A graduated cylinder initially has 32.5 mL of water in it. After a 75.0 g piece of lead (Pb) is added to the graduated cylinder, the water level rises to the 39.1 mL mark. What is the the volume of the piece of lead.

Answer:

Observational study

Explanation:

An investigation of what happened over the years to the people who were exposed to radiation during the 1986 Chernobyl nuclear disaster would be termed an observational study because it will require observing subjects and finding out if there is a kind of correlating factor in the subjects that could indicate the level of exposure to the nuclear radiation.

There are basically two types of research studies:

1. Observational studies

2. Experimental studies

Observational studies involve just the observation of subjects and trying to find out some correlation factors. This kind of study could be prospective when it deals with what could happen in the future based on certain factors or retrospective when it considers what has already happened. An observational study can be cross-sectional, case-only, case-control, or cohort study.

Experimental studies are also referred to as randomized or controlled trial studies. Here, subjects are grouped and each group receives a different treatment in order to isolate the effect of a particular factor or variable relating to the treatment.

Answer:

100Jkg/°C

Explanation:

Given parameters:

Mass of metal  = 2kg

Amount of heat energy  = 1600J

Initial temperature  = 5°C

Final temperature = 13°C

Unknown:

Specific heat capacity of the metal  = ?

Solution:

Specific heat capacity of a body is the amount of heat needed to raise the temperature of unit mass of a body by 1°C.

  H  = m x C x (T₂ - T₁ )

H is the amount of heat

m is the mass

C is the unknown specific heat capacity

T is the temperature

     Insert the parameters and solve;

  1600 = 2 x C x (13 - 5)

   1600  = 16C

        C = 100Jkg/°C

Answer:

Explanation:

When volume of gas is V , pressure is P and temperature is T , if n be number of moles of gas

PV / RT = n , R is universal gas constant .

When volume becomes .5 V , pressure P and temperature T

number of moles = Px .5 V / RT = .5 PV / RT = .5 n

Number of moles of gas becomes half .

so 4 moles becomes  2 moles

No of moles lost = 4 - 2 = 2 moles.

The correct answer is Hot water increases the collision rate of molecules, causing the reaction to occur faster.

Explanation:

Temperature is directly related to the kinetic energy or movement of molecules in a substance. In this context, a higher temperature leads to more kinetic energy or more collision between molecules. At the same time, a chemical reaction involves molecules of two or more substances colliding and creating bonds to form new substances. This implies an increase in temperature means molecules colliding faster, new substances forming in a shorter time, and therefore a faster chemical reaction. According to this, the first answer is correct.

Answer:

The temperature is on the y-axis and the time is on the x-axis.

Explanation:

Which statement describes how phase changes can be diagrammed as a substance is heated? (D is the answer)

The phase is on the y-axis and the temperature is on the x-axis.

The temperature is on the y-axis and the phase is on the x-axis.

The time is on the y-axis and the temperature is on the x-axis.

The temperature is on the y-axis and the time is on the x-axis.

Which statement describes the appearance of a temperature-vs.-time graph? (C is the answer)

A horizontal line shows that the temperature increases at a constant rate over time.

A vertical line shows that the temperature decreases at a constant rate over time.

Horizontal lines where the temperature is constant during phase changes connect upward-sloping lines where the temperature increases.

Horizontal lines where the temperature increases are connected by upward-sloping lines where the temperature is constant for each phase.

Answer:

the density of CO2 gas at STP is 1.96 g/l.

Answer:

A chemical reaction is the process in which atoms present in the starting substances rearrange to give new chemical combinations present in the substances formed by the reaction. These starting substances of a chemical reaction are called the reactants, and the new substances that result are called the products.

Answer:

Just count all the different elements like what elemets are in there and you have to identify the number of elemenst

Explanation:

for example H20 and a chemical for example thats two so you identofy which elelments are in there doesnt matter if thered multiple of it all its asking is what id the number of elemts there meaning like one or 2 mayne six different elements

Answer:

Ammonia is moderately a base

Question:

How are changes of state different from chemical change?

Answer:

Physical changes alter only the size, shape, form or matter state of a material. Water boiling, melting ice, tearing paper, freezing water and crushing a can are all examples of physical changes.

On the other hand, chemical changes are a bit different. In a chemical change, a new substance is formed.

Answer:

Chemical change happens when a substance changes they molecular structure, it often involves change in color (rusting iron), transfer of energy (copper smelting), or gas bubbling.

Changes of state is a physical change. An example is ice, it melts to create water. Water then can be freezed back to ice. Water is still H2O in both states（solid/liquid) Dissovling is another example. You can dissolve salt in water and can separate it by evaporating water and leaving the salt behind.

Explanation:

Answer:

Volume of water added = 148.4 mL

Explanation:

Given data:

Initial volume = 424 mL

Initial molarity = 0.189 M

Final molarity = 0.140 M

Volume of water added = ?

Solution:

Formula:

M₁V₁  =   M₂V₂

0.189 M×424 mL = 0.140 M×V₂

V₂ = 0.189 M×424 mL /0.140 M

V₂ = 80.136 M.mL / 0.140 M

V₂ = 572.4 mL

Final volume of solution is  572.4 mL.

Volume of water added = Final volume - initial volume

Volume of water added = 572.4 mL - 424 mL

Volume of water added = 148.4 mL

Answer:

Explanation:

1) Pure substance: Water (found at home)

Appearance: It is homogeneous since it is a single substance that appears as liquid. Homogeneous is when the components of a substance are in a single phase

Separating technique: It's component cannot be separated by physical means

Boiling point: Water boils at 100 °C

Melting point: Water melts/freezes at 0°C

2) Pure substance: Table salt (found at home)

Appearance: It is also homogeneous as it is a single substance that is solid. Separating technique: It's component cannot be separated by physical means

Boiling point: Water boils at 1,465 °C

Melting point: Water melts/freezes at 801 °C

3) Pure substance: Butter (found at home and grocery store)

Appearance: It is homogeneous even though it contains different components

Separating technique: It's component can be separated by physical means since butter is an emulsion of fat in water. The 15% water content can be evaporated/distilled out at 100 °C

Boiling point: Butter starts boiling at about 110-120 °C

Melting point: It melts at about 37 °C

4) Pure substance: Candle (wax) (found at home and grocery store)

Appearance: It is homogeneous

Separating technique: It's component cannot be separated by physical means

Boiling point: It starts boiling around 370 °C

Melting point: It melts at about 37 °C

5) Pure substance: table sugar/sucrose (found at home, grocery stores and in supermarkets)

Appearance: It is homogeneous

Separating technique: It's component cannot be separated by physical means

Boiling point: It starts boiling around 697 °C

Melting point: It melts at about 186 °C

A pure substance is an homogeneous material, having a composition, and

properties that are consistent through out the material.

The chemical properties of a pure substance are defined, such as the

products of its reaction can be predictable.

A chemical is pure when it consist of a single type of particle such as an

element, a molecule or a compound.

The five pure substances are presented as follows;

[tex]\displaystyle\begin{tabular}{|l|l|l|l|l|}\underline{Pure \ Substances}&\underline{Appearance}&\underline{Separaing Tech}&\underline{Boiling \ Point}&\underline{Melting \ point}\\1. Diamond&Translucent \ solid&Inseparable&3550^{\circ}&4830^{\circ}\\2. Table \ salt&White\ crystals&Insepble&801^{\circ}&1413^{\circ}\\3. Water&Tran parent \ liquid&Insepble&0^{\circ}&100^{\circ}\\4. Sugar&Whilte \ crystals&Heating&Decomposes&186^{\circ}\\5. Gold&Yellowish \ metal&Inseparable& 2700^{\circ}&1064^{\circ}\end{array}[/tex]

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Answer:

m = 0.00659 kg = 6.59 g

Explanation:

From Faraday's Law of Electrolysis, we know that:

m = ZQ

where,

m = mass of silver deposited = ?

Q = charge supplied = (1.65 A-hr)(3600 s/1 hr) = 5940 C

Z = electrochemical equivalent of silver = 1.18 x 10⁻⁶ kg/C

Therefore,

m = (1.11 x 10⁻⁶ kg/C)(5940 C)

m = 0.00659 kg = 6.59 g

The mass of silver that would be deposited by a battery is 6.65 grams

The precipitation of Ag requires the removal of one electron. The reduction process for silver electrode at the cathode is as follows:

[tex]\mathbf{Ag^+ + e^- \to Ag(s)}[/tex]

∴

In one mole of an electron, the charge carried = 96500 C

Recall that:

The atomic mass of silver (Ag) = 108 g

∴

The mass of silver that would be deposited in a 5940 C can be computed as:

[tex]\mathbf{=5940\ C \times \dfrac{108 \ g }{96500 \ C}}[/tex]

= 6.65 grams

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Answer:

it has 12 carbon atoms and 22 hydrogen atoms and 11 oxygen atoms

Explanation:

Answer:

B

Explanation:

a chemical change is making a new substance and physical change with a result in a different state of matter:)

Answer:

C

Explanation:

Al=Aluminum

Mg=Magnesium

Answer:

Evaporation is a technique used to separate out homogeneous mixtures where there is one or more dissolved salts.

Explanation:

Hope this helps :)

Answer:

b

Explanation:

this should help

Answer:

oxygen, silicon, iron, calcium, sodium

Explanation:

these are all found in space rocks known as meteorites. hope this helps :)

The ions are able to move freely from one place to another. So that they conduct electricity. But the molecular solutions does not electricity.

The molecular solution is composed of molecules and consists of non - metallic atoms. These atoms are held together by the covalent bonds. The flow of charged particles is responsible for the conduction of electricity. If there is no flow of electrons or ions then there will be no electricity.

In the molecular solutions, the molecules present are not dissociated into respective ions. Since the molecules are not converted into the charged particles no electricity is produced.

A molecular solution is regarded as a non-electrolyte which does not contain ions. But electrolytes are dissociated into ions and thereby conducts electricity. So all electrolytes are good conductors of electricity.

Thus molecular solution does not contain ions.

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Answer:

Pumps also called transporters, are transmembrane proteins that actively move ions and/or solutes against a concentration or electrochemical gradient across biological membranes.

There is a golden role of solubility, polar solute dissolve in polar solvent and non polar solute dissolve in non polar solvent. Therefore, the correct option is option B that is Salt and water.

Solutions are a homogeneous mixture of two or more substances. A solution is a homogeneous mixture of solvent and solute molecules. Solvent is a substance that is in large amount in solution. solute is the substance which is in small amount in a solution. There are two types of mixture that is homogeneous and heterogeneous. Solution is a homogeneous solution.

Salt and water because salt is transparent and will dissolve into the water among given solute, salt NaCl is a polar solute which will dissolve in polar solvent that is water.

Therefore, the correct option is option B that is Salt and water.

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Answer:

He won 32 games.

Explanation:

Another way of expressing 75% is 75/100.

To calculate how many games the baseball pitcher won, we multiply the total of games played (43, in this case) by the percent won:

43 * 75/100 = 32.25 ≅ 32

So the baseball pitcher won 32 games.

Answer:

Antoine Lavoisier

1) Law of Conservation of Mass

French chemist, Antoine Lavoisier in 1789, studied this law. This law states that “In all physical and chemical changes, the total mass of the reactants is equal to that of the products” or “Mass can neither be created nor destroyed.”

Answer:

They are plants also known as plankton and they produce about 80-85% of the world's oxygen.

Explanation:

Answer:

The Universe is constantly expanding and as it expands the stars and objects in space move farther apart, just like the points on the balloon when air is blown into it. Density and distribution of "stars" as the balloon expands because when volume increases the density will increase.

Hope this Helps

Answer:

These are called isotopes. They have the same number of protons (and electrons), but different numbers of neutrons. Different isotopes of the same element have different masses. Mass is the word for how much substance (or matter) something has.

Answer:

[tex]r_{NOCl}=9.28x10^{-2}M[/tex]

Explanation:

Hello!

In this case, given the balanced chemical reaction:

[tex]2 NO(g) + Cl_2(g) \rightarrow 2 NOCl(g)[/tex]

Since there is 1:2 mole ratio between chlorine and NOCl, based on the rate proportions, we can write:

[tex]\frac{1}{-1}r_{Cl_2} =\frac{1}{2}r_{NOCl}[/tex]

It means that for the formation of NOCl, we obtain:

[tex]r_{NOCl}=\frac{2}{-1}r_{Cl_2} \\\\r_{NOCl}=\frac{2}{-1}(-4.64x10^{-2}M)\\\\r_{NOCl}=9.28x10^{-2}M[/tex]

Notice that chlorine is disappearing, which means its rate is negate.

Best regards!