Answer:
1984
Explanation:
Given the formula;
0.693/t1/2 = 2.303/t log (Ao/A)
Where;
t1/2 = half life of the radioactive isotope
t= age of the wine
Ao= initial activity of the wine
A= activity of the at time = t
0.693/12.3 = 2.303/t log (5.5/0.688)
0.693/12.3 = 2.079/t
0.056 = 2.079/t
t= 2.079/0.056
t= 37 years
The wine was produced 37 years ago which means that it was produced in the year 1984
The wine has been produced in the year 1984.
Half-life can be defined as the time required by the substance to reduce to half of its initial concentration.
The decay of wine per minute has been = 0.688/minute
The half-life of the sample has been = 12.3
The decay of freshwater has been= 5.5 decay/minute
k can be given as:
k = [tex]\rm \dfrac{0.693}{Half-life}[/tex]
k = [tex]\rm \dfrac{0.693}{12.3}[/tex]
k = 0.056 years
The time for the decay can be calculated as:
t = [tex]\rm \dfrac{2.303}{k}\;log\; \dfrac{a}{a\;-\;x}[/tex]
t = [tex]\rm \dfrac{2.303}{0.056}\;\times\;log\;\dfrac{5.5}{0.688}[/tex]
t = 37 years
The wine has been produced 37 years ago. The present year has been 2021. The year of wine production has been:
Year of wine production = 2021 - 37
Year of wine production = 1984.
The wine has been produced in the year 1984.
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Determine the number of moles of aluminum in 2.154 x 10-1 kg of Al. Group of answer choices 5816 mol 7.984 mol 6.02 X 1023 mol 4.801 mol 8.783
Answer:
Avogadro's number is 1 mol = 6.02 * 10^23 elements
It means that 1 mol of atoms is 6.02 * 10^23 atoms
1 mol of atoms = 6.02 * 10^23 atoms
From there, if you divide both sides by 1 mol of atoms, you get
1 = 6.02 * 10^23 atoms / 1 mol of atoms.
That means, that to pass from a number of moles of atoms to number of atoms you have to multipby by the conversion factor
6.02*10^23 atoms Al/ 1 mol Al
That is the second option of the list.
Explanation:
How many moles of Al are needed to react exactly with 10.00 moles of Fe2O3 according to the following
equation?
Fe2O3 + 2 Al → Al2O3 + 2Fe
A) 15.0 moles
1
B) 20.0 moles
C) 30.0 moles
D) 60.0 moles
E) 35.0 moles
Answer:
Answer is B) 20.0 moles
Explanation:
From the equation,
1 mole of Fe2O3 = 2 moles of Al
therefore 10.0 moles of Fe2O3 = 10×2
= 20.0 moles.
Carboxylic acids and alcohols react via dehydration and condensation to produce a/an _______ and water.
Question options:
amine
ether
polymer
ester
Answer:
ester
Explanation:
Carboxylic acids and alcohols react in the presence of strong acid to produce an ester and water. The two carbon chains come together, which is the condensation, and then water is generated, which is dehydration. The resulting compound is an ester.
What minimum mass of HCl in grams would you need to dissolve a 2.2 g iron bar on a
padlock?
2.8 g is the minimum mass of HCl in grams that would you need to dissolve a 2.2 g iron bar on a padlock.
What is dissolution?When a solute is dissolved in a solvent, a solution is created. Dissolution is the process through which solutes, or dissolved parts, combine to form a solution inside a solvent. In this procedure, the gas, liquid, or solid dissolves inside the original solvent and forms a solution.
In some polymer applications, dissolution is also an issue since it results in swelling, a loss of strength and stiffness, and a change in volume. Whether a chemical process is man-made or natural, dissolution is crucial. Catalysts are tested using dissolution. 2.8 g is the minimum mass of HCl in grams that would you need to dissolve a 2.2 g iron bar on a padlock.
Therefore, 2.8 g is the minimum mass of HCl in grams that would you need to dissolve a 2.2 g iron bar on a padlock.
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Answer EIGHT questions.
1(a) Whai do you mean by generation of computer? Describe brieíly
5
about third and fourth generations of computer.
B
moga dele
Answer:
Generation in computer terminology is a change in technology a computer is/was being used. Initially, the generation term was used to distinguish between varying hardware technologies. Nowadays, generation includes both hardware and software, which together make up an entire computer system.
5 generation of computer
Main electronic component: based on artificial intelligence, uses the Ultra Large-Scale Integration (ULSI) technology and parallel processing method.
ULSI – millions of transistors on a single microchip
Parallel processing method – use two or more microprocessors to run tasks simultaneously.
Language – understand natural language (human language).
Power – consume less power and generate less heat.
Speed – remarkable improvement of speed, accuracy and reliability (in comparison with the fourth generation computers).
Size – portable and small in size, and have a huge storage capacity.
Input / output device – keyboard, monitor, mouse, trackpad (or touchpad), touchscreen, pen, speech input (recognise voice / speech), light scanner, printer, etc.
Example – desktops, laptops, tablets, smartphones, etc.
3 generation of computer
Main electronic component – integrated circuits (ICs)
Memory – large magnetic core, magnetic tape / disk
Programming language – high level language (FORTRAN, BASIC, Pascal, COBOL, C, etc.)
Size – smaller, cheaper, and more efficient than second generation computers (they were called minicomputers).
Speed – improvement of speed and reliability (in comparison with the second generation computers).
Input / output devices – magnetic tape, keyboard, monitor, printer, etc.
Examples – IBM 360, IBM 370, PDP-11, UNIVAC 1108, etc.
4 generations of computer
Main electronic component – very large-scale integration (VLSI) and microprocessor.
VLSI– thousands of transistors on a single microchip.
Memory – semiconductor memory (such as RAM, ROM, etc.)
RAM (random-access memory) – a type of data storage (memory element) used in computers that temporary stores of programs and data (volatile: its contents are lost when the computer is turned off).
ROM (read-only memory) – a type of data storage used in computers that permanently stores data and programs (non-volatile: its contents are retained even when the computer is turned off).
Programming language – high level language (Python, C#, Java, JavaScript, Rust, Kotlin, etc.).
H2+O=???????????????????
Answer:
H₂O
Explanation:
Two molecules of Hydrogen and one molecules of Oxygen, when mixed, create H₂O, or water. There is no scientific name for H₂O due to it's common name. It is just refereed to as "water" or H₂O.
một chất hữu cơ có cấu tạo c2h2 cho khí br2 vào ta được hỗn hợp khí
Answer:
C2H2 + Br2 → C2H2Br2
Explanation:
What volume of water is produced when 38.5 g of ethanol reacts with oxygen at 500°C at 1.75 atm?
CH3CH2OH(g) + 3 O2(g)→ 2 CO2(g) + 3 H2O(g)
Answer:
90.99 or 91.0
Explanation:
Using the balanced equation, you convert 38.5g of ethanol to moles of water. From there, you plug the values into the Ideal Gas Equation: PV=nRT.
Answer: The volume of oxygen gas is 91.4 L.
Explanation:
The number of moles is defined as the ratio of the mass of a substance to its molar mass. The equation used is:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex] ......(1)
Given mass of ethanol = 38.5 g
Molar mass of ethanol = 46 g/mol
Plugging values in equation 1:
[tex]\text{Moles of ethanol}=\frac{38.5g}{46g/mol}=0.840 mol[/tex]
The given chemical equation follows:
[tex]CH_3CH_2OH(g)+3O_2(g)\rightarrow 2CO_2(g)+3H_2O(g)[/tex]
By stoichiometry of the reaction:
If 1 mole of ethanol produces 3 moles of water
So, 0.840 moles of ethanol will produce = [tex]\frac{3}{1}\times 0.840=2.52mol[/tex] of water
The ideal gas equation is given as:
[tex]PV=nRT[/tex] .......(2)
where
P = pressure = 1.75 atm
V = volume of oxygen gas = ?
n = number of moles= 2.52 moles
R = Gas constant = 0.0821 L.atm/mol.K
T = temperature of the tank = [tex]500^oC=[500+273]K=773K[/tex]
Putting values in equation 2, we get:
[tex]1.75 atm\times V=2.52mol\times 0.0821L.atm/mol.K\times 773K\\\\V=\frac{2.52\times 0.0821\times 773}{1.75}=91.4L[/tex]
Hence, the volume of oxygen gas is 91.4 L.
Draw a formula for Thr-Gly-Ala (T-G-A) in its predominant ionic form at pH 7.3. You may assume for the purposes of this question that the pKa values of the acidic groups of amino acid residues in the peptide are the same as in the amino acid itself.
Answer:
gggggggggg
Explanation:
gggggggg
The tripeptide formed from threonine, glycine and alanine is neutral at the pH of 7.3. The carboxylic end is negative charged by donating its proton to form the NH₃⁺ group.
What is peptide?Peptides are protein units formed from two or more amino acids bonded through peptide bonds. There are essential and non-essential amino acids. Essential amino acids have to be uptake from food and non-essential amino acids are synthesized inside the body.
Threonine is an essential amino acid with a CH₃CHOH side group. Glycine has the simplest side group hydrogen and alanine has CH₃ side chain. Both glycine and alanine are non-essential amino acids.
Each amino acids are represented with a three letter code or one letter symbol. Thus threonine is T, G for glycine and A for alanine. At a pH of 7.3 the peptide formed from these amino-acids contains a negatively charged carboxylic end.
A positively charged amino end made by protonation from the acid group make the overall charge zero. The structure of the peptide is given in the uploaded image.
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A substance which is made up of the same kind
of atom is known as?
Answer:
Element
Element : A pure substance composed of the same type of atom throughout. Compound : A substance made of two or more elements that are chemically combined in fixed amounts.
Explanation:
The elementary reaction 2H2O(g)↽−−⇀2H2(g)+O2(g) proceeds at a certain temperature until the partial pressures of H2O, H2, and O2 reach 0.0900 bar , 0.00100 bar , and 0.00350 bar respectively. What is the value of the equilibrium constant at this temperature?
Answer:
3.89 ×10^-5
Explanation:
Since they are gaseous reactants, we obtain the equilibrium constant from the given partial pressures;
p(H2O) = 0.0900 bar
p(H2) = 0.00100 bar
p(O2) = 0.00350 bar
The equation of the reaction is;2H2O(g)⇄2H2(g)+O2(g)
Kp= p(H2) . p(O2)/p(H2O)
Kp= 0.00100 × 0.00350/0.0900
Kp= 3.89 ×10^-5
2. Calculate the wavelength of the emitted photon from hydrogen for the transition from ni = 3 to nf = 2. What part of the visible spectrum is this wavelength? Visible wavelengths are: Red 700 - 620 nm, Yellow 620 - 560 nm, Green 560 - 500 nm, Blue 500 - 440 nm, and Violet 440 - 400 nm.
Answer:
The correct answer is "654.54 nm".
Explanation:
According to the question,
⇒ [tex]\frac{1}{\lambda}= Rh(\frac{1}{n1^2} -\frac{1}{n2^2} )[/tex]
By substituting the values, we get
[tex]=1.1\times 10^7(\frac{1}{4} -\frac{1}{9} )[/tex]
[tex]=1.1\times 10^7(\frac{9-4}{36} )[/tex]
[tex]=1.1\times 10^7(\frac{5}{36} )[/tex]
[tex]=654.54\ nm[/tex]
Thus the above is the right solution.
Explain the working principle of a clinical thermometer
Answer:
A clinical thermometer is a thermometer used to measure human body temperature. Most made in the 20th century are mercury-in-glass thermometers. They are accurate and sensitive, having a narrow place where the mercury level rises very fast. A kink in the tube stops the mercury level from falling on its own.
6) Hydrogen gas can be generated from the reaction between aluminum metal and hydrochloric acid:
2 Al(s) + 6 HCl(aq) + 2 AICI3, (aq) + 3 H2(g)
a. Suppose that 3.00 grams of Al are mixed with excess acid. If the hydrogen gas produced is directly collected
into a 850 mL glass flask at 24.0 °C, what is the pressure inside the flask (in atm)?
b. This hydrogen gas is then completely transferred from the flask to a balloon. To what volume (in L) will the
balloon inflate under STP conditions?
c. Suppose the balloon is released and rises up to an altitude where the temperature is 11.2 °C and the pressure is
438 mm Hg. What is the new volume of the balloon (in L)?
Stoichiometry refers to the relationship between the moles of reactants and products.
This question must be solved using both stoichiometry and the gas laws
The reaction equation is;
2 Al(s) + 6 HCl(aq) --------> 2 AICI3, (aq) + 3 H2(g)
Using stoichiometryNumber of moles of Al = 3g/27g/mol = 0.11 moles
According to the reaction equation;
2 moles of Al yields 3 moles of H2
0.11 moles of Al yields 0.11 * 3/2 = 0.165 moles
Using the gas lawsFrom the ideal gas equation;
PV=nRT
P = ?
n= 0.165 moles
V = 0.85 L
T = 297 K
R = 0.082 atmLK-1mol-1
P= nRT/V
P = 0.165 * 0.082 * 297/0.85
P= 4.73 atm
Under STP conditions;P1 = 4.73 atm
T1 = 297 K
V1 = 0.85 L
P2 = 1 atm
T2 =273 K
V2 =?
From the general gas equation;P1V1/T1 = P2V2/T2
P1V1T2 = P2V2T1
V2 = P1V1T2/P2T1
V2 = 4.73 * 0.85 * 273/1 * 297
V2 = 3.69 L
P1 = 760 mmHg
T1 = 273 K
V1 = 3.69
P2 = 438 mm Hg
T2 = 284.2 K
V2 =?
P1V1/T1 = P2V2/T2
P1V1T2 = P2V2T1
V2 = P1V1T2/P2T1
V2 = 760 * 3.69 * 284.2/438 *273
V2 = 797010.48/119574
V2= 6.67 L
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Critique this statement: Electrons can exist in any position
outside of the nucleus.
Answer:
However, there has to be 2 electrons on the first shell, and 8 on the others.
Explanation:
Hope this helps :)
How many moles of Cl− are in 5.76 mg of FeCl3?
Answer:
0.0061650760770388 mole
What is the biggest cause of change in Earth's systems?
A. Heat
B. Motion
C. Friction
D. Plate tectonics
Answer:
heat
Explanation:
because it's the cause of change
Answer:
heat
Explanation:
because it is a natural factor that causes the change in Earth's system
equal volumes 50.0 ml of 0.54897 m solution of HCL and 0.9573 M NaOH solution have an initial temperature of 18.5 degrees Celsius react in a coffee cup calorimeter the resulted Solutions records a temperature of 22.9 degrees Celsius since the solutions are mostly water the solution are assumed to have a density of 1.0 g per ml and a specific heat of 4.184 joules per gram degree celsius the heat capacity of the Colorimeter is 1.0 x 10 to power 1 joules per degrees Celsius calculate the heat and gained or released by the solution at a constant pressure in J
Answer:
Explanation:
ok
Read the following statement:
Energy cannot be created or destroyed.
Does the statement describe a scientific law? (3 points)
a
No, because it universally applies to all objects
b
No, because it is not true in all circumstances
c
Yes, because it universally applies to all objects
d
Yes, because it is not true in all circumstances
Answer:
C. yes, because it is universally applies to all objects
Choose the most correct answer: The endothermic (∆H > 0) reaction:
a) Cannot occur at all temperature.
b) Can occur with the positive ∆S at high temperature.
c) Can occur with the negative ∆S at low temperature.
d) Cannot occur with the positive ∆S at high temperature.
Answer:
B
Explanation:
In order to create spontaneity, an endothermic process has to occur along with positive entropy and high temperature
What is the oxidation state for bh3
Answer:
As hydrogen is more electronegative than boron, in BH3 the oxidation number of hydrogen should be taken as -1. (E. N. of B = 2.0 & E. N. of H = 2.1)
Suppose, oxidation number of B is x.
So, we can write, x + 3*(-1) = 0
=> x = +3
Therefore, oxidation num
Explanation:
As hydrogen is more electronegative than boron, in BH3 the oxidation number of hydrogen should be taken as -1. (E. N. of B = 2.0 & E. N. of H = 2.1)
Suppose, oxidation number of B is x.
So, we can write, x + 3*(-1) = 0
=> x = +3
Therefore, oxidation num
Dylan has a coworker who is always showing up late and then not finishing his work on time . It's frustrating the other members of the team . What can he do that might help the situation ? a ) Complain about the coworker to other team members b ) Ask his coworker if he understands his job responsibilities c ) Tell his boss that the coworker is slacking off d ) Complete his coworker's work for him
Lewis Structures are used to describe the covalent bonding in molecules and ions. Draw a Lewis structure for NO3- and answer the following questions based on your drawing.
1. For the central nitrogen atom:
The number of lone pairs = ________
The number of single bonds=_______
The number of double bonds= ______
2. The central nitrogen atom :
Answer:
The lewis structure for NO₃⁻ is shown in the attachment below
For the central nitrogen atom:
The number of lone pairs = 0
The number of single bonds = 2
The number of double bonds= 1
Explanation:
The lewis structure for NO₃⁻ is shown in the attachment below.
From the Lewis structure
For the central nitrogen atom:
The number of lone pairs = 0
The number of single bonds = 2
The number of double bonds= 1
Amphiphilic molecule: ___________
a. have both oxidizing and reducing groups.
b. are micelles.
c. have chromophores in two different wavelength regions.
d. have both acidic and basic groups.
e. have both hydrophilic and hydrophobic groups.
Is pre ap chemistry hard in high school?
If you don't practice enough it's obviously going to be hard but if you practice enough it's going to be a piece of cake so don't think if it's going to be hard or not just think it's going to be worth the try at the very end
Explain why you get a basic solution when you dissolve NaF in water.
Answer:
The fluoride ion is capable of reacting, to a small extent, with water, accepting a proton. The fluoride ion is acting as a weak Brønsted-Lowry base. The hydroxide ion that is produced as a result of the above reaction makes the solution slightly basic.
So
we get a basic solution when you dissolve NaF in water.
Na is a alkaline earth metal
Metallic compound dissolved in water acts as base
Also there is another reason
Na F is ioniC
Fluorine is known as having highest electron affinity in world
It can accept a line pair of OH-
So it's Bronsted Lowry base .
It can also acts as Arrhenius baseHence its basic
Forcus on the yellow highlighted texts, your help is appreciated.
[tex]{ \sf{ \red{no \: pranks}}}[/tex]
Answer:
Transition temperature is the temperature at which a substance changes from one state to another.
Allotropy is the existence of an element in many forms.
Consider the reaction: A(aq) + 2B (aq) === C (aq). Initially 1.00 mol A and 1.80 mol B
were placed in a 5.00-liter container. The mole of B at equilibrium was determined to
be 1.00 mol. Calculate K value.
0.060
5.1
25
17
Ugh
Answer:
17
Explanation:
Step 1: Calculate the needed concentrations
[A]i = 1.00 mol/5.00 L = 0.200 M
[B]i = 1.80 mol/5.00 L = 0.360 M
[B]e = 1.00 mol/5.00 L = 0.200 M
Step 2: Make an ICE chart
A(aq) + 2 B(aq) ⇄ C(aq)
I 0.200 0.360 0
C -x -2x +x
E 0.200-x 0.360-2x x
Then,
[B]e = 0.360-2x = 0.200
x = 0.0800
The concentrations at equilibrium are:
[A]e = 0.200-0.0800 = 0.120 M
[B]e = 0.200 M
[C]e = 0.0800 M
Step 3: Calculate the concentration equilibrium constant (K)
K = [C] / [A] × [B]²
K = 0.0800 / 0.120 × 0.200² = 16.6 ≈ 17
Each 5-ml teaspoon of Extra Strength Maalox Plus contains 450 mg of magnesium hydroxide and 500 mg of aluminum hydroxide. How many moles of hydronium ions H3O are neutralized by 1 teaspoon of antacid product?
Answer:
0.0347 moles of hydronium ions
Explanation:
The equation of the neutralization reaction between hydroxide and hydronium ions is given below:
H₃O+ (aq) + OH- (aq) ----> 2 H₂O (l)
From the equation above, 1 mole of hydroxide ions will neutralize one mole hydronium ions.
The moles of hydroxide ions present in 1 teaspoon or 5 mL of antacid product is calculated as follows:
Number of moles = mass / molar mass
Molar mass of Magnesium hydroxide, Mg(OH)₂ = 58 g/mol
Molar mass of aluminium hydroxide, Al(OH)₃ = 78 g/mol
Mass of magnesium hydroxide = 450 g = 0.45 g
Mass of aluminium hydroxide = 500 mg = 0.5 g
Moles of magnesium hydroxide = (0.45/58) moles
Moles of aluminium hydroxide = (0.5/78) moles
Equation of the ionization of magnesium hydroxide and aluminium hydroxide is given below:
Mg(OH)₂ (aq) ----> Mg²+ (aq) + 2 OH- (aq)
Al(OH)₃ (aq) ---> Al³+ (aq) + 3 OH- (aq)
Number of moles of hydroxide ions present in (0.45/58) moles of magnesium hydroxide = 2 × (0.45/58) moles = 0.0155 moles
Number of moles of hydroxide ions present in (0.5/78) moles of aluminium hydroxide = 3 × (0.5/78) moles = 0.0192 moles
Total moles of hydroxide ions = 0.0155 + 0.0192 = 0.0347 moles hydroxide ions
Therefore, 0.0347 moles of hydroxide ions will neutralize 0.0347 moles of hydronium ions.
Manganese-55 has _____neutrons.
55 Mn
25
A. 55
B. 30
C. 25
QUESTION:- Manganese-55 has _____neutrons.
OPTIONS :-
A. 55
B. 30
C. 25
ANSWER:- NUMBER OF NEUTRONS IS EQUAL TO THE DIFFERENCE BETWEEN THE MASS IF THE ATOM AND ATOMIC NUMBER
SO DIFFERENCE IS EQUAL TO :- 55-25 = 30 NEUTRONS.
SO THERE IS 30 NEUTRONS IN SINGLE ATOM OF THE MANGANESE-55 ATOM.
Answer:
the mass of an atom is the sum of proton and neutron which are both concentrated in nocleus of an atom. from the question the mass is given as 55 and the proton is 25.
