Which of the following is a testable hypothesis?

A. If I brush my teeth, I will get fewer cavities than if I don't brush my
teeth.

B. Green toothpaste tastes better than blue toothpaste or red
toothpaste.

C. Smart, careful, healthy people always brush their teeth.

D. It's wrong to not brush your teeth before you have an important
conversation with someone.

Answer:

6.47 x 10⁵.

Explanation:

The results are reported to the fewest significant  figures.

So, the result should has 3 significant figures:

(2.08 x 10³)(3.11 x 10²) = 6.4688 x 10⁵.

• In a series of calculations, carry the extra digits through to  the final result, then round.

• If the digit to be removed :

✓ is less than 5, the preceding digit stays the same.

For example, 1.33 rounds to 1.3.

✓ is equal to or greater than 5, the preceding digit is

increased by 1. For example, 1.36 rounds to 1.4.

So, the result will be 6.4688 x 10⁵ = 6.47 x 10⁵.

Final answer:

To solve (2.08 \times 10³) (3.11 \times 10²), multiply the decimal parts, add the exponents, and express the answer to three significant figures, resulting in 6.47 \times 10⁵.

Explanation:

To solve the problem (2.08 \times 10³) (3.11 \times 10²), we need to multiply the two numbers, taking into account the exponent rules and significant figures.

Firstly, multiply the decimal numbers:

2.08 \times 3.11 = 6.4688

Next, add the exponents of 10:

10^3 \times 10² = 10⁽³⁺²⁾ = 10⁵

Now combine the two results:

6.4688 \times 10⁵

However, we need to express the answer to the correct number of significant figures. The first number has three significant figures while the second number has three significant figures, so our final answer should also have three significant figures.

The result should be rounded to:

6.47 \times 10⁵

We have rounded the number 6.4688 to 6.47 to match the three significant figures. This is our final answer, expressed in proper scientific notation with the correct number of significant figures and proper units.

Answer:

No heat is released.

Explanation:

A substance absorbs heat when it melts.

The formula for the heat absorbed is

[tex]q = m\Delta_{\text{fus}}H[/tex]

Data:

m = 10 g

\Delta_{fus) H=\text{334 J/g}

Calculations:

[tex]q = 10 \times 334 = \text{3340 J = 3.34 kJ}\\\text{The ice }\boxed{\textbf{absorbs 3.34 kJ}} \text{ when it melts}.[/tex]

The energy released when the given mass of the ice melts is 3,340 J.

The energy released when the given mass of the ice melts is determined by taking the product of mass and heat of fusion of the ice.

Q = mH

where;

Substitute the given parameters and solve for the energy released when the ice melts.

Q = 10 x 334

Q = 3,340 J

Thus, the energy released when the given mass of the ice melts is 3,340 J.

Learn more about heat released here: https://brainly.com/question/13439286

Answer:

Explanation:

I usually just use approximate values for the elements on the periodic table. The reason for that is that everyone uses a different periodic table. Some are rounded others are more precise. Redo this problem with better numbers for the elements.

N = 14

H = 1

N2H4 = 2*14 + 4*1  

N2H4 = 28 + 4 = 32

If you are given 31 grams of N2H4 then the formula is

mols = given mass / molecular mass

mols = 31 / 32

moles = 0.97  

Now you have a problem . Is the answer 1.0 or is 0.9?

I think I would pick 1.0

Zn(s) + 2HCl (aq) -----> ZnCl​​​2 (aq) + H​​​​​​2 (g)

Here rate of reaction depends upon twice of the concentration of HCl.

Thus if concentration of HCl is lowered, rate of the reaction will be lowered and less ZnCl​2 will be produced.

Thus answer is (B) The reaction will be slow down.

Answer:

A very large amount of energy is produced from a very small mass.

Explanation:

Nuclear energy is produced either by fusion or fission. The former is the fusion of lighter atoms into heavier elements while the latter is the splitting of a heavier atom into lighter atoms. Both produce tremendous amounts of energy. Fusion, causes compaction of mass while fission reduces it. Fusion does not produce radioactive particles while fission does (alpha and beta particles and neutrons).

Answer:

A) it can measure data by experiments

Explanation:

Chemistry is testable which means that when a scientist claims a certain observation happening in chemical sciences then other chemists globally can verify that observation by carrying out independent experiments. When similar observations are made only then there is a consensus in the scientific community.

Therefore, chemistry is testable

Learn more at: https://brainly.com/question/17756498?referrer=searchResults

Answer:

A lunar eclipse occurs when the Moon enters the Earth's shadow. A solar eclipse occurs when the Moon's shadow falls on the Earth. They do not happen every month because the Earth's orbit around the sun is not in the same plane as the Moon's orbit around the Earth.

Answer:

0.5

Explanation:

1 mole of ammonium nitrate contains 2 moles of nirogen

1 mole of nitrogen converts to 0.5  moles of ammonium nitrate

the conversation factor is 0.5

Answer:

The conversion factor is 0.5, with which we have to multiply moles of nitrogen to convert it into moles of ammonium nitrate.

Explanation:

As given the molecular formula of ammonium nitrate is NH₄NO₃

There are two nitrogen in each molecule.

thus in each mole of ammonium nitrate there are two moles of nitrogen present in it.

It means if there are two moles of nitrogen the mole of ammonium nitrate will be one

If there is one mole of nitrogen the moles of ammonium nitrate is 0.5.

So if we wish to convert moles of nitrogen to moles of ammonium nitrate we have to multiply the moles of nitrogen with 0.5.

The conversion factor is

[tex]\frac{molesofammoniumnitrate}{molesofnitrogen}=0.5[/tex]

Answer:

False

Explanation:

Max Planck's theory of the duality of energy shows that the frequency radiation "v" can be regenerated only if an oscillator of such frequency has acquired the minimum energy required to initiate oscillation. At low temperatures, there is not enough energy available to induce high-frequency oscillations; in this way, the object does not regenerate ultraviolet radiation, ending the ultraviolet catastrophe.

Albert Einstein used this Max Planck hypothesis to explain the results obtained in his work on the photoelectric effect in 1905. Einstein did not refute Max's theory.

Albert Einstein's discovery of quanta does not disprove Max Planck's hypothesis about the dual nature of energy   i.e. False

Max Planck's hypothesis ( quantum hypothesis ) on the radiation of a black body states that energy from light can only be absorbed and radiated in discrete bundles ( quanta ), and this formed the basis on which Albert Einstein explained the results he obtained from his photo electric effect experiment he carried out.  therefore we can conclude that Einstein did not disprove Max Planck's hypothesis.

Hence we can conclude that Albert Einstein's discovery of quanta did not disprove Max Planck's hypothesis about the dual nature of energy.

Learn more : https://brainly.com/question/14439631

Answer:

1) 0.0625  g.

2) 0.0125 g.

Explanation:

1) A solution of NaOH has a concentration of 25.00% by mass. What mass of NaOH is present in 0.250 g of this solution?

mass% of NaOH = [(mass of NaOH)/(mass of solution)] x 100.

mass% of NaOH = 25.0%, mass of NaOH = ???  g, mass of solution = 0.250 g.

∴ mass of NaOH = (mass% of NaOH)(mass of solution)/100 = (25.0%)(0.250 g)/100 = 0.0625  g.

2) What mass of NaOH must be added to the solution to increase the concentration to 30.00% by mass?

We can use the relation:

mass% of NaOH = [(mass of NaOH)/(mass of solution)] x 100.

mass% of NaOH = 30.0%, mass of NaOH = ???  g, mass of solution = 0.250 g.

∴ mass of NaOH = (mass% of NaOH)(mass of solution)/100 = (30.0%)(0.250 g)/100 = 0.075  g.

∴ The mass of NaOH should be added = 0.075 - 0.0625 = 0.0125 g.

Answer:

1) 0.0625  g.

2) 0.0125 g.

3) 80.0 g

Explanation:

edge

Answer:

50%

Explanation:

You would have to do 15 divided by 30 x 100 to get 50

Percentage Yield = Actual Yield divided by Theoretical Yield

Hope this is right and helpful

Answer:

12000 Liters or 12 × 10^6 cubic centimeters

Explanation:

Multiply the volume value by 264.172

Please mark brainliest and have a great day!

Answer:

c. 5 × 10⁴ barleycorn

Explanation:

It is given that:

1 barleycorn = 1/3 of an inch

Convert 1 barleycorn into meter (m) units

1 inch = 2.54 cm

since 100 cm = 1 m

1 inch = 0.0254 m

Therefore 1/3 of an inch = [tex]\frac{1}{3} *0.0254 = 0.00847 m[/tex]

therefore:

1 barleycorn = 8.47*10⁻³ m

The height of the empire state building of 449 m would be:

[tex]=\frac{1\ barleycorn*449 m}{8.47*10^{-3} m} = 5.3*10^{4}\ barleycorn[/tex]

Final answer:

The height of the Empire State Building, when converted from 449 meters to barleycorns, is approximately 53,040 barleycorns, which corresponds to the option c. 5 × 10⁴ barleycorns.

Explanation:

To convert the height of the Empire State Building from meters to barleycorns, we follow a two-step process. First, we convert the meters to inches, and then we convert the inches to barleycorns.

The Empire State Building is 449 meters tall. To convert meters to inches, we use the conversion rate, where 1 meter is approximately 39.37 inches.

Next, since 1 barleycorn is equal to 1/3 of an inch, we divide the number of inches by 1/3 to find the number of barleycorns:

When rounded to the nearest integer, we get 53,040 barleycorns, which corresponds to option c. 5 × 104 barleycorns.

Answer:

the strongest intermolecular forces

Explanation:

The broken lines depicts hydrogen bonding. Hydrogen bonds are intermolecular forces are they are very strong bonds. These bonds are special dipole-dipole attractions between polar molecules in which hydrogen atom is directly joined to a highly electronegative atom usually oxygen or nitrogen or fluorine.

The broken lines shows the intermolecular attraction.

Answer: In Thomson's model, the atom is composed of electrons called “corpuscles,” he calls the model the plum pudding model of the atom

(pls mark me the brainliest) :)

Answer:

Answer:

=2.7 g/cm³

=2700 kg/m³

Explanation:

Density is a ratio of the mass of an object to its volume.

The volume of the named block of aluminium is calculated as follows:

90mL - 75mL= 15mL

15mL = 15 cm³

The mass = 40.5 g

Therefore ρ=m/v

=40.5g/15cm³

=2.7 g/cm³

=2700 kg/m³

Answer: If a substance is the limiting reactant, then it will be completely used by the time the reaction completes because it is the reactant that reacts completely and the reaction stops after it is completely used up.

Explanation:

Limiting reagent is a reagent as it limits the formation of product and Excess reagent is the reagent which is preset in excess.

For example: if 0.75 moles of HCl and 1.5 moles of magnesium are reacted together.

[tex]Mg(s)+2HCl(aq)\rightarrow MgCl_2(aq)+H_2(g)[/tex]

According to stoichiometry:

As 2 mole of [tex]HCl[/tex] reacts with 1 mole of [tex]Mg[/tex]

0.75 moles of [tex]HCl[/tex] will react with =[tex]\frac{1}{2}\times 0.75=0.38moles[/tex] of [tex]Mg[/tex]

[tex]HCl[/tex] is a limiting reagent as it limits the formation of product and Mg is an excess reagent as (1.5-0.38)=1.12 moles of magnesium are left unreacted.

Answer:  If a substance is the limiting reactant, then it will be fully consumed by the time the reaction completes because it is the reactant that reacts completely and the reaction cannot proceed further.

Answer:

used to date rocks and other objects based on the known decay rate of radioactive isotopes.

Explanation:

Different methods of radiometric dating can be used to estimate the age of a variety of natural and even man-made materials.

Answer:

Copper ions are reduced into copper atoms.

Cu²⁺₍aq₎ + 2e⁻ →  Cu₍s₎

Explanation:

During electrolysis,  the positive H⁺ and Cu⁺ ions move to the negative cathode and negative OH⁻ and Cl⁻ ions move to the positive anode.

At cathode, copper ions are preferentially discharged due to the low electromotive force required to discharge them compared to the hydrogen ion. The copper ions gain the two electrons lost by the chloride ions when the are discharged. (2 Cl⁻₍aq₎ → Cl₂₍g₎ + 2e⁻)

Thus the half equation is as follows:

Cu²⁺₍aq₎ + 2e⁻ →  Cu₍s₎

Answer:

The correct answer is D: the reactants are generally two ionic compounds in aqueous solution.

Explanation:

A type of reaction in which two reactants participate and exchange ions with each other as the reaction proceeds. Such type of reaction is known as a double displacement reaction. In double displacement reaction, the product formed is precipitate.

Below is the pathway of the double displacement reaction:

AB + CD → AD + CB

In double displacement reaction usually, ionic compounds are involved. The bond formation between the reacting species may be ionic or covalent in nature.

Final answer:

In a double-replacement reaction, two ionic compounds in aqueous solution exchange ions to form two new products, requiring one product to be insoluble for a reaction to occur.

Explanation:

In a double-replacement reaction, the reactants are generally two ionic compounds in aqueous solution. These reactions involve the exchange of anions and cations between the reactants to form two new products. For a reaction to occur, one of the products must be insoluble in water, forming a solid precipitate, or a molecular compound such as water; if both products remain soluble, no reaction has taken place. Energy in terms of heat or light is not a characteristic feature of double-replacement reactions, unlike some other types of chemical reactions.

Examples include reactions where a precipitate, gas, or molecular compound forms, all of which signify a chemical change. The general formula for these reactions is AB + CD → AD + BC, indicating the switch between anions and cations.

Answer: the answer is C!

Heat is released during the process

Explanation:

This means that 285.8 kJ/mol is evolved when one mole of water is formed.

The term enthalpy of formation has to do with the energy that is released or absorbed when a molecule of water if formed from its constituents.

The fact that the enthalpy of formation of water is -285.8 kJ/mol implies that 285.8 kJ/mol is evolved when one mole of water is formed.

Learn more about enthalpy of formation:https://brainly.com/question/14563374?

#SPJ6

Answer:

3rd is the correct answer

(NH[tex]_4[/tex])[tex]_2[/tex]SO[tex]_4[/tex] is the chemical formula for ammonium sulfate. Therefore, the correct option is option D.

A chemical formula is a way to describe the chemical ratios of the atoms that make up a specific chemical compound or molecule in chemistry. Chemical element symbols, numbers, as well as occasionally other symbols, including such parentheses, dashes, brackets, commas, and plus (+) and minus (-) signs, are used to represent the chemical elements.

They can only include one typographic row of symbols, and they can additionally include subscripts or superscripts. A chemical formula has no words and is not the same as the chemical name. A chemical formula does not equal a complete chemical structural formula, despite the fact that it may suggest some basic chemical structures. (NH[tex]_4[/tex])[tex]_2[/tex]SO[tex]_4[/tex] is the chemical formula for ammonium sulfate.

Therefore, the correct option is option D.

To know more about chemical formula, here:

https://brainly.com/question/29031056

#SPJ7

Answer:

The correct answer is option D.

Explanation:

In modern periodic table, elements are arranged in increasing order of a their atomic numbers in 7 horizontal and 18 vertical columns.

Horizontal rows are known as periods.

In his periodic table, elements in the same periods has same number of principle quantum number or shells.

Vertical columns are known as groups:

In his periodic table, elements having similar properties lied in the same vertical columns or groups because all the elements had same number of valence electrons or outer electrons.

Answer:

Hydrogen bonding attracts water molecules to one another and slows the rate of evaporation- last choice

Answer: Option (a) is the correct answer.

Explanation:

Vapor pressure is defined as the pressure exerted by vapors or gas on the surface of a liquid.

So, the greater the intermolecular forces present between the molecules of a substance, lower the vapor pressure.

Evaporation is defined as the ability of a substance's molecules to readily convert into vapors.

In water molecules, there exists hydrogen bonding which is a strong bonding. As a result, molecules are not able to readily convert into vapors due to which no force will exert easily on the surface of water molecules.

Hence, water will have an unusually low vapor pressure.

Thus, we can conclude that water have an unusually low vapor pressure for a liquid because the oxygen-hydrogen bond in a water molecule is unusually strong, which decreases the rate of evaporation.

Answer:

Explanation:

The total energy or intrinsic energy of a system is called the enthalpy. In thermochemistry, we have two types of enthalpy changes which are:

For the freezing of water, the enthalpy change is an exothermic one. Exothermic changes are designated as negative. In this chemical change, heat is liberated to the surroundings and this leaves the environment at a much higher temperature. In freezing, the enviroment gains more heat as the material begins to cool to lower temperature.

Entropy is the degree of randomness or disorderliness of a system. When a phase change occurs from liquid to solid, freezing takes place. Such a change increases the orderliness of a system and entropy diminishes. Here, entropy is negative.

The free energy is a measure of the energy a system that does useful work. Free energy depends on enthalpy, entropy and temperature of a system. For phase changes such as freezing of water, the value of free energy change is 0.

For this process, an increases in temperature makes it non-spontaneous. Increasing temperature would alter the course of the reaction and makes it exothermic. For entropy, increasing temperature would increase entropy and therefore, the reaction would not be feasible.

Temperature would mostly affect the free energy. An increase in temperature would increase the value of entropy change and the reaction would not be spontaneous. With falling temperature value, the reaction becomes more spontaneous and favored.

Answer:

"A physicist is someone who studies or completes research into physics. There are many subsets of physics, ranging from very small particle physics to very large cosmology, or study of the universe. There are a wide number of physics courses and majors available. These courses are available at the undergraduate, graduate, and doctoral levels."

                                           "What Is a Physicist? - wiseGEEK"

Physicists study natural phenomena through experiments and observational examinations, creating theories that explain how the world works. For example, physicists studied the phenomenon of gravity and came up with a generally functioning law, the law of gravity. In addition, physicists study phenomena associated with the universe, the motion and mass of objects, electricity, and various other natural phenomena.

Answer:

In the chemical industry, lithium-based batteries are working most efficiently and replacing nickel-cadmium batteries. To study a redox reaction in a lithium battery let's take the example of Lithium Cobalt Oxide(LiCoO2).

Following is the overall reaction taking place in Lithium Cobalt Oxide battery. Reduction and oxidation takes place at Cathode and Anode respectively. that is why it is called a redox reaction.

Reaction at cathode:

Cathode: CoO2+Li+e−→ LiCoO2 (Reduction)

Reaction at Anode:

Anode: LiC6→ C6+Li++e− (Oxidation)

Overall reaction:  

LiC6 + CoO2→ C6 + LiCoO2

The practice of interlocking fingers and rubbing during hand washing is crucial for effective cleanliness. It ensures that dirt and germs from all areas of the hands, including between the fingers and under the nails, are removed.

The act of interlocking the fingers and rubbing them together while washing hands has an important role in maintaining cleanliness. This technique is crucial as it not only cleans the surfaces of the hands but it ensures that the spaces between the fingers, which can often harbor dirt and germs, also gets adequately cleaned. Similarly, the act of rubbing helps to physically dislodge dirt and microorganisms, enhancing the effectiveness of handwashing.

It's worth noting that the backs of the hands, the palms, and especially under the fingernails are areas that can house a good amount of dirt and germs. Therefore, special attention should be paid to these areas. The process of interlocking can help clean the nails and the spaces between the fingers effectively.

https://brainly.com/question/33442263

#SPJ3

Interlocking the fingers and rubbing during hand washing is key for cleaning the spaces between fingers, which helps remove germs and bacteria from hard-to-reach areas, contributing to effective hand hygiene.

The importance of interlocking the fingers and rubbing while washing hands is to ensure that the spaces between the fingers get thoroughly cleaned. This action helps to remove dirt, germs, and bacteria that might be present between fingers, which are areas that are commonly missed when washing hands. It is important to perform this action, along with washing all other parts of the hands, including the fingernails, palms, and the backs of the hands, to maintain good hygiene and prevent the spread of diseases.

Answer:

B

Explanation:

bevxjs zkbxkxbxo xkd ksbslbsi ixbxksbzo

Answer:

copper carbonate

Explanation: