Answer:
It takes 6h to the radioactive source decrease its activity from 200 to 25
Explanation:
The equation that describes the readioactive decay is:
Ln [A] = -kt + Ln [A]₀
Where [A] could be taken as activity of the source after time t, [A]₀ is initial activity and k is decay constant.
Decay constant could be written as:
k = ln2 / Half-life
k = ln 2 / 2h
k = 0.3466h⁻¹
Replacing in decay equation:
Ln [25] = -0.3466h⁻¹t + Ln [200]
-2.0794 = -0.3466h⁻¹t
6h = t
It takes 6h to the radioactive source decrease its activity from 200 to 25
What coefficient should go in front of the hydrogen peroxide (H2O2 ) molecule to make the chemical equation balanced? ___ H2O2 ➞ 2 H2O + O2
Answer:
2
Explanation:
H2O2 ➞ 2 H2O + O2
The reaction is currently not balanced because the number of atoms on the reactant side is not equal to that of the product side
Hydrogen
Reactant = 2 Product = 4
Oxygen
Reactant = 2 Product = 4
Adding 2 to H2O2 balances the reaction as the number of atoms of both elements are now balanced on both sides of the equation
2H2O2 ➞ 2 H2O + O2
what is an acid containg oxygen?
Explanation:
An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H+ cation and the anion of the acid.
Answer:
oxyacid, oxoacid
Explanation:
An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H+ cation and the anion of the acid.
Explain why hydrocarbons are present in so many different compounds.
Answer:
Many hydrocarbons are found in plants, animals, and their fossils; other hydrocarbons have been prepared in the laboratory. We use hydrocarbons every day, mainly as fuels, such as natural gas, acetylene, propane, butane, and the principal components of gasoline, diesel fuel, and heating oil.
Ammonia (NH3) reacts with oxygen (O2) to produce water and nitric oxide (NO). How many grams of water are produced when 22.5 grams of oxygen are reacted?
Explain why is ortho nitrophenol more acidic than ortho methoxyphenol
Answer:
Ortho nitrophenol is more acidic than ortho-methoxyphenol.
Reason:
This is because the nitro-group is an electron-withdrawing group. In the case of ortho methoxyphenol; methoxy group is an electron-releasing group. Thus, it increases the electron density in the O−H bond and hence, the proton cannot be given out easily.
Hope this helps you. Do mark me as brainliest.
Can someone please help
Answer:
Water is the answer
Explanation:
Plants cannot grow too close together because their Blank______ need to spread out and absorb nutrients from the soil.
their roots need room to spread out
What are two properties that make a metal a good choice to use a wire in electronics? *
Answer:
Explanation:
The two properties that make a metal a good choice to use a wire in electronics are :
ductility conductivityThomas sits half way down a grassy slope. What force stopped him slamming down
anyone know this? i’m having trouble...please help.
In order to produce CO2, a student put a sample of calcium carbonate in a flask and added hydrochloric acid using the following equation: Ca(CO3) + HCl → H2O + CO2 + CaCl2 The student finds the mass of CO2 generated to be 100 g. If the student began with 200 g of HCl and there was ample CaCO3 left unreacted, what was the percent yield?
Answer:
82.9% Is the percent yield
Explanation:
First, we need to balance the equation.
Ca(CO3) + 2HCl → H2O + CO2 + CaCl2
Since the problem tells you that the excess reactant is Ca(CO3), we just need to Stoichiometry to solve for the theoretical yield.
[tex]\frac{200g HCl}{1}[/tex] x [tex]\frac{1 mole HCl}{36.46gHCl}[/tex] x [tex]\frac{1 mol CO2}{2molHCl}[/tex] x [tex]\frac{44.01CO2}{1molCO2}[/tex] =120.707 g (theoretical yield)
Take your actual yield of 100g, divide that by 120.707, then multiply that decimical by 100.
A cup of coffee is made in the morning by pouring water ov er ground up coffee beans in a piece of paper and by collecting the brown liquid that comes through. Which techniques used
Answer: Filtration technique
Explanation:
The technique used here is called filtration.
Filtration,is a physical separation process that separates a mixture of an insoluble solid from a liquid ( acting as the solvent) by the use of a filter barrier that allows only the fluid to pass through.
In the case from the question,
As water is poured over the ground coffee, it forms a mixture of which the insoluble solid is the coffee grounds, the water is the liquid and the filter barrier is the piece of paper which allows only the brown liquid coffee to pass through as the filtrate.
How many atoms of cobalt are in 4 moles of cobalt?
2 × 10²⁴ atoms Co
General Formulas and Concepts:Math
Pre-Algebra
Order of Operations: BPEMDAS
Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to RightChemistry
Atomic Structure
Reading a Periodic TableAvogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.Stoichiometry
Using Dimensional AnalysisExplanation:Step 1: Define
4 mol Co (Cobalt)
Step 2: Identify Conversions
Avogadro's Number
Step 3: Convert
Set up: [tex]\displaystyle 4 \ mol \ Co(\frac{6.022 \cdot 10^{23} \ atoms \ Co}{1 \ mol \ Co})[/tex]Multiply/Divide: [tex]\displaystyle 2.4088 \cdot 10^{24} \ atoms \ Co[/tex]Step 4: Check
Follow sig fig rules and round. We are given 1 sig fig.
2.4088 × 10²⁴ atoms Co ≈ 2 × 10²⁴ atoms Co
What is the molecular formula for C5H7 if its molar mass is 536 g/mol?
Answer:
(C5H7)8
Explanation:
It's empirical formula is given as; C5H7
Molar mass of carbon(C) = 12 g/mol
Molar mass of hydrogen(H) = 1 g/mol
We are told that it's molar mass is 536 g/mol.
To find the molecular formula;
Molecular formula = n × empirical formula
Thus;
n = 536/((12 × 5) + (1 × 7))
n = 8
Thus;
Molecular formula = (C5H7)8
What is the SI unit of time?
A.
second
B.
minute
C.
hour
D. day
Answer:
option a. second
.............
What do plants need in order to make food?
A. water, energy, oxygen
B.carbon dioxide, energy, oxygen
C.water, energy, carbon dioxide
D.water, oxygen, carbon dioxide
Answer:
Water, solar energy, carbon dioxide
Explanation:
This image models…
diffraction
reflection
refraction
absorption
Answer:
reflection is correct answer by my views
Some seawater is evaporated. The sea salt obtained is found
to be 86% sodium chloride. How much sodium chloride
could be obtained from 200 g of this salt?
Answer:
the answer is 172g
Explanation:
200 × 0.86 = 172g
Question 19 Multiple Choice Worth 3 points)
(06.04 MC)
What forensic scientist established the 'Body Farm' to study the ways bodies decompose under different circumstances?
Matheiu Orfila
Sir Edward Henry
Phillipe Locard
Bill Bass
Answer:
The answer is D Bill Bass
Explanation:
Remember it from the lesson and I took the test.
A student says that since the atomic theory is just a theory, it should not be considered useful. Which
statement best argues against the student's opinion? (2 points)
O Scientific theories change over time.
O Scientists often do not agree about specific details of scientific theories.
O Scientists often propose competing theories.
O Scientific theories do not become Scientific Laws.
O Scientific theories are the results of many experiments and observations.
Answer:
O Scientific theories are the results of many experiments and observations.
Explanation:
Going through the options;
O Scientific theories change over time.
This is true and supports the student's opinion. So wrong option!
O Scientists often do not agree about specific details of scientific theories.
This is true. However, it supports the student's opinion. So wrong option!
O Scientists often propose competing theories.
This is true. However, it supports the student's opinion. So wrong option!
O Scientific theories do not become Scientific Laws.
This is False. Theories that have withstood the test of time and countless experiments become laws. However it support's the student's opinion. So wrong option!
O Scientific theories are the results of many experiments and observations.
This is true and is against the student's opinion. This option is correct!
Which type of plate boundary is associated with seafloor spreading at the source of the spread: convergent, divergent, or transform?
Answer:
The answer is divergent
Which characteristic is true of sexual reproduction but not of asexual reproduction?
Answer:
j one or more parents. that's the answer
How does water pressure relate to depth?
how many molecules are in SO4
Answer:
there are 5 molecules in SO⁴
6) The following questions refer to F2 and Cl2.
a. Draw the molecular model (space-filling or ball-and-stick) that would
provide the best means for comparing the differences in bond length and
bond energy.
b. Which structure has the longest bond length? Justify your answer.
c. Which bond has the greatest bond energy? Justify your answer.
d. Which structure has the least potential energy associated with its bond?
Justify your answer.
Answer:
chill
Explanation:
How many grams are in 0.75 moles of Fe
Answer:
41.88375 g Fe
Explanation:
Using stoichiometry, we can do this problem. First, we put our given. Then we create an equation using the molar mass of Fe (found on the periodic table, which was 55.845 g Fe), and the resulting equation is:
[tex]0.75 mol Fe * \frac{55.845 g Fe}{1 mol Fe}[/tex]
The mol Fe's cancel, and leave us with:
41.88375 g Fe
Good luck.
A violent disturbance in the atmosphere is a
eye of hurricane
surge
front
storm
Answer: Storm surge
Explanation:
What season is it in earths northern hemisphere when earths northern hemisphere tilts toward the sun
Answer:
Summer
Explanation:
Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays. So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere.
Hope it helped!! Please mark as Brainliest!
Answer:
Summer took the test and got it right
Explanation:
Which season will the northern hemisphere experience when the axis of Earth is tilted towards the sun?
Summer
Based on the table above, which amount of a compound dissolved in 100 grams of water at the stated temperature represents a system at equilibrium?
Select one:
a. 40 g NaCl at 70 degrees Celsius
b. 20 g KClO3 at 70 degrees Celsius
c. 80 g NaNO3at 10 degrees Celsius
d. 80 g Pb(NO3)2 at 30 degrees Celsius
Answer:
C. 80g Nano3 at 10 degrees Celsius
Explanation:
I just took the test
80 g NaNO₃ at 10 degrees Celsius of a compound dissolved in 100 grams of water at the stated temperature represents a system at equilibrium. Therefore, option C is correct.
What is solubility ?The maximum quantity of a chemical that will dissolve in a given amount of solvent at a particular temperature is referred to as its solubility.
Different compounds have very varying solubilities, which is a feature of a particular solute-solvent pair.
A substance's physical and chemical characteristics affect how soluble it is. A few other factors and circumstances can also influence it. A few of these are: temperature, pressure, kind of binding, and forces between the particles.
A system is said to be in equilibrium when 80 grammes of a substance, dissolved in 100 grams of water at 10 degrees Celsius.
Thus, option C is correct.
To learn more about the solubility, follow the link;
https://brainly.com/question/28170449
#SPJ2
A typical tincture of iodine contains about 2.0% iodine by mass. Calculate
the mass of iodine in a 500. g tincture.