Answer:
The top left number of the symbol of an atom is the sum of the protons and neutrons in the atom known as atomic mass number, while the bottom left number of the symbol of an atom is the number of protons in the atom known as atomic number.
Explanation:
An atom of an element is composed of other subatomic particles; the electron, proton and neutron. The number of protons present in an atom of an element is equal to the number of electrons present in the atom of that element and is known as the atomic number of the element. The number of neutrons present in the atom summed together with the proton number gives the atomic mass number of an atom of the element.
Elements are represented with symbols. In writing the symbols of elements, the atomic number and the atomic mass of an atom of the element is usually written along with the symbol. The top left number of the symbol of an atom is the sum of the protons and neutrons in the atom, while the bottom left number of the symbol of an atom is the number of protons in the atom.
For example, the element sodium has an atomic number of 11 and a mass number of 23. In symbols, it is written as follows: ²³₁₁Na
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Question 10 of 12- POS
GR8 Sci U03 USA FY21 Question: 1-10
Hannah added a silvery white metal to a beaker of cold water and noticed that gas bubbles were given off and a different substance formed. When she repeated the activity with hot water she noticed the gas bubbles were
released much more rapidly. Which statement best explains why the reaction occurred faster in hot water?
M
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.
What are phytoplankton and what percentage of oxygen do they produce? (ASAP)
Answer:
They are plants also known as plankton and they produce about 80-85% of the world's oxygen.
Explanation:
PLS HELP 35 POINTS I WILL GIVE BRAINEST
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
Draw the correct structure(s) for (2R,3S)‑2,3‑dibromobutane. Show stereochemistry clearly. To ensure proper grading, explicitly draw all four groups, including wedge/dash bonds, around a chirality center. Indicate whether the compound(s):_____.a. could exist in an optically active form.b. could exist in optically active form.b. cannot exist in optically active form.c. cannot be determined.
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.
Match Term Definition
Pure substance A) Liquid homogeneous mixture in which the solute is distributed evenly within the solvent
Heterogeneous B) Mixture that has its different components mixed evenly within the substance
Homogeneous C) Mixture that has its different components mixed unevenly within the substance
Solution D) Consists of a single element or type of compound
Answer:
b
Explanation:
this should help
ammonia is______a base
Answer:
Ammonia is moderately a base
How much water must be added to 424 mL of 0.189 M HCl to produce a 0.140 M solution?
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
0.1400 mole of sucrose, C12H22O11, contains ________ moles of C.
can you show me the formula and the correct format
Answer:
it has 12 carbon atoms and 22 hydrogen atoms and 11 oxygen atoms
Explanation:
At the Sparta Fault in Greece, the hanging wall is below the footwall. This type of fault is called a .
Answer:
1 a
Explanation:
an electric current causes water to be transformed into hydrogen and oxygen gasses a physical change or a chemical change
What is the total pressure of mixture in which H2 and CO exerted 31mmHg and 510mmHg respectively
Answer:
Ans: 541 mmHg
Explanation:
given:
H2 = 31mmHg
CO= 510mmHg
get the sum
31+510=541
How are changes of state different from chemical change?
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:
Convert the speed of light, 3.0 x 10^8 m/s, into mi/hr. (1610 m = 1 mi). Could you please explain step by step thank you!
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].
A rigid 3.80 L sealed vessel contains 0.650 mol Ne, 0.321 mol Kr, and 0.190 mol Xe. Find the density of the mixture in g/L.
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
what causes convection currents in a gas or liquid?
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.
Convert 85km/hr to cm/s(factor label conversion)
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
PLEASE HURRY WILL GIVE BRAINLEST IF ANSWERED CORRECTLY
which separation method would be most successful in separating the components of a homogeneous mixture
screening
evaporation
centrifugation
magnetic separation
Answer:
Evaporation is a technique used to separate out homogeneous mixtures where there is one or more dissolved salts.
Explanation:
Hope this helps :)
A gas sample in a balloon contains 4.0 moles of gas at a particular pressure, volume and temperature. If your balloon springs a leak and the volume decreases to 1/2 of the original amount before you can plug the leak, how many moles of gas have you lost (temperature and pressure remain the same)?
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.
Determine the density of CO2 gas at STP
Answer:
the density of CO2 gas at STP is 1.96 g/l.
how is black oxide converted into red oxide
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
Provide an example of a Food Chain.
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 ^_^
Cells pump definition
Answer:
Pumps also called transporters, are transmembrane proteins that actively move ions and/or solutes against a concentration or electrochemical gradient across biological membranes.
Suppose you have 300.0 mL of a 0.450 M sodium hydroxide solution.
How many moles of sodium hydroxide are in the solution?
Answer:
135 moles
Explanation:
300*0.45
= 135
PLS GIVE BRAINLIEST
3/2 moles
Explanation: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
Which statement best describes why a chemical property change is different from a physical change?
A. A chemical change results in a different state of matter; and a physical change results in a new substance being formed.
B. A chemical change results in a new substance being formed; whereas, a physical change will result in a different state of matter.
C. A chemical change is used by scientists to create new substances, and a physical change happens naturally.
D. A chemical change is used to identify characteristics of a substance, and a physical change identifies the behavior of a substance when in a reaction.
Answer:
B
Explanation:
a chemical change is making a new substance and physical change with a result in a different state of matter:)
8
Which of the pictures demonstrates a state of matter WITHOUT a fixed shape or fixed
volume?
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.
Liquids and solids are known to have fixed shape and volume. Liquids are know for their ability to flow. Figure LSolids are rigid bodies. It is the figure JIodine 131, cesium 137, and strontium 90 are all considered isotopes. What are isotopes?
Answer:
Isotopes are variants of an element, where the number of neutrons is different but its number of protons stay the same.
Explanation:
If the number of protons had changed then it would just be a different element.
Electron number changing simply adds charge to the atom, and doesn't change it or anything.
PLS GIVE BRAINLIEST
Answer:
Isotopes are one of two or more forms of the same chemical element.
Explanation:
Different isotopes of an element have the same number of protons in the nucleus, giving them the same atomic number,but a different number of neutrons giving each element isotope of a different atomic weight.
Explain your thoughts on whether or not using solely IR is a good method to make positive IDs of chemicals.
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.
MULTIPLE CHOICE: For a combustion system, incorrect statement is?
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.
What are the starting substances (molecules) in a chemical equation called?
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.
Suppose you need to prepare 250.0 mL of a pH=3.60 buffer that has a total buffer concentration of formic acid + formate of 0.030 M. How many moles of formic acid will you need? The pKa of formic acid is 3.75.
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
[tex]4.39*10^{-3}[/tex] moles of formic acid will be needed
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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