What is the job of a scientist?
A. To write laws based on his or her knowledge.
O
B. To ask and answer scientific questions.
C. To answer ethical questions.
O
D. To ignore facts that do not support his or her theory.

Answer:

5.82 ×10⁴ j

Explanation:

Given data:

Mass of water = 25.7 g

Amount of heat to evaporate it = ?

Molar heat of vaporization = 4.07×10⁴ j/mol

Solution:

First of all we will calculate the number of moles of water.

Number of moles = mass/ molar mass

Number of moles = 25.7 g/ 18 g/mol

Number of moles = 1.43 mol

Energy needed for one mole is 4.07×10⁴ j.

For 1.43 mol:

1.43 mol × 4.07×10⁴ j/ 1mol

5.82 ×10⁴ j

Answer:

Here are all of the answers for the page you are on

12.N - Atomic mass: 14.007 Atomic number: 7   outermost: 2P - Atomic mass: 30.974 Atomic number: 15 outermost: 3 As - Atomic mass: 74.922 Atomic number: 33 outermost: 4Sb - Atomic mass: 121.757 Atomic number: 51 outermost: 513.Mercury- Hg, 12, 6Iodine- 1, 7, 5Sodium- Na, 1, 3Nitrogen- N, 5, 214.K- potassium, metalSi- silicon, metallidS- Sulfur, nonmetal15.The Moseley chart was based on using the atomic mnumber of the element, not the chemical properties. Because of the similarities between elements of the same period, this often created problems in establishing an order; Moseley's work enabled the change of the atomic number from an arbitrary selection to a definable property, measurable through experimentation.

Explanation:

12.N - Atomic mass: 14.007 Atomic number: 7   outermost: 2P - Atomic mass: 30.974 Atomic number: 15 outermost: 3 As - Atomic mass: 74.922 Atomic number: 33 outermost: 4Sb - Atomic mass: 121.757 Atomic number: 51 outermost: 513.Mercury- Hg, 12, 6Iodine- 1, 7, 5Sodium- Na, 1, 3Nitrogen- N, 5, 214.K- potassium, metalSi- silicon, metallidS- Sulfur, nonmetal15.The Moseley chart was based on using the atomic mnumber of the element, not the chemical properties. Because of the similarities between elements of the same period, this often created problems in establishing an order; Moseley's work enabled the change of the atomic number from an arbitrary selection to a definable property, measurable through experimentation.

The chart used by Moseley was more accurate at predicting where new elements would be placed - due to fact that Moseley's chart was based on using the atomic number of the element, not the chemical properties or the atomic mass as Mendeleev.

Mendeleev's table had organized the elements by their atomic mass whereas Moseley's table had organized the elements by their atomic number.

Thus, due to fact that Moseley's chart was based on using the atomic number of the element, not the chemical properties or the atomic mass as Mendeleev.

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It shows how many atoms are in a element

A chemical formula shows you what a substance was made from. So like what elements are in it, and how many atoms of each element are in it.

For example: H20 has 2 atoms of hydrogen and 1 atom of oxygen.

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The amount of sugar in the milk chocolate bar, when reduced from 11.630 g to 4.000 g, would be approximately 3999 mg, assuming the sugar content scales directly with the weight of the chocolate bar.

To determine the amount of sugar in milligrams when the size of the milk chocolate bar is reduced from 11.630 g to 4.000 g, we must understand that the question implicitly suggests a direct relationship between the chocolate bar's weight and its sugar content. Assuming the sugar content scales directly with the weight, we can use a proportion based on the known values, while ensuring that our final answer is expressed in milligrams (mg) and to four significant figures.

First, we need the original sugar content in milligrams for the 11.630 g chocolate bar. Without this specific information, let's assume that the entire mass is sugar for demonstration purposes: 11.630 g equals 11630 mg (since 1 g = 1000 mg). If the bar is reduced to 4.000 g and the sugar scales directly, the amount of sugar in the reduced bar can be calculated as follows:

Answer:

Molecular oxygen and Hydrogen fluoride.

Explanation:

Definition:

Hydrogen bonding:

It is a type of dipole-dipole attraction between the hydrogen atom and more electronegative atoms.

In hydrogen bonding mostly the highly electronegative atoms are fluorine, nitrogen and oxygen.

Explanation:

In given compound such as methane CH₄ the electronegativity of carbon is 2.55 while that of hydrogen is 2.2 so there is smaller electronegativity difference that's why it can not form hydrogen bond.

In case of molecular oxygen the electronegativite atom oxygen is present. It can form hydrogen bonds with water. its electronegativity is 3.44.

In case of hydrogen fluoride the electronegativity atom fluorine is present. It will form hydrogen bonds with water. Its electronegativity is 3.98. So it is more likely to take part in hydrogen bonding.

Answer:

The atmosphere

Explanation:

study island

Answer:

They are in same group/family.

Explanation:

Alkaline earth metals are present in group 2 of periodic table. There are six elements in second group. Beryllium, magnesium, calcium, strontium, barium and radium.

All have two valance electrons but in different energy levels. Thus they have similar chemical properties.

Electronic configuration of calcium.

Ca = [Ar] 4s²

Electronic configuration of strontium.

Sr = [Kr] 5s²

They are present in group two and have same number of valance electrons (two valance electrons) and show oxidation state +2 by loosing two valance electrons. They also show similar reactivity.

They react with oxygen and form oxide.

2Sr  +   O₂   →    2SrO

2Ca +   O₂   →    2CaO

this oxide form hydroxide when react with water,

SrO  + H₂O   →  Sr(OH)₂

CaO  + H₂O   →  Ca(OH)₂

With sulfur,

Sr + S   →  SrS

Ca + S   →  CaS

Answer:

Explanation:To convert from cal/(g*C) to J/(kg*K), we just need to find a conversion factor for specific heat. There is really no mathematical way to do this other than to look in a physics or chemistry book and find a conversion factor. After doing this, you will see that 1 cal/(g*C) is equal to 4,186 J/(kg*K).

To find the specific heat of a material, first look at the units. There is energy per unit mass per unit temperature. So if we are given an amount of energy appllied to an object, its mass and how much the temperature of the object rises, we can calculate its specifc heat by dividing the energy by both the mass and the temperature, but don't forget to keep the units as they are:

Specific heat of the metal = (95 cal)/(10 K * 700g) = 0.014 cal/(g*K)

To find how much energy it requires to melt 250 grams of ice, we will need what is called the Latent Heat of Melting for ice. This is the amount of heat required to change unit mass of a solid into unit mass of a liquid at a constant temperature. Again, using a reference, the latent heat of melting for ice is found to be 334 kJ/kg. So the energy required to melt one kg of ice is 334 kJ. The amount of energy required to melt 0.250 kg of ice is then:

334 * 0.250 = 83.5 kJ

Option B

Primary productivity is not limited by time

Explanation:

To ecosystems, the productivity of the primary producers is essential because certain bodies generate energy for different existence bodies. Besides the era, primary production ends in the extension of dissimilar plant biomass to the practice. Consumers acquire their strength from primary producers, unless directly (herbivores, any detritivores), or diffusely.

It depends superimposed on the availability of the sunlight, availability of the nutrients such as nitrogen, iron, phosphorus from the soil and water. The primary productivity of the plant's distinct autotrophs is not restricted by time.

Answer:

its b i did the test

Explanation:

Answer:

1. Potential energy

2. Chemical energy

3. Electromagnetic energy

4. Kinetic energy

Answer:

1) potential energy 2) chemical energy 3) electromagnetic energy 4) kinetic energy

Explanation:

Just completed this question on my assignment. :)

Final answer:

A scientist questioning the energy mechanisms in newly discovered methanogenic bacteria might focus on metabolic pathways and evolutionary adaptations. Observations of motility in stab cultures and the isolation of penicillin by Alexander Fleming demonstrate the importance of empirical observation in microbiology.

Explanation:

When a scientist discovers a new bacterial species that is a methanogen, to better understand the evolution of mechanisms related to the capturing, storing, and using free energy in prokaryotes, the scientist might ask: "How does this methanogenic bacteria capture, store, and utilize free energy compared to other prokaryotes?" This question aims to investigate the metabolic pathways and energy transformation mechanisms that enable the bacteria to produce methane. It also allows for a broader comprehension of evolutionary processes and adaptation strategies among prokaryotes.

Concerning motility, observations in a stab culture could indicate bacterial motility if the bacteria have migrated away from the line of inoculation, suggesting that they might move by mechanisms such as flagella or cilia. An investigation to determine which household item has the most bacteria would involve swabbing the surfaces, culturing the collected samples, and then counting the colonies to compare the levels of bacterial presence. Hypotheses in this experiment would be based on the expected bacterial load of each item, and the results could validate or refute these suppositions.

Furthermore, Alexander Fleming's discovery of penicillin involved observing a zone of inhibition around a Penicillium mold in a culture of bacteria, which led him to theorize that the mold produced a substance lethal to the bacteria—leading to the isolation of penicillin.

Answer: [tex]2.9(10)^{7} ft[/tex]

Explanation:

Firstly we need to know that [tex]1 km=3280.84 ft[/tex], then we cam make the conversion:

[tex]8848 km \frac{3280.84 ft}{1 km}=29,028,872.32 ft[/tex] This is the height of Mount Everest in feet

However, we can express it using scientific notation by counting to the left the decimal spaces:

[tex]29,028,872.32 ft \approx 2.9(10)^{7} ft[/tex]

Explanation:

Answer: D

Explanation:

Answer:

n= -13

Explanation:

-22 = -9 + n

first flip the equation

n + -9 = -22

then add 9 beacuse we need to do the opposite to find n

so -22 + -9 = - 13

so n = -13

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Answer:

Mass = 27.4 g

Explanation:

Given data:

Mass of sulfur = 15.7 g

Mass of iron = ?

Solution:

Chemical equation:

Fe + S →  FeS

Number of moles of sulfur:

Number of moles = 15.7 g/32 g/mol

Number of moles = 0.49 mol

Now we will compare the moles of sulfur with iron

                  S         :        Fe

                  1          :         1

               0.49      :         0.49

Mass of iron:

Mass = number of moles  × molar mass

Mass = 0.49 mol× 55.85 g/mol

Mass = 27.4 g

Answer:

a

Explanation:

a

A)Models make systems more complicated and easier to learn.

Answer:

c.

Explanation:

When the temperature of a gas increases by 4x, its volume will increase according to option A, by 4x as per Charles's law. Thus, correct option is A.

If the pressure of a gas is decreased by 4x, the volume will increase as per option A, by 4x as per Boyle's Law. Thus, correct option is A.

According to the ideal gas law (PV = nRT), when the temperature of a gas is increased, keeping other factors constant, its volume also increases proportionally. This is known as Charles's law. So, if the temperature is increased by 4 times, the volume will increase by 4 times as well.

Similarly, according to Boyle's law, when pressure decreases, volume increases proportionally. So, if the pressure is decreased by 4 times, the volume will increase by 4 times.

Therefore, the correct answers are A for both scenarios.

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Final answer:

Both acetaldehyde and butanoic acid contain a carbonyl group (C=O), which is their similarity. Acetaldehyde is an aldehyde with the carbonyl group bonded to a hydrogen atom, and butanoic acid is a carboxylic acid with the carbonyl group bonded to an -OH group.

Explanation:

The question regarding acetaldehyde and butanoic acid pertains to the similarity of their functional groups. Both acetaldehyde and butanoic acid contain the carbonyl group (C=O). However, acetaldehyde is an aldehyde with the carbonyl group bonded to at least one hydrogen atom, giving it the formula CH3CHO, while butanoic acid is a carboxylic acid where the carbonyl group is bonded to an -OH group, giving it the formula C3H7COOH. Where they must have the same is in having the carbonyl group. Acetaldehyde acts as a starting material in the synthesis of many other organic compounds and occurs naturally in various foods; it also forms in the body during the metabolism of alcohol. On the other hand, butanoic acid has an unpleasant smell and is found in butter and animal fats. While both compounds are functionally different, their similar characteristic lies in the presence of the carbonyl group.

Acetaldehyde and butanoic acid both have a carbonyl group (C=O) in their structure.

Acetaldehyde and butanoic acid must have the same type of functional group known as the carbonyl group, which is denoted as C=O.

In acetaldehyde, the structure is CH₃CHO, where the carbonyl group is bonded to a hydrogen atom and a methyl group (CH₃). Butanoic acid, with the structure CH₃CH₂CH₂COOH, also contains a carbonyl group, but in this case, it is bonded to a hydroxyl group (OH) on the same carbon atom, characterizing it as a carboxylic acid.

The presence of the carbonyl group in both compounds facilitates similar reactions, such as the ability to form hydrates by adding water. This commonality is essential in understanding the fundamental properties and reactions of organic compounds in chemistry.

Answer:1 mole Li2O

Explanation: Solution attached

First balance the given chemical equation

4 Li + O2 => 2 Li2O

The stoichiometric factor of Li and Li2O is 4 moles Li and 2 moles Li2O

Solution:

2 moles Li x 2 moles Li2O / 4 moles Li

= 1 mole Li2O

Elements in group 2 have similar chemical properties due to the same number of valence electrons.

Explanation:

These are also known as alkaline earth metals. The Group 2 elements are 6 in number. This is the second most reactive elements after the alkali metals of group1.

These are group 2 elements because they contain 2 electrons in their valence shell.

They can easily form compounds by ionic bonds.

The elements in Group 2 have similar chemical properties because they have the same number of valence electrons in their atomic structure.

The elements in Group 2, also known as the alkaline earth metals, have similar chemical properties due to their atomic structure. Each element in Group 2 has two valence electrons in its outermost energy level. This similarity in valence electron configuration means that these elements have similar tendencies to lose two electrons and form +2 ions. For example, beryllium, magnesium, and calcium all readily form +2 ions by losing their two valence electrons. This similarity in chemical properties is due to the fact that elements in the same group have the same number of valence electrons.

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Answer:

3333333333333337ysh

After reaction, 20cm3 of oxygen will be left and 20cm3 of carbon dioxide will be produced. 12.5cm3 of 0.100 mol/dm3 copper(II) sulfate solution is required to react completely with a solution containing 0.0250 mol of sodium hydroxide.

In the experiment, 10cm3 of ethene (C2H4) was burnt in 50cm3 of oxygen. According to the equation (C2H4 + 3O2 = 2CO2 + 2H2O), every one molecule of ethene reacts with three molecules of oxygen to produce two molecules of carbon dioxide (CO2) and two molecules of water (H2O). As ethene and oxygen are both gases, we can apply the concept of stoichiometry in gases, and say that one volume of ethene will react with three volumes of oxygen, and produce two volumes of carbon dioxide. So, when 10cm3 of ethene burn, it will require 30cm3 of oxygen and produce 20cm3 of carbon dioxide. Hence, the remaining volume of oxygen is 50cm3 - 30cm3 = 20cm3 of oxygen.

As for the second problem, since one molecule of copper(II) sulfate (CuSO4) reacts with two molecules of sodium hydroxide (NaOH) according to the equation (CuSO4 + 2NaOH = Cu(OH)2 + Na2SO4), 0.0250 mol of NaOH would react with 0.0250 / 2 = 0.0125 mol of CuSO4. In terms of volume, that's 0.0125 mol * 1000cm3/mol = 12.5cm3 of 0.100 mol/dm3 copper(II) sulfate solution.

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Answer:

molecules P4O10 = 2.546 E22 molecules

Explanation:

∴ mass P4O10 = 12 g

∴ mm P4O10 = 283.886 g/mol

⇒ mol P4O10 = (12 g)×( mol/283.886 g) = 0.0423 mol P4O10

⇒ molecules P4O10 = (0.0423 mol P4O10)×(6.022 E23 molecules/mol)

⇒ molecules P4O10 = 2.546 E22 molecules

Answer:

This time, a hot metal spoon is put in room-temperature water.

Explanation:

The faster-moving atoms in the spoon contact the slower-moving molecules in the water. The atoms in the spoon transfer some of their energy to the molecules in the water. The spoon will get cooler and the water will get a little warmer.

Answer:

This time, a hot metal spoon is put in room-temperature water. The faster-moving atoms in the spoon contact the slower-moving molecules in the water. The atoms in the spoon transfer some of their energy to the molecules in the water. The spoon will get cooler and the water will get a little warmer.

Edit: this is what i think

Answer:

6.94 mol

Explanation:

Data given:

Mass of iron filings (Fe) = 388.3 g

no. of moles of iron (Fe) = ?

Solution:

For this formula will be used

       no. of moles = Mass in grams/ molar mass

molar mass of Fe = 56 g/mol

Put values in equation

                no. of moles = 388.3 g / 56 g/mol

                no. of moles = 6.94 mol

So,

no. of moles of iron in jar = 6.94 mol

The jar contains approximately 6.95 moles of iron.

The number of moles of a substance can be calculated using the formula:

moles = mass / molar mass

In this case, the mass of iron filings is given as 388.3 g. The molar mass of iron is 55.845 g/mol. By substituting these values into the formula, we get:

moles = 388.3 g / 55.845 g/mol = 6.95 mol

Therefore, the jar contains approximately 6.95 moles of iron.

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Answer

Cl2+2KI ➡ 2KCl + I2 is an example of redox reaction.

Explanation

While Iodine is being oxidized.

Oxidation addition of electronegative elements such as Chlorine or increase in oxidation number. Reduction, addition of electropositive elements such as Potassium metal or decrease in oxidation number.

Al2(SO4)3 + 3Ca(OH)2 -> 2Al(OH)3 + 3Ca(SO)4

Al[tex]_2[/tex](SO[tex]_4[/tex])[tex]_3[/tex]+ 3Ca(OH)[tex]_2[/tex] [tex]\rightarrow[/tex] 2Al(OH)[tex]_3[/tex]+ 3Ca(SO)[tex]_4[/tex] is the balanced equation. An imbalanced chemical equation describes the products and reactants of a chemical reaction.

A balanced equation is indeed a chemical reaction equation in which the overall charge and the amount of atoms for every element inside the reaction are the same for both the products and the reactants. In those other words, the mass plus charge on both side of the reaction are balanced.

An imbalanced chemical equation describes the products and reactants of a chemical reaction yet does not include the quantities needed to meet mass conservation. The balanced equation for the given reaction is Al[tex]_2[/tex](SO[tex]_4[/tex])[tex]_3[/tex]+ 3Ca(OH)[tex]_2[/tex] [tex]\rightarrow[/tex] 2Al(OH)[tex]_3[/tex]+ 3Ca(SO)[tex]_4[/tex].

Therefore, Al[tex]_2[/tex](SO[tex]_4[/tex])[tex]_3[/tex]+ 3Ca(OH)[tex]_2[/tex] [tex]\rightarrow[/tex] 2Al(OH)[tex]_3[/tex]+ 3Ca(SO)[tex]_4[/tex] is the balanced equation.

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Answer:

The "pressure gradient" causes the movement of air from high-pressure areas to low-pressure areas.

Explanation:

The pressure gradient is the physical entity which tells us about the direction of the air in which it will move. It also tells us about the rate at which it will increase as well as decrease in the specific location. The unit of the pressure gradient used is pascals per metre. The difference of this quantity creates uneven increase in the temperature of the surface of the Earth, only when the solar radiation focuses over the equator. They are also the reason behind the beginning movement of the air.

Answer:

wind

Explanation:

plato thank me later

Answer:A. Negative B. Positive C. Neutral or 0

Explanation: Electrons carries a negative charge and protons are apositively charge subatomic particles. Neutrons exhibits a neutral or 0 charge.

Answer:

The solubility of the organic amide product in the solvent hexane is 0.0403 moles/L at 0° C

Explanation:

When 2.85gm dissolved in 20ml of boiling solvent

After re crystallization 2.62gm was obtained

so, that the dissolved amount at 0° C is

2.85 - 2.62

= 0.23 gm in 20ml hexane

Mole of amide [tex]= \frac{0.23}{285.34} moles[/tex]

Solubility [tex]= \frac{0.23}{285.34} \times \frac{1000}{20}[/tex]

               = 0.0403 moles/L

Therefore, the solubility of the organic amide product in the solvent hexane is 0.0403 moles/L at 0° C