Which of the following shows the abbreviation for an SI unit of density?

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:

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:

K

Explanation:

The picture that demonstrates a state of matter without a fixed shape or fixed volume is picture K.

Gases are one of the three states of matter without a fixed shape and volume. They simply take up the shape of their containers and are free to move all about.

Answer:

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

Answer:

B

Explanation:

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

Answer:

[tex]v=6.7\times 10^9\ mi/hr[/tex]

Explanation:

Given that,

The speed of light is 3×10⁸ m/s

We need to convert it into mi/hr.

Since, 1 mile = 1610 m

1 hour = 3600 s

So,

[tex]v=3\times 10^8\ \dfrac{m}{s}\\\\=3\times 10^8\ \dfrac{\dfrac{1}{1610}\ \text{miles}}{\dfrac{1}{3600}\ s}\\\\=6.7\times 10^9\ mi/hr[/tex]

So, the required speed of light is [tex]6.7\times 10^9\ mi/hr[/tex].

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:

2.21m

Explanation:

Molality, m, is defined as the ratio between moles of solute (The substance that is in less amount, sodium sulfide) and kilograms of solvent (Water, in this case).

Thus, we need to convert mass of sodium sulfide to moles using its molar mass and grams of water to kilograms:

Moles Na2S (Molar mass: 78.0452g/mol):

37.5g * (1mol / 78.0452g) = 0.48 moles Na2S

Kilograms water:

217g * (1kg / 1000g) = 0.217kg

Molality:

0.48 moles Na2S / 0.217kg =

Answer:

2.21

Explanation:

Answer:

The usual way of converting black oxide to red oxide involves treating the black oxide with sulphuric acid and then roasting the intermediate product thus formed. lt is known that the amount of acid can be considerably less than the stoichiometric amount needed to convert all the black oxide to a sulphate.

Hope it helps :9

Answer:

2.7g/cm³

Aluminum

Explanation:

Given parameters:

Mass of the cube  = 72.9g

Unknown:

Density of the cube = ?

Solution:

To solve this problem, we need to find the density of the cube. The mass is given and the dimensions of the solid figure.

Now;

       Density is the mass per unit volume of a substance

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

Volume of the cube  = L³  = 3³   = 27cm³

So;

     Density  = [tex]\frac{72.9}{27}[/tex]   = 2.7g/cm³

The body is aluminum because it has a density of  2.7g/cm³

Answer:

135 moles

Explanation:

300*0.45

= 135

PLS GIVE BRAINLIEST

3/2 moles

We are given:

Molarity of the solution = 0.450 M

Volume of the Solution = 300 mL OR 0.3 L

Solving for the number of moles:

We know that the formula for molarity:

M = nV          (where n is the number of moles and V is the volume in Liters)

replacing the variables

0.450 = n * (0.3)

n = 0.450 / 0.3

n = 3/2 moles

Therefore, we have 3/2 moles of Na(OH) in the give solution

Answer:

1 a

Explanation:

Answer:

b. cannot exist in optically active form

Explanation:

Stereochemistry is a branch of chemistry that involves the spatial arrangement of the atoms of molecules and studies how this affects the physical and chemical properties of such species.

The correct structure for (2R,3S)‑2,3‑dibromobutane can be seen in the image attached below. Since the compound is a meso compound due to the plane of symmetry. Thus, the compound is achiral. i.e. Compounds that are superimposable on its mirror image. The plane of symmetry is vertical inclined at 90°(i.e. perpendicular) to the page thus goes via the middle of the molecule.

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.

Answer:

I THINK it's D, I could be incorrect, however.

Explanation:

C3H8O, as it is flammable, and thus I wouldn't imagine it being a product of combustion. I could be incorrect, so take my answer with a grain of salt.

Answer: Diamond is the name ^-^

A food chain only follows just one path as animals find food. eg: A hawk eats a snake, which has eaten a frog, which has eaten a grasshopper, which has eaten grass. A food web shows the many different paths plants and animals are connected. eg: A hawk might also eat a mouse, a squirrel, a frog or some other animal.

Hope this helps ^_^

Answer:

The number of moles of formic acid needed is 4.5x10⁻³ moles.

Explanation:

We can find the moles of formic acid using the Henderson-Hasselbalch equation:

[tex] pH = pKa + log(\frac{[CHOO^{-}]}{[CHOOH]}) [/tex]

We know:

pH = 3.60

pKa = 3.75                    

By solving the above equation for [CHOO⁻]/[CHOOH] we have:

[tex] \frac{[CHOO^{-}]}{[CHOOH]} = 10^{(pH - pKa)} = 10^{(3.60 - 3.75)} = 0.71 [/tex]

[tex] [CHOO^{-}] = 0.71[CHOOH] [/tex]  (1)

Now, we have:

[tex] [CHOOH] + [CHOO^{-}] = 0.03 M [/tex]   (2)

By entering equation (1) into (2) we have:

[tex] [CHOOH] + 0.71[CHOOH] = 0.03 M [/tex]

[tex] [CHOOH] = 0.018 M [/tex]

Hence, the concentration of formate is:

[tex] [CHOO^{-}] = (0.03 - 0.018)M = 0.012 M [/tex]

Finally, the number of moles of formic acid is:

[tex] n_{CHOOH} = [CHOOH]*V = 0.018 \frac{mol}{L}*0.250 L = 4.5 \cdot 10^{-3} moles [/tex]

Therefore, 4.5x10⁻³ moles of formic acid are needed.

I hope it helps you!  

We have that for the Question "How many moles of formic acid will you need?"

It can be said that

From the question we are told

to prepare 250.0 mL of a pH=3.60, total buffer concentration of formic acid + formate of 0.030 M, The pKa of formic acid is 3.75.

Let [tex]1+COO4 = X, 1+COON = (0.03-X)[/tex]

[tex]pH = pKa + log\frac{1+COON}{1+COO4}\\\\3.6 = 3.75 +log\frac{0.03-X}{X}\\\\log\frac{0.03-X}{X} = 3.6 - 3.75\\\\\frac{0.03-X}{X} = 0.708\\\\X = 0.0175M[/tex]

Therefore,

[tex]moles of formic acid = 0.0175*0.25mole\\\\= 4.39*10^{-3}mole[/tex]

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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:

No, IR should not soely be used to identify molecules

Explanation:

IR is a method that identifies the functional groups in a molecule by deducing the frequency of stretching and vibration of bonds. Each peculiar type of bond has a frequency for the vibration of each bond represented on the IR spectrum.

However, one method is never enough to identify a compound. A combination of methods must always be used to clear up ambiguities arising from overlapping IR frequencies. Also,  interpretation of the nuanced peaks of the fingerprint region in IR spectra is quite challenging and only gives a fair idea of the functional groups present in the compound.

Therefore other methods such as NMR, UV-VISIBLE etc should also be involved in the identification of compounds.

Answer:

17.09g/L

Explanation:

Density = total mass of elements/ volume

We need to find the mass of each mixture constituents using their molar mass:

mole = mass/molar mass

For Neon (Ne) which contains 0.650mol;

0.650 = mass/20.18

mass = 0.650 × 20.18

mass = 13.12g

For Krypton (Kr) which contains 0.321mol;

0.321 = mass/83.79

mass = 0.321 × 83.79

mass = 26.89g

For Xenon (Xe) which contains 0.190mol;

0.190 = mass/131.3

mass = 0.190 × 131.3

mass = 24.95g

Total mass = 13.12g + 26.89g + 24.95g = 64.96g

Density = total mass / volume

Density = 64.96g / 3.80L

Density of the mixture = 17.09g/L

Answer:

23.61m/s

Explanation:

Km/hr is a unit of expressing the speed of a body. Speed is the rate of change of distance with time. Also, the same unit is applicable for expressing the velocity of a body. But to find the velocity, we must emphasize the direction of motion of the body.

Given parameter:

        85km/hr to cm/s

 Note:

         1000m  =1km

          3600s  = 1hr

 So;

      85 x

Cancelling out km and hr;

  =    85 x 0.278m/s

= 23.61m/s

Answer:

Ans: 541 mmHg

Explanation:

given:

H2 = 31mmHg

CO= 510mmHg

get the sum

31+510=541

Answer:

Ammonia is moderately a base

Answer:

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

Explanation:

Answer:

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

Explanation:

Answer:

Convection currents are caused by a temperature difference in gases and liquids. As one area becomes warmer than another the molecules have more energy and start vibrating more vigorously thus spreading out and becoming less dense. This means that the less dense parts will become more buoyant causing them to rise.

Explanation:

Answer:

Convection currents are caused by a temperature difference in gases and liquids.  

Explanation:

As one area becomes warmer than another the molecules have more energy and start vibrating more vigorously thus spreading out and becoming less dense. This means that the less dense parts will become more buoyant causing them to rise.

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:

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