Answer:
3
Explanation:
Applying,
[tex]2^{n'}[/tex] = R/R'............... Equation 1
Where n' = number of halflives that have passed, R = Original atom of the substance, R' = atom of the substance left after decay.
From the question,
Given: R = 40 atoms, R' = 5 atoms
Substitute these values into equation 1
[tex]2^{n'}[/tex] = 40/5
[tex]2^{n'}[/tex] = 8
[tex]2^{n'}[/tex] = 2³
Equation the base,
n' = 3
Please hurry this is due tomorrow morning
A student is studying the ways different elements are similar to one another. Diagrams of
atoms from four different elements are shown below.
Which two atoms are of elements in the same group in the periodic table?
F Atom 1 and Atom 2
G Atom 1 and Atom 4
H Atom 2 and Atom 3
J Atom 3 and Atom 4
Plz Help I have One more time To retake and I can't fail it..
Answer:
A
Explanation:
Hydrogen bonds are intermolecular forces of interaction that exist between molecules of a substance in which hydrogen is bonded to a highly electronegative atom. Hydrogen bonds are strong intermolecular forces and account for high melting and boiling points of small molecules such as water. They stem from dipole-dipole interaction between molecules of a substance.
Metallic bonds are bond forces which exist in a metal. Metal cations are held together by a sea of electrons via electrostatic interaction.
The ionic bond is formed by transfer of electrons from one atom to another leading to the formation of an ion pair held together by electrostatic attraction.
Metallic bonds and hydrogen bonds are much weaker than ionic bonds. Ionic compounds are known to have high melting and boiling points.
how to prepare hydrogen gas
can u plz solve it n send the answer
1. Cl2 + H2O → HOCl + HCl
2. Tooth decay starts when when the pH of the mouth is lower than 5.5. Tooth enamel is made up of calcium phosphate and it is one of the hardest substances of the body. But it is corroded when the pH is less than 5.5. The bacteria of our mouth produce acids by degradation of sugar and food particles remaining in our mouth after eating food.
3. Fluorine salts are added in toothpaste to protect our teeth from tooth decay. Fluorine salts are mildly basic, so they neutrelise the acid in our mouth that leads to tooth decay.
4. Tincture of iodine is iodine, pottasium iodide and sodium iodide dissolved in ethanol. Iodine acts in an antiseptic manner by destroying microbial proteins and DNA.
5. Tincture of iodine is clear and reddish brown liquid.
hello, please help!! asap!
Answer:
I think your correct but I'm not so sure
What is the change in enthalpy of the first reaction below, given the enthalpies of the other two reactions?
Here's the reactions:
There was a formatting issue with the specific chemistry symbols, there all correct in the picture below
2C(s) + O2(g) → 2CO(g)
C(s) + O2(g) → CO2(g) ∆H0= -394 KJ/mol
CO(s) + 1/2 O2(g) → CO2(g) ∆H0= -283 KJ/mol
There was a formatting issue with the specific chemistry symbols, there all correct in the picture below
Answer:
∆H0 = -222kJ/mol
Explanation:
Using Hess's law, we can find the ΔH of a reaction from the sum of another related reactions as follows:
Using the reactions:
(1) C(s) + O2(g) → CO2(g) ∆H0= -394 KJ/mol
(2) CO(s) + 1/2 O2(g) → CO2(g) ∆H0= -283 KJ/mol
Twice (1):
2C(s) + 2O2(g) → 2CO2(g) ∆H0= 2*-394 KJ/mol = -788kJ/mol
The inverse reaction of (2):
-(2) CO2(g) → CO(g) + 1/2 O2(g) ∆H0= 283 KJ/mol
Twice this reaction:
2*-(2) 2CO2(g) → 2CO(s) + O2(g) ∆H0= 2*283 KJ/mol= 566kJ/mol
Now, the sum of 2*(1) - 2*(2) produce:
2C(s) + 2O2(g) + 2CO2(g)→ 2CO2(g) + 2CO(g) + O2(g) ∆H0= -788kJ/mol + 566kJ/mol
Subtracting the molecules that ar in both sides of the reaction:
2C(s) + O2(g) → 2CO(g) ∆H0 = -222kJ/mol
2.5 kilogram into gram
Answer:
2500grams
hope this helps
Answer: 2500 gram
Explanation:
Concept:
Here, we need to know the idea of unit conversion.
Unit conversion is the conversion between different units of measurement for the same quantity, typically through multiplicative conversion factors.
1 kg = 1000 g
Solve:
1kg = 1000g
2.5kg = 2.5 × 1000 = 2500g
Hope this helps!! :)
Please let me know if you have any questions
Which of the following statements about periodic trends is true?
O both electronegativity and atomic radius decrease from bottom to top and from left to right on
the periodic table.
O both electronegativity and ionization energy increase from bottom to top and from left to right
on the periodic table.
O both atomic radius and ionization energy increase from bottom to top and from right to left on
the periodic table.
O electronegativity, ionization energy and atomic radius all decrease from bottom to top and from
left to right on the periodic table.
both electronegativity and ionization energy increase from bottom to top and from left to right
on the periodic table.
why water molecules remain associated in liquid water
Answer:
Answer: They are attracted to each other due to their electrostatic attraction. All that means is the hydrogen atom is positively charged, while the oxygen atom is negatively charged. ... The hydrogen of one water molecule will bond to the oxygen atom of another molecule.
Answer:
They are attracted to each other due to their electrostatic attraction. All that means is the hydrogen atom is positively charged, while the oxygen atom is negatively charged. ... The hydrogen of one water molecule will bond to the oxygen atom of another molecule.
Explanation:
A science student observes that a dissolvable antacid tablet acts faster in relieving stomach pain when taken with warm water than when taken with water at room temperature. Based on the observation, suggest a potential problem that can be studied. Also, list the dependent, independent, and controlled variables that can exist in such an investigation.
Answer:
We know that an antacid is a base that can neutralize the stomach acid when ingested. The student observed that a soluble antacid tablet reacted faster in relieving pain due to the excess acid secreted in the stomach. So, the problem that can be studied is the effect of temperature on the rate of neutralization of stomach acid by the antacid. The independent variable is the one the student is going to vary that is the temperature. The dependent variable is the rate of reaction or the time taken for an antacid tablet to neutralize the acid present in stomach. The controlled variable is the tablet taken, that is the student should use a specific antacid tablet to ensure that the rate of reaction or the time taken for the antacid tablet to neutralize the acid present in stomach is not affected by the chemical composition of tablet.
Explanation:
Hope u understood.
Some one please Help and Thank you
Answer:
C is the correct answer
Explanation:
most probably
Look at the two thermometers. Which statement explains which thermometer is more appropriate to measure the temperature of a liquid at 43.6 C
Answer:
I don't know
Explanation: Where are the statements?
Ethylene glycol (antifreeze) has a density of 1.11 g/cm^3. What is the volume (in m^3) of 9.7 tons?(1 ton = 2.000*10^3lb; 1 kg= 2.2046 lb
Answer: The volume of 9.7 tons of given ethylene glycol is 0.0079 [tex]m^{3}[/tex].
Explanation:
Given: Density = 1.11 [tex]g/cm^{3}[/tex]
Mass = 9.7 tons
Convert tons into lb as follows.
[tex]1 ton = 2 \times 10^{3} lb\\9.7 ton = 9.7 ton \times 2 \times 10^{3} \frac{lb}{1 ton}\\= 19.4 \times 10^{3} lb[/tex]
Now, lb is converted into kg as follows.
[tex]1 kg = 2.2046 lb\\1 lb = 0.453592 kg\\19.4 \times 10^{3} lb = 19.4 \times 10^{3} lb \times 0.453592 \frac{kg}{1 lb}\\= 8.79 kg[/tex]
1 kg = 1000 g
So, 8.79 kg = 8790 g
Density is the mass of a substance divided by its volume. Hence, volume of ethylene glycol is calculated as follows.
[tex]Density = \frac{mass}{volume}\\1.11 g/cm^{3} = \frac{8790 g}{volume}\\volume = 7918.92 cm^{3} (1 cm^{3} = 10^{-6} m^{3})\\= 0.0079 m^{3}[/tex]
Thus, we can conclude that the volume of 9.7 tons of given ethylene glycol is 0.0079 [tex]m^{3}[/tex].
What was the main aim of Cavendish’s work?
Answer:
The Cavendish experiment, performed in 1797–1798 by English scientist Henry Cavendish, was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield accurate values for the gravitational constant
Explanation:
I think that's correct
in which instrument of the following the washer works works as a valve? a)syringe b)hydraulic garage lift c)air pump d)watre pump
Answer:
A
Explanation:
The instrument in which the washer works as a valve is A ; syringe
Each instrument listed have a washer and a valve, but of all the instruments listed above the instrument that its washer works also as a valve is the syringe.
A syringe is composed of a thin tube and a thinner hollow needle attached to the end of the thin tube. the needle is used and take in liquids and also expel liquids from the syringe ( i.e. washer and valve )
hence the instrument that its washer also functions as a valve is the syringe.
learn more about syringe : https://brainly.com/question/24283167
how many Molecules and atoms of the product 2H2O+ O2
Answer:
A water molecule is composed of two hydrogen atom and one oxygen atom but you can't simply take two hydrogen atom stick them onto an oxygen atom
When a vacancy exists in an inner electron shell of an atom (as a result of photoelectric effect, Compton scattering, or bombardment by other electrons), the energy liberated when this vacancy is filled, instead of emerging from the atom as fluorescent radiation, can be transferred to another electron of the atom, thereby ejecting the electron. Such an emitted electron is called a(n) _____ electron
Answer:
The answer is "Auger".
Explanation:
The Auger effect is an effect size when the vacancy of even an atom throughout the inner shell was complemented by the release of even an electron from the same atom. Whenever a central electron is lost, a higher energy level electron can drop into the void and release energy, which can be the result.
What is a nucleus please telll me
Answer:
A nucleus is the center of an atom that consists of protons and neutrons. Different elements have a different number of protons and neutrons
Explanation:
Is there law in the United States? Why are black people killed at random by police?
HELP ME ASAPPPP PLZZZZZ!!!!!
For the reaction C + 2H2 → CH4, how many grams of hydrogen are required to produce 16.8 moles of methane, CH4 ?
What is the name of the molecule below
Answer:
2-octene
Explanation:
the 8-carbon chain (oct); has a double bond (ene) is on the 2nd carbon (2-)
What information is obtained from radioactive dating?
- How old something was when it died
- The damage done to an object from radiation
- The age of an object that was once living (ANSWER)
- The lifetime of an isotope in a particular object
Answer:
C
Explanation:
The age of an object that was once living. Hence, option C is correct.
What is radioactive dating?Radioactive dating can be defined as a strategy to date the age of fossils by means of radioactive isotopes.
These methodologies (Radioactive dating) are fundamental for the application field of geologists and palaeontologists.
In conclusion, Radioactive dating refers to the techniques used to date the age of rocks and fossils by radioactive isotopes.
Information related to the age of an object that was once living is obtained from radioactive dating.
Hence, option C is correct.
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Mole concept
Calculate the number of iodine atoms in 4.50g of iodine gas
Answer:
0.017g/mol
Explanation:
according to the mole concept to calculate the number of moles of a substance you use the formula
number of moles= mass/molecular mass
=4.5g/254g/mole
=0.017moles
I hope this helps and sorry if it's wrong
Some consumers, like lions, do not eat plants or any other producers. They only eat other animals. How do lions obtain the carbon they need?
whoever gets it first gets to be Brainlist
Answer:
BHAI SECOND OPTION HOGA
Answer:b
Explanation:
what does high pressure systems usually cause?
Iupac name for this?
Answer:
Explanation:
4,5 diethyl-2 fluoro-3-methylheptanal
calculate the mass of magnesium needed to make 25g of magnesium oxide
mark brainliest of correct xx
Answer:
15g
Explanation:
First, you need to correct the answer to the previous question. The percentage by mass of Mg in MgO =
Mg = 24.3 amu
O = 16.0 amu
The total mass of MgO = 40.3 amu
To calculate the percent composition of Mg:
% = 24.3/40.3 x 100
% = 60
To calculate the mass of Mg needed to make 25g of MgO:
x/25g = 60%/100%
100x = (25)(60)
100x = 1500
x = 15g
Answer in detail?? What precautions would you take to protect yourself from an earthquake, when you are at home and when you are outdoors?
Answer:
If you're indoors, stay inside. If you're outside, stay outside. If you're indoors, stand against a wall near the center of the building, stand in a doorway, or crawl under heavy furniture (a desk or table). Stay away from windows and outside doors.
Answer
Protect your head and neck with a large book, a pillow, or your arms. The goal is to prevent injuries from falling down or from objects that might fall or be thrown at you.If you are able, seek shelter under a sturdy table or desk. Stay away from outer walls, windows, fireplaces, and hanging objects.If you are unable to move from a bed or chair, protect yourself from falling objects by covering up with blankets and pillows.If you are outside, go to an open area away from trees, telephone poles, and buildings, and stay there.How do the substances compare?
The air you breathe is a solution of about 78% nitrogen and 21% oxygen and 1% other
gases. Which substance is the solvent? Explain how you know
Answer:
I believe nitrogen would act as the solvent, I know this because there is a higher percentage of it than oxygen and other.
In the air composition provided, nitrogen is the solvent, while oxygen and the other gases are the solutes dissolved within the nitrogen solvent.
In a solution, the solute is the substance that is present in a smaller quantity and is dissolved in a larger quantity of another substance called the solvent. The solute may dissolve in the solvent to create a homogeneous mixture.
In the given case, air is a mixture of gases, and the major components are nitrogen (78%) and oxygen (21%), with a small percentage of other gases (1%). Here, nitrogen and oxygen are the solutes, and the remaining gases are also solutes, but in a smaller proportion.
The solvent is the component that dissolves the solute, and in the case of air, nitrogen is acting as the solvent. Nitrogen, being the most abundant gas in the mixture, forms the "base" or "carrier" for the other gases to be mixed within. Oxygen and the other gases dissolve or mix into nitrogen gas, creating a homogeneous mixture that we breathe.
Thus, in the air composition provided, nitrogen is the solvent, while oxygen and the other gases are the solutes dissolved within the nitrogen solvent.
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