing of electrons.

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Number of bonding electron pair in SF5+ is 5 in number and non bonding electron pairs are 15 in the Lewis structure

Lewis dot structure also called as the electron dot structure are diagrams that describe the chemical bonding between atoms in a molecule. Along with that they also display the total number of electron pairs that are bonded to the atoms and also the electron pairs that are not bonded as well. Lewis structures extend the concept of the electron dot diagram by adding lines between atoms to represent shared pairs in a chemical bond.

In the above given question we need to find out the number of non bonding electron pairs and the bonding electron pairs of SF5+. This molecule is basically derived from SF6 molecule. When SF6 loosed one F atom it becomes SF5+. So we can see that the SF5+ has 5 bonding electron pair which are all bonded to the central S atom.

The non bonded electrons are present around the F atom to complete the valency. So each F atom has 3 pairs of electrons which means in total there are 15 non bonding electron pairs.

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As the lattice energy increases the size of the ionic solids will decrease.

Lattice energy can be defined as the energy required to convert one mole of an ionic solid into gaseous ionic constituents. Or else, it can also be defined as the energy that must be supplied to one mole of an ionic crystal in order to separate it into its  gaseous ions in a vacuum through an endothermic process.

However, it also suggests the energy that facilitates the dissociation of one mole of a solid ionic compound into its constituent gaseous ions.

Lattice energy is inversely proportional to the size of the ions. So as the size of the ions increases, the lattice energy of the compound will  decreases. Because as the size increases, the charge density gets distributed through out and so there is more distance between the electrons and hence the lattice energy will decrease.

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The reagent that will reduce an ester to an aldehyde is DIBAL-H  as a reducing agent and the reagent that will reduce an acid chloride to an aldehyde is LiAlH[OC(CH3)3]3

A reducing agent is typically is generally species that have lowest possible oxidation states, and is known as the electron donor. A reducing agent is oxidized itself, because it loses electrons during  the redox reaction.

According to the above cases given we can say that esters can be converted to aldehydes using diisobutylaluminum hydride (DIBAH). The reaction is usually carried out at -78 oC in order to prevent the formation of aldehyde as product.

Similarly Acid chlorides can be converted to aldehydes using lithium tri-tert-butoxyaluminum hydride (LiAlH(Ot-Bu)3).

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Answer: They are related to spring.

Explanation:

It should be right, I got this question correct.

Elements created in stellar nucleosynthesis are carbon, oxygen, iron, calcium .

What is stellar nucleosynthesis ?

Stellar nucleosynthesis is a process involving nuclear reactions in which new atomic nuclei are synthesized from existing nuclei or nucleons. The first stage of nucleosynthesis occurred in the hot early universe, producing H, He, and trace amounts of Li-7 (primordial nucleosynthesis). In today's universe, nucleosynthesis takes place as follows.

(1) thermonuclear reaction and explosion inside the star (nucleus formation up to the Fe peak), (2) neutron capture and explosion inside the star (nucleus formation above the Fe peak), (3) stars Spallation reactions in interstitial matter, where light nuclei (Li, Be, and B) arise from the fragmentation of heavy nuclei (C, N, and O).

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When we simplify a given equation we get a following answer

8 moles of HCl needed to produce 16 moles of magnesium Chloride

As per definition, mole is a same amount of number which contains same number of chemical species like atoms, molecules, ion, etc.

Mg   +    2HCl   →   MgCl2 + H2

1mole     2mole      1 mole    1 mole

Here, when 1 mole of Mg reacts with 2 mole of HCl then 1 mole of MgCl2 and 1 mole of H2 forms.

As per the question, to form 16 moles of MgCl2 we need 8 moles of HCl

to get our euqation done.

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This structure is incorrect because the octet rule is not fulfilled.

Lewis formulated the "octet rule" in his atom theory. The octet rule generally refers to the tendency of atoms in order to have eight electrons in the valence shell. When the atoms have fewer than eight electrons, they tend to react with other atoms and form more stable compounds. Usually atoms will react to get in the most stable state possible that is will try to satisfy the octet rule.

To find if octet is satisfied first we need to  determine the number of electrons from lone pairs and bonds to the atom. Each lone pair will donate  two valence electrons to the atom and each bond is represented by a line, gives two valence electrons to the atom. Second we need to confirm that the added up number of valence electrons is 8, or 2 for hydrogen.

In case of CO2 we can see that the octet rule is not satisfied so its the wrong structure.

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Answer:

Animals, during respiration, take in oxygen and release carbon dioxide gas. Plants, on the other hand, utilize this carbon dioxide gas in the process of photosynthesis to produce food and release oxygen in the atmosphere. Thus, we can say that plants and animals help each other in exchange of gases in the atmosphere.

Explanation:

because we can say that plants and animals help each other in exchange of gases in the atmosphere.

62.5 mL is prepare .

What is molarity?

Molar concentration is a unit of measurement for the concentration of a chemical species, specifically a solute, in a solution, expressed as the amount of substance per unit volume of solution. The most often used unit for molarity in chemistry is the number of moles per litre, denoted by the unit symbol mol/L or mol/dm3 in SI units.

Molarity of the stock solution as 0.100 M

Volume of the dilute solution as 250 mL

Molarity of dilute solution as 0.0250 M

We are required to calculate the Volume of the stalk solution.

Taking the volume and molarity of the stock solution to be V₁ and M₁ respectively, and volume and molarity of the dilute solution to be V₂ and M₂ respectively.

We are going to use the dilution formula;

According to the dilution formula, M₁V₁ = M₂V₂

Rearranging the formula;

V₁ = M₂V₂ ÷ M₁

   = (0.025 M × 0.25 L) ÷ 0.100 M

   = 0.0625 L

But, 1 L = 1000 mL

V₁ = 62.5 mL

Therefore, the volume of the stock solution is 62.5 mL

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what it takes to make 100 milliliters of 0.200 M solution out of Cu(NO3)2.4H2O.

A solution in chemistry is a uniform mixing of two or more substances in the appropriate ratios. Up to the solubility limit, the solution's make-up can be continuously modified. Although it is theoretically conceivable for gases and solids to form solutions, the term "solution" is typically used to describe the liquid state of matter.

The answer is the outcome of the solution. After resolving the issue, it is the specific value that you ultimately acquire. The solution is the method by which the final result is reached. It is a justification for the outcome.

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Answer:

High temperatures reduced the growth of tubers more than of shoots. Photosynthetic rates were unaffected or increased slightly at the higher temperature. Heat stress increased the accumulation of foliar sucrose and decreased starch accumulation in mature leaves but did not affect glucose.

Explanation:

i hope this helped <3

When 14. 8 grams of hydrogen is reacted with 34. 8 grams of oxygen. then water formed is 39.1935 grams.

A process that leads to the chemical transformation of one set of chemical substances to another is called a chemical reaction .

2H2 + 02 → 2H20

Given, mass of hydrogen = 14.8 grams

and we know molar mass of hydrogen = 2.02 g/mole

given, mass of oxygen = 34.8 grams

we know molar mass of oxygen = 32 g/mole

As we know that : moles is equal to mass / Molar mass

then, moles of hydrogen = 14.8g/ 2.02 g/mole = 7.33 moles

and moles of oxygen = 34.8g / 32g/mole = 1.0875 moles

For 2 moles hydrogen consumed, 1 mole of oxygen is needed.

This implies that oxygen is the limiting reagent and will be consumed completely.

We see that for 2 moles of H2 consumed,  1 mole of O2 is needed to produce 2 moles of H2O.

For 1.0875 moles of oxygen consumed, moles of H2O produced will be 2.175

We know, mass of H2O = moles of H2O * Molar mass of H2O

Hence, mass of H2O = 2.175 moles * 18.02 g/moles

Therefore, mass of H2O =39.1935 grams

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Answer:

AgNO3(aq) is the limiting reactant

Explanation:

Cu(s) = 2 moles

AgNO3(aq) = 250/169.87 that is the molar mass and we get 1.47 moles

1.47 < 2

The statement which describes a characteristic of a question that can be answered through scientific inquiry is that it can be answered using measurements.

This is referred to as a collection of quantitative or numerical data that describes a property of an object or a body. it has units which depicts the quantities which are present and an example is the unit of length being meter.

An example of a scientific method is experimentation which include different parameters. these parameters are mostly measured to get the actual values which makes it unique among other sets.

The features of a question that can be answered through scientific inquiry is that it can be answered using measurements because different values are getting and tested when dealing with a scientific method.

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