Answer:
B
Explanation:
because protons have a +1 charge and electrons have a -1 charge, so if an atom is neutral it must have the same amount of protons and neutrons
1) The percentage of oxygen in dry air is _______
A. 0.1
B. 1.0
C. 21
D. 79
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
A. Oxygen
B. Carbon dioxide
C. Ammonia
D. Nitrogen
Answer:
1) The percentage of oxygen in dry air is _______
C. 21
2) The composition of the Earth’s earliest atmosphere was different to that of the present atmosphere. Which of these gases was present in large amounts in the Earth’s earliest atmosphere?
B. CARBON DIOXIDE
Hope it helps
have a nice day
Answer: The percentage of oxygen in dry air is . 21
Explanation: Ammonia gases was present in large amounts in the easth7s earliest atmosphere
Hope it will help you
You are a chemist working in your laboratory. In your storage closet you have a
cabinet that holds only samples of pure elements, no compounds. While looking for a
sample of lithium (LI), you notice that the label on one bottle has worn off. The room is
at normal temperature. The contents of the bottle are liquid and do not look metallic.
What element should you relabel the bottle as?
A.Helium
B.Bromine
C.Arsenic
D.Chlorine
Hematite is a naturally occurring mineral and a common form of iron ore. The following statements describe physical and chemical changes occurring to hematite. Which statement describes a chemical change?
When the hematite particles rearrange to form a new substance", this statement describes chemical change.
What is chemical change ?A chemical change is a change of materials into another, new materials with different properties and one or more than one new substances are formed.
As a chemical changes is usually a change where a substance undergoes a chemical change and forms a new substance; which cannot be easily reversed into reactants by any simple physical methods.
In this example the hematite ore forms a new substance by an irreversible chemical change.
Hence, "The hematite particles rearrange to form a new substance", this statement describes chemical change.
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5.34x10 to the 27th power molecules of sulfur hexafluoride to moles of sulfur hexafluoride
Answer:
8.87 × 10³ moles.
Explanation:
To convert number of molecules of sulfur hexafluoride (SF6) to moles (n), we divide by Avogadro's number (6.02 × 10²³)
That is; n = N ÷ nA
According to the question, 5.34 x 10^27 molecules of SF6 was given in this question. Hence, the number of moles it contains is given as:
n = 5.34 x 10^27 ÷ 6.02 × 10²³
n = 5.34/6.02 × 10^ (27-23)
n = 0.887 × 10⁴
n = 8.87 × 10³ moles.
HELP ASAP!! PLEASE !!
Answer:
8,3, 7,7
Explanation:
Question 2: Heat (5 points)
A. Describe the following heat equations, and identify the indicated variables.
i. Q = mcΔT; identify c. (1 point)
ii. Q = mLvapor; identify Lvapor. (1 point)
iii. Q = mLfusion; identify Lfusion. (1 point)
Answer:
(i) specific heat
(ii) latent heat of vaporization
(iii) latent heat of fusion
Explanation:
i. Q = mcΔT; identify c.
Here, Q is heat, m is the mass, c is the specific heat and ΔT is the change in temperature.
The amount of heat required to raise the temperature of substance of mass 1 kg by 1 degree C is known as the specific heat.
ii. Q = mLvapor; identify Lvapor
Here, Q is the heat, m is the mass and L is the latent heat of vaporization.
The amount of heat required to convert the 1 kg liquid into 1 kg vapor at constant temperature.
iii. Q = mLfusion; identify Lfusion
Here, Q is the heat, m is the mass and L is the latent heat of fusion.
Here, Q is the heat, m is the mass and L is the latent heat of vaporization.
The amount of heat required to convert the 1 kg solid into 1 kg liquid at constant temperature.
(i) c is the molar heat capacity of the substance.
(ii) Lvapor is the latent heat of evaporation of the substance
(iii) Lfusion is the latent heat of fusion of the substance
All the 3 equations fall under Calorimetry.
In all the equation Q is the amount of heat required.
(i) First equation represents the amount of heat required to raise the temperature of a substance of mass m.
Q = mcΔT
here c is the molar heat capacity of the substance and ΔT is the chnage in temperature.
(ii) Second equation represents the amount of heat required to convert a substance of mass m from liquid phase to vapour phase.
Q = mLvapor
here Lvapor is the latent heat of evaporation of the substance
during evaporation no change in temperature occurs.
(iii) Third equation represents the amount of heat required to convert a substance of mass m from solid phase to liquid phase.
Q = mLfusion
here Lfusion is the latent heat of fusion or melting of the substance
during fusion no change in temperature occurs.
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If charge on only one object is tripled, determine the new force between them:
Answer:
+3·F
Explanation:
The number of objects in the given system = 2 objects
The charge on each object are; q₁ = -Q, q₂ = -Q
The force acting between the objects = +F
The distance between the objects = 2·d
The formula for the force acting between two charged particles is given as follows;
[tex]F=K \times \dfrac{q_{1} \times q_{2}}{r^{2}}[/tex]
Therefore, we get;
[tex]F=K \times \dfrac{-Q \times -Q}{(2\cdot d)^{2}} = K \times \dfrac{Q^2}{4 \cdot d^2}[/tex]
By tripling the charge, q₁, on the first object, we get;
q₂ = 3 × (-Q)
[tex]F_2=K \times \dfrac{-3 \cdot Q \times -Q}{(2\cdot d)^{2}} = K \times \dfrac{3 \cdot Q^2}{4 \cdot d^2} = 3 \times +F = +3\cdot F[/tex]
Therefore, the new force between them, F₂ = +3·F
As a pure element the oxidation number of zinc is ________, but in compounds such as ZnCO3 its oxidation number is ________. Group of answer choices
Answer:
0, +2
Explanation:
As a pure element, any element or simple compound has an oxidation number of 0. This makes it a lot easier, and can be applied for almost any element or compound that uses one atom, like F2, O3, Zn, Fe, etc. However, in compounds, Zinc's oxidation number tends to be +2, and this is just a rule that I memorized when I learned this topic. Please let me know if you still need help and I hope you understood!
As a pure element, the oxidation number of zinc is zero, but in compounds such as [tex]ZnCO_3\\[/tex] its oxidation number is +2.
What is the oxidation number?Oxidation number also called oxidation state, is the total number of electrons that an atom either gains or loses in order to form a chemical bond with another atom.
As a pure element, any element or simple compound has an oxidation number of 0. This makes it a lot easier and can be applied for almost any element or compound that uses one atom, like [tex]F_2[/tex], [tex]O_3[/tex], Zn, Fe, etc.
However, in compounds, Zinc's oxidation number tends to be +2.
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Place the steps of the action potential in order.
- a brief reversal of membrane potential that travels along the axon
- mechanism that restores the resting membrane voltage and intracellular ionic concentrations
- reversal of the resting potential due to an influx of sodium ions
- period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability
Answer:
-Reversal of the resting potential due to influx of sodium ions
-Mechanism that restores the resting membrane voltage and intracellular ionic concentrations
-Period during which potassium ions are diffusing out of the neuron because of a change in membrane permeability
-A brief reversal of membrane potential that travels along the axon
Explanation:
An action potential is a situation where the membrane potential is briefly reversed from -70mV to +30 mV
There are three steps of the moving action potential, including;
1) The depolarization step, where the membrane resting potential is reversed by the rush of sodium ions into a neuron
2) The repolarization, due to the closing of the voltage-gated sodium channels and the opening of the potassium channels, which is a mechanism that restores the membrane's resting voltage and the ionic concentration in the cell
3) Hyperpolarization, where due to some open potassium channels, there is an increased potassium permeability, and excessive efflux of potassium ions take place, which results in a dip in the membrane potential
4) The above three phases describe the phase of the action potential which is the brief reversal of membrane potential that travels along the axon
Find the mass in grams of 15.00 moles of AICI:
Answer:
937.5g
Explanation:
No of moles = mass ÷ molar mass
According to this question, there are 15moles of the compound; AlCl
Molar mass of AlCl = 27 + 35.5
= 62.5g/mol
Using n = m/M.M
15 = m/62.5
m = 15 × 62.5
m = 937.5g
Glycerin, , is a nonvolatile liquid. What is the vapor pressure of a solution made by adding glycerin to at
Complete question is;
Glycerin, C3H8O3, is a nonvolatile liquid. What is the vapor pressure of a solution made by adding 164 g glycerin to 338 mL H2O at 39.8°C?
The vapor pressure of pure water at 39.8°C is 54.74 torr and its density is 0.0992 g/cm³
Answer:
28 torr
Explanation:
Let's first find the number of moles of water in 338 mL.
Molar mass of water = 18 g/mole
Formula for number of moles = mass/molar mass.
Mass = density × volume = 0.0992 × 338 = 33.5296 g
Thus;
Number of moles = 33.5296/18 = 1.863 moles.
Let's use the same procedure to find the Number of moles of glycerine.
Molar mass of glycerine from online values = 92.1 g/mol
Thus;
n_glycerine = (mass)/92.1
We have mass and density as 164 g and 0.0992 g/cm³ respectively.
n_glycerine = 164/92.1
n_glycerine = 1.78
Total moles of solution = 1.863 + 1.78 = 3.643 moles
We are told that The vapor pressure of pure water at 39.8°C is 54.74 torr
Thus, since water dominates, then vapour pressure of solution = (1.863/3.643) × 54.74 ≈ 28 torr
Stoichiometry - Chemistry
Answer:
C
Explanation:
in the option C when we rearrange it then it will he C3H6O2
Answer:
yes its C
Explanation:
correct me if iam wrong
How many cm3 in a L?
Un medicamento corresponde a una disolución de "nafazolina" (sustancia activa) en agua purificada, en una concentración de 12% V/V. - EXPLICA cuánto soluto hay por cada 100mL del medicamento.
Answer:
12 mL
Explanation:
Según la pregunta;
V / V% concentración del fármaco = 12%
volumen de la solución = 100 ml
De;
V / V% = volumen de fármaco / volumen de solución
volumen de fármaco = V / V% × volumen de solución
volumen de fármaco = 12/100 × 100
= 12 mL
.
Unlike a theory, a scientific law describes an observed pattern without attempting to _____ it.
explain
prove
test
verify
The mass of a boy is 60 kg. Calculate his weight if the value of g is 9.8 ms2
Answer:
Weight = mass × gravitational
Weight = 60 kg × 9.8 ms²
= 588 N
Explanation:
hope it helps
Weight of the boy = Mass of the boy × g
= 60 × 9.8
= 588kgm/s²
= 588N
If 14.7 cm3 of alcohol is present in 70 cm 3 of its aqueous solution, the percentage by volume of alcohol will be?
Answer: The percentage by volume of alcohol will be 21%.
Explanation:
Given: Volume of solute = 14.7 [tex]cm^{3}[/tex]
Volume of solvent = 70 [tex]cm^{3}[/tex]
Formula used to calculate percentage by volume is as follows.
[tex]Percentage volume = \frac{volume of solute}{volume of solvent} \times 100[/tex]
Substitute the values into above formula as follows.
[tex]Percentage volume = \frac{volume of solute}{volume of solvent} \times 100\\= \frac{14.7 cm^{3}}{70 cm^{3}} \times 100\\= 21 percent[/tex]
Thus, we can conclude that the percentage by volume of alcohol will be 21%.
solve this question please! it have 3 options which one of them is correct option
Answer:
I think option two (2) is the correct answer
Help me and I'll make u Brainliest eat and follow u
19. place moth balls in the closet and observe after several days.
20. whenever wax or a candle burns it turns from solid to liquid but again at room temperature it turns to solid
21. evaporation, condensation, precipitation
22. it produces new substances
23. vinegar Bubbles when baking soda is added
24. steam
Heat is most closely related to which kind of energy?
O nuclear
electrical
thermal
chemical
Answer:
C thermal
Explanation:
every action produces an equal and opposite -- ---------- when one object exterts a force on another object,the second object pushes back with the same amount of---------
someone knows the answer
explain why the boiling point of aluminum is higher than sodium
Explanation:
this is the reason why aluminium's boiling point is higher than that of sodium. sodium forms Na+ ions, therefore 1 electron is lost from each sodium atom, whereas aluminium forms Al3+ ions, so 3 electrons are lost for each Aluminum atom. The number of delocalised electrons therefore increases from sodium to aluminium, and charge density of the ions increases as the ionic charge increases and size decreases.
A gas has density 2.41 g/liter at 25°C and 770 mm Hg. Calculate it's molecular mass (R = 0.0821 L atm.mol-1K-1
Answer:
Explanation:
Given : Density - 2.41 g/liter
Temperature - 25° C
Pressure : 770 mm Hg
R = 0.0821 L atm mol-¹K-¹
Find : Molecular mass of gas
Solution : Ideal gas equation with respect to density will be : PM = dRT. In the formula, P is pressure, M is molecular mass, d is density, R is gas constant and T is temperature.
Keeping the values in equation-
Pressure : 770 mm Hg = 1 atm
Temperature : 273 + 25 = 298 K
M = dRT/P
M = (2.41*0.0821*298)/1
M = 58.96 gram/mol
Thus, the molecular mass of gas is 58.96 gram/mol.
How would an increased level of acetyl-CoA be expected to affect the pyruvate dehydrogenase reaction
Answer:
The pyruvate dehydrogenase kinase enzyme activity would increase, resulting in an inhibition of pyruvate dehydrogenase activity. ... An in vitro study shows that isocitrate dehydrogenase is activated in the citrate cycle.
Explanation:
Which of the following statements regarding the movement of electrons during cellular respiration is true?
A. Electrons tend to move away from O2.
B. O2 is reduced when it accepts electrons and forms water.
C. The electrons release large amounts of energy each time they are transferred from one molecule to another.
D. O2 is eventually oxidized by the electrons to form water.
Answer:
B. O2 is reduced when it accepts electrons and forms water.
Explanation:
During cellular respiration water is formed when oxygen receives electrons and picks up protons at the conclusion of the electron transport chain. The electron transport chain will stop functioning if there isn't enough oxygen to receive electrons (for example, because a person isn't breathing in enough oxygen), and ATP will no longer be created by chemiosmosis. Cells can't carry out the reactions they need to function if they don't even have enough ATP, and they may perish after a long period of time.
Help me guys ☹️please
Answer:
Coriolis Effect
Explanation:
The Coriolis Effect is caused by Earths rotation. We can not only see this affecting how winds move, but also where storms form and the movement of oceans currents.
thank you so much for putting all the answers in there
Answer:
[tex]\huge\color{cyan}{\colorbox{magenta}{Answer}}[/tex]
thank you
In the SI system of units, the mole is one of seven base units. It is frequently used in chemical calculations. However, a mole of something is just a particular quantity of it. It is not a unit of measure in the way that meters, seconds, and kilograms are. Calculations performed with the number of moles of a substance could also be performed with the number of particles of a substance. Based on this information, do you think that the mole should be considered a base unit in the SI system? Explain why or why not.
The international system of units is known as SI and is a metric system. Mostly used as a system of measurement. It is used in science, technology, and nearly in every part of the country. The system includes coherent units known as derived units.
A mole is not a base unit or any property of the units. It can be used for physical and chemical comparison and hence the mole of substance can be performed with the number of particles of the substance.Hence the option B is correct.
Learn more about the frequently used in chemical calculations.
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 Help ASAP only right answers only no spam don’t answer if you don’t know
i know the answer is a theory
Select the correct answer.
0.22 M
HCI
Unknown
LiOH
What is the concentration of the base (LIOH) in this titration?
1.0 ml
0.5 ml
Initial
burette
reading
Final
burette
reading
13.3 ml
18.5 ml
OA
0.16 M
ОВ.
0.15 M
OC. 0.22 M
OD
18 M
O E
0.5 M
Daset
Answer:
=0.15M
Explanation:
To get the moles of the unknown LiOH, calculate the number of moles of HCl in 12.3mL.
Using the stoichiometric coefficient, mole ratio 1:1.
This means that the number of moles is the same. This number of moles is contained in 18mL. Then Calculate the molarity (concentration) which is in 1000mL
See the explanation from the image I have shared with you for calculations.
