In an atomic model that includes a nucleus, positive charge is
a
concentrated at multiple sites in an atom.
b
concentrated in the center of an atom.
c
spread evenly throughout an atom.
d
located in the space outside the nucleus.
Dominic needs some bleach to clean up a spill. He finds a bottle of cleaning solution, but there is no label on it. What should he do
Answer:
He should ask an adult if they know what the solution is. if they dont, put it back and find a different cleaning solution to use
Trends in the periodic table indicate that the element with the greatest ionization energy is in which of the following periods and groups?
a
Period 2, Group 1
b
Period 7, Group 2
c
Period 6, Group 17
d
Period 1, Group 18
Answer:
D Period 1, Group 18
Explanation:
it's helium
it's top right corner of the periodic table
Which drawing is structural model of C3H8?
Answer:
option B is the correct answer
10:38 Fri 9 Jul
ES
GCSE Science - Chemistry
2 of 15
Name the indicator that is red in acid and turns green when the solution becomes neutral.
|
Answer.
Universal indicator
Explanation.
Universal indicator has many different colour changes, from red for strongly acidic solutions to dark purple for strongly alkaline solutions. In the middle, neutral pH 7 is indicated by green.
Which expression is equal to f(x) · g(x)?
Answer:
C. x⁴ + 6·x³ - 12·x - 72
Explanation:
The given functions are;
[tex]f(x) =\sqrt{x^2 + 12 \cdot x + 36}[/tex]
g(x) = x³ -12
We have that [tex]f(x) =\sqrt{x^2 + 12 \cdot x + 36}[/tex] = [tex]f(x) =\sqrt{(x + 6)^2}[/tex] = (x + 6)
Therefore;
f(x)·g(x) = [tex]\sqrt{x^2 + 12 \cdot x + 36}[/tex] × (x³ - 12) = (x + 6) × (x³ - 12)
(x + 6) × (x³ - 12) = x⁴ - 12·x + 6·x³ - 72 = x⁴ + 6·x³ - 12·x - 72
∴ f(x)·g(x) = [tex]\sqrt{x^2 + 12 \cdot x + 36}[/tex] × (x³ - 12) = x⁴ + 6·x³ - 12·x - 72
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.
ASAP!!!!!!!!!
Answer:
Molecular mass, M = 58.20 g/mol.
Explanation:
Given the following data;
Density = 2.41 g/literTemperature = 25°CPressure = 770 mmHgGas constant, R = 0.0821 L atm.mol-1K-1Conversion:
760 mmHg = 1 atm
770 mmHg = 770/760 = 1.0131 atm
Temperature = 25°C = 273 + 25 = 298 K
To find the molecular mass, we would use the ideal gas law equation (density version);
PM = dRT
Where;
P is the pressure.M is the molecular mass.d is the density of a substance.R is the ideal gas constant.T is the temperature.Making M the subject of formula, we have;
[tex] M = \frac {dRT}{P} [/tex]
Substituting into the formula, we have;
[tex] M = \frac {2.41 * 0.0821 * 298}{1.0131} [/tex]
[tex] M = \frac {58.9626}{1.0131} [/tex]
Molecular mass, M = 58.20 g/mol.
cuantas moléculas de oxigeno se producen por la descomposición de 28.5 g de H2O2 (masa molecular = 34.0g/mol) de acuerdo a la ecuación
2H2O2(l) → 2H2O(l)+O2(g)
The question is as follows: How many oxygen molecules are produced by the decomposition of 28.5 g of H2O2 (molecular mass = 34.0g / mol) according to the equation
2H2O2 (l) → 2H2O (l) + O2 (g)
Answer: There are [tex]2.52 \times 10^{23}[/tex] molecules are produced by the decomposition of 28.5 g of [tex]H_{2}O_{2}[/tex] according to the equation [tex]2H_{2}O(l) \rightarrow 2H_{2}O(l) + O_{2}(g)[/tex].
Explanation:
Given: Mass of [tex]H_{2}O_{2}[/tex] = 28.5 g
As moles is the mass of a substance divided by its molar mass. Hence, moles of [tex]H_{2}O_{2}[/tex] is calculated as follow.
[tex]Moles = \frac{mass}{molarmass}\\= \frac{28.5 g}{34.0 g/mol}\\= 0.838 mol[/tex]
According to the given equation, 2 moles of [tex]H_{2}O_{2}[/tex] gives 1 mole of [tex]O_{2}[/tex]. So, moles of [tex]O_{2}[/tex] produced by 0.838 moles of [tex]H_{2}O_{2}[/tex] will be calculated as follows.
[tex]Moles of O_{2} = \frac{0.838 mol}{2}\\= 0.419 mol[/tex]
This means that moles of [tex]O_{2}[/tex] produced is 0.419 mol.
As per the mole concept, 1 mole of every substance has [tex]6.022 \times 10^{23}[/tex] molecules.
So, molecules of [tex]O_{2}[/tex] present in 0.419 mole are as follows.
[tex]0.419 \times 6.022 \times 10^{23}\\= 2.52 \times 10^{23}[/tex]
Thus, we can conclude that there are [tex]2.52 \times 10^{23}[/tex] molecules are produced by the decomposition of 28.5 g of [tex]H_{2}O_{2}[/tex] according to the equation [tex]2H_{2}O(l) \rightarrow 2H_{2}O(l) + O_{2}(g)[/tex].
draw the flow chart of production of silk from silk moth
please help....
no links or get reported
Too lazy to draw sorry lol.
#CarryOnLearning
I actually just looked it up via image search.
just copy by hand either of the flow charts.
if you can, use colors to fill. makes it more interesting to look at
and define a circle (or rather a few points on it) to draw it neatly. the defined points can later be transformed into the arrows.
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.
True or false
If an atom is charged positive, it contains more protons than electrons.
Answer:
TRUE
Explanation: because it is positively charged and protons are positive ions
A student is asked to separate two liquids. Liquid A boils at 100°C
and liquid B boils at 65 °C. The student sets up a fractional distillation
experiment, and after a few minutes a clear liquid is collected from the
condenser. Explain which of the two liquids will be collected first.
Answer:
liquid B
Explanation:
because B has a lower bp it needs less time and energy to turn into vapour and is collected into the condenser first
Why is it essential for a calorimetry to be an insulated (closed) system?
A. The heat exchange must originate from only the reaction (system).
B. Thermal insulation minimizes energy loses to the atmosphere.
C. A and B
D. None of the Above
Answer:
B.Thermal insulation minimizes energy loses to the atmosphere.
Explanation:
It is important because it helps to stop hit from transferring from the calorimeter to the environment. This would help to have an accurate measurement of the heat that was used in the chemical process. The greatest cause of error that happens in calorimetry is when heat is lost to the environment. To reduce this, you insulate the calorimeter and add a cover.
A 4.369 g sample of metal is placed in a flask. Water is added to the flask and the total volume in the flask is read to be 126.4 ml. The mass of the water, flask, and metal is 268.5 g. If the mass of the flask is 139.3 g and the density of water is 1.000 g/mL, the density of the solid is ________ g/cm3.
Answer:
Density of the solid=[tex]2.78 g/cm^3[/tex]
Explanation:
We are given that
Mass of sample of metal=4.369 g
Volume in the flask, V=126.4 ml
Mass of water, flask, and metal=268.5 g
Mass of flask=139.3 g
Density of water=1.000 g/mL
We have to find the density of the solid.
Mass of water=268.5-4.369-139.3=124.831 g
Volume of water=[tex]\frac{Mass\;of\;water}{density\;of\;water}[/tex]
Volume of water=[tex]\frac{124.831}{1}=124.831 mL[/tex]
Volume of solid=126.4 ml-124.831 mL
=1.569mL
Now,
Density of the solid=[tex]\frac{mass\;of\;solid}{volume\;of\;solid}[/tex]
=[tex]\frac{4.369}{1.569}[/tex]
[tex]=2.78g/mL[/tex]
1mL=1 cubic cm
Therefore,
Density of the solid=[tex]2.78 g/cm^3[/tex]
In the hydrogenation of double bonds, a catalyst is needed. In the third step, the reactants react to form the product. This step is known as
Answer:
reaction
Explanation:
A reaction is defined as a process where the chemical transformation takes place from one form to some other form. Here, two different chemical substances are reacted together to form some other completely different product.
A hydrogenation process is a chemical process where between the molecular hydrogen and some another element or a compound. This process is usually carried out in the presence of catalyst mainly nickel, platinum or palladium.
Thus, in hydrogenation of a double bond, the catalyst is used to speed up the reaction. The first step in this process is adsorption process, the second step is the diffusion process, the third step is the reaction process and the last step is the desorption process.
I am having trouble converting :(
Answer:
For the first question, to determine the total number of molecules of nitrogen dioxide, first make use of the molar mass of the nonpolar compound and then use that to find the total number of moles and then subsequently after make use of the ratio for the Avogadro's number to determine the total number of molecules of this compound.
For the final question, do the inverse, where we make use of the molecules of the compound and then use Avogadro's number to determine the moles of the compound and then use the same molar mass of the compound to determine the grams of the Nitrogen Dioxide.
Determine the excluded volume per mole and the volume actually occupied by a mole for a gas consisting of molecules with radius 167 pm. [Note: To obtain the volume in liters, we must express the radius in decimeters (dm).] Enter your answers in scientific notation.
Answer:
Explanation:
Volume of one mole of a gas = 22.4 litre.
No of molecules in one mole of gas = 6.02 x 10²³ .
Volume of one molecule = 4/3 π R³
= 4/3 x 3.14 x ( 167 x 10⁻¹² m )³
= 19.5 x 10⁶ x 10⁻³⁶ m³
=19.5 x 10⁻³⁰ m³
= 19.5 x 10⁻³⁰ x 10³ litre .
= 19.5 x 10⁻²⁷ litre .
So volume occupied by molecules in one mole of gas
= 19.5 x 10⁻²⁷ x 6.02 x 10²³ litre
117.4 x 10⁻⁴ litre
= .01174 litre.
Excluded volume
= ( 22.4 - .01174 ) litre .
= 22.388 litre.
what are neutral salts
Answer:
Salts that produce acidic solutions are acid salts. Neutral salts are those salts that are neither acidic nor basic. Zwitterions contain an anionic and a cationic centre in the same molecule, but are not considered to be salts. Examples of zwitterions include amino acids, many metabolites, peptides, and proteins.
Explanation:
what is average velocity with formula?
Answer:
total displacement \time
Explanation:
Select the correct text in the passage.
Explanation:
Oceans can influence weather and climate. For example, cities located near large water bodies like oceans tend not to have extreme climates
Which of the following elements has three valence electrons? (2 points)
Li
C
Al
Mg
Answer:
Al
Explanation:
It has 3.
A student is asked to seperate two liquids. Liquid A boils at 100°c and liquid B boils at 65°c. The student sets up a fractional distillation experiment, and after a few minutes a clear liquid is collected from the condenser. Explain which of the two liquids will be collected first. ( 2 marks).
Answer:
B
Explanation:
because B has a lower bp it needs less time and energy to turn into vapour and is collected into the condenser first
Balance equation for. _Mg + _H3(PO4) --_Mg3(PO4)2+ _H2
Na3N decomposes to form sodium and nitrogen gas at STP. If 13.7 L of nitrogen is produced
how many moles of Na3N was used? (22.4 L = 1 mole of any gas)
2Na3N --> 6Na + N2
Answer: 1.224 moles of [tex]Na_3N[/tex] were used.
Explanation:
We are given:
Volume of nitrogen gas produced = 13.7 L
At STP conditions:
22.4 L of volume is occupied by 1 mole of a gas
Applying unitary method:
13.7 L of nitrogen gas will be occupied by = [tex]\frac{1mol}{22.4L}\times 13.7L=0.612mol[/tex]
For the given chemical reaction:
[tex]2Na_3N\rightarrow 6Na+N_2[/tex]
By Stoichiometry of the reaction:
1 mole of nitrogen gas is produced by 2 mole of [tex]Na_3N[/tex]
So, 0.612 moles of nitrogen gas will be produced from = [tex]\frac{2}{1}\times 0.612=1.224mol[/tex] of [tex]Na_3N[/tex]
Hence, 1.224 moles of [tex]Na_3N[/tex] were used.
True or false, If an atom is charged negative, it contains more electrons than protons.
Answer:
True
Explanation:
An atom would carry more protons if positively charged, an equal amount of both protons and electrons if neutral, and more electrons if charged negative.
Which compound is a glycol?
CH3―CH2―CH2―CHO
CH3—CH2—O—CH2—CH3
CH3—CH2—CH2—CH2OH
HOH2C―CH2―CH2―CH2OH
Answer:
CH3—CH2—O—CH2—CH3 is the compound of glycol.
Answer:
HOH2C―CH2―CH2―CH2OH is glycol
Explanation:
Fe-54 = 5.845%
Fe-56 = 91.754%
Fe-58 = 2.119%
Calculate the average atomic mass/given their percent abundance
Answer:
[tex]\boxed {\boxed {\sf 55.76756 \ amu}}[/tex]
Explanation:
The average atomic mass is the sum of the product of the given masses and their abundances. We have to complete two steps for each isotope, then add all the products together.
Fe-54
Convert the percent abundance to a decimal by dividing by 100.
5.845/100= 0.05845Multiply the abundance as a decimal by the mass number. This is the number after the element in the isotope symbol (54 amu).
0.005845 * 54=3.1563 amuFe-56
Convert the percent to a decimal.
91.754/100=0.91754Multiply the decimal by the mass number (56 amu).
0.91754 * 56= 51.38224 amuFe-58
Convert the percent to a decimal.
2.119/100=0.02119Multiply by the mass number (58 amu).
0.02119 * 58 = 1.22902 amuAverage Atomic Mass
Add all the products together to find the average atomic mass.
3.1563 amu + 51.38224 amu + 1.22902 amu =55.76756 amuThe average atomic mass given the percent abundance is 55.7656 atomic mass units.
Zn-64 = 48.63%
Zn-66 = 27.90%
Zn-67 = 4.10%
Zn-68 = 18.75%
Zn-70 = .62%
Calculate the atomic mass/given their percent abundance
Answer:
A = 65.46 u
Explanation:
Given that,
The composition of zinc is as follows :
Zn-64 = 48.63%
Zn-66 = 27.90%
Zn-67 = 4.10%
Zn-68 = 18.75%
Zn-70 = .62%
We need to find the average atomic mass of the given element. It can be solved as follows :
[tex]A=\dfrac{48.63\times 64+27.90\times 66+4.1\times 67+18.75\times 68+0.62\times 70}{100}\\A=65.46\ u[/tex]
So, the average atomic mass of zinc is 65.46 u.
Select the correct answer.
Which missing item would complete this beta decay reaction?
ОА. 0,-1В
OB. 0,0y
OC. 4,2He
OD. 0,1n
Reset
Answer:
Option A. ⁰₋₁β
Explanation:
Let the unknown be ʸₓA
Thus, the equation given becomes:
⁹⁸₄₃Tc —> ⁹⁸₄₄Ru + ʸₓA
Next, we shall determine the value of x, y and A in order to obtain the answer to the question. This can be obtained as follow:
43 = 44 + x
Collect like terms
43 – 44 =
–1 = x
x = –1
98 = 98 + y
Collect like terms
98 – 98 = y
0 = y
y = 0
ʸₓA => ⁰₋₁A => ⁰₋₁β
Thus, the complete equation is
⁹⁸₄₃Tc —> ⁹⁸₄₄Ru + ⁰₋₁β
The missing item is ⁰₋₁β
an experiment was carried out and H2SO4 was collected resulting in a 92.0% yield. What mass of H2SO4 was collected from the experiment?
Answer:
The mass of H2SO4 collected is 92.0g assuming the theoretical yield of H2SO4 is 100g
Explanation:
Assuming the theoretical yield of the sulfuric acid, H2SO4, is 100g.
To solve this question we must use the equation of percent yield:
Percent yield = Actual yield / Theoretical yield * 100
Where percent yield = 92.0%, actual yield is the mass of H2SO4 produced and theoretical yield is 100g, the mass we are assuming
Replacing:
92.0% = Actual yield / 100g * 100
92.0g = Actual Yield
The mass of H2SO4 collected is 92.0g assuming the theoretical yield of H2SO4 is 100g