Answer:
2.5 g mass of Ra-226 will remain after 4800 years.
Explanation:
Given data:
Mass of Ra-226 = 20 g
Sample remain after 4800 years = ?
Solution:
Half life of Ra-226 = 1600 years
Number of half lives passed = T elapsed / half life
Number of half lives passed = 4800 year / 1600 year
Number of half lives passed = 3
At time zero = 20 g
At first half life = 20 g/2 = 10 g
At 2nd half life = 10 g/2 = 5 g
At 3rd half life = 5 g/2 = 2.5 g
Thus, 2.5 g mass of Ra-226 will remain after 4800 years.
7. Base your answer to the following question on the information below and on your knowledge of biology A student designed an experiment to investigate a claim that athletes would have lower heart rates than nonathletes during exercise. After the students classified themselves as an athlete or a nonathlete, their resting pulses were determined. Then all the students performed the same exercise for four minutes and their heart rates were determined by recording the pulse rate in beats per minute. The students continued to measure their pulse rates for an additional four minutes. The average heart rate per minute for each group was determined. The data were recorded, as shown on the table below Average Heart Rate Response to Exercise (beats per minute) Time (minutes) Athlete Students Nonathlete Students Resting Pulse 68 72 1 76 78 2 82 90 Exercising Period 3 115 95 110 4 130 5 100 125 6 95 120 After Exercise 7 85 100 8 68 95 2.4 To improve the validity of the conclusion reached in this experiment, the students should repeat the experiment A) disregarding any data that don't fit the hypothesis B) with a larger number of athletes and nonathletes C) comparing the heart rates and breathing rates of males and females D) with the athletes doing different exercises than the nonathletes
What is the molecular formula of the compound with a molecular weight of 112 g/mol and percent composition: 85.6% C and 14.4% H?
Select one:
a. C2H4
b. CH2
c. C4H8
d. C8H16
Answer:
Molecular formula = C₈H₁₆
Explanation:
Given data:
Percentage of hydrogen = 14.4%
Percentage of carbon = 85.6%
Molecular formula = ?
Molecular weight = 112 g/mol
Solution:
Number of gram atoms of H = 14.4/ 1.01 = 14.26
Number of gram atoms of C = 85.6/ 12 = 7.13
Atomic ratio:
C : H
7.13/7.13 : 14.26/7.13
1 : 2
C : H = 1 : 2
Empirical formula is CH₂
Molecular formula:
Molecular formula = n (empirical formula)
n = molar mass of compound / empirical formula mass
n = 112 / 14
n = 8
Molecular formula = n (empirical formula)
Molecular formula = 8 (CH₂)
Molecular formula = C₈H₁₆
Part of an important cellular process involving a DNA strand is modeled below
12000
What is the purpose of this cellular process?
F Preserving genetic information for future generations
G Deleting the information in the sequence produced from the DNA template
# Transcribing information in the DNA sequence for use by the cell
J Producing more nucleotides for the DNA sequence
Answer: transcribing information to the dna sequence for use by the cell
Explanation:
A scientist thinks he found a new metal, so he published a paper about this metal. About 1 week after the scientist published the paper, you noticed a problem with the paper the scientist wrote. You noticed that this metal was not a new metal. In fact, this metal was discovered years ago. You determined this when you saw the atomic emission spectrum. As you read the article, you remembered that each atomic emission spectrum is unique to each element and the atomic emission spectrum matched one that was already discovered. Using the techniques from Chemistry, you ran a Flame Test with a piece of the metal (the metal is safe to use) that you had shipped to you. You found the metal turned the flame yellow. What metal did you have in your possession?
**ANSWER CHOICES**
*Barium
*Calcium
*Strontium
*Copper
*Sodium
Answer:
Sodium
because it burns with a yellow-orange flame.
Explanation:
It relates with Barium which burns with yellowish green flame
What are some examples of HIGH resistance? Question 2 options:
long wire, wide wire, more resistors
wide wire, short wire, less resistors
long wire, narrow wire, more resistors
narrow wire, less resistors, long wire
(PLEASE HURRY! I NEED TO FINISH THIS QUIZ)
Answer:
long wire, wide wire, more resistors
long wire, narrow wire, more resistors
Explanation:
longer wires have greater resistance. The longer the wire the greater the resistance.
The answer is Long wire, Narrow wire, more resistors
Evidence:
Are scientist improving the plant or corrupting it
Answer:
46 percent of trees have been cut down.
Scienctists helps plants, but humans do destroy a lot of plants.
Scientists - helps increase plant growth.
Woodchoppers - helps decrease plant growth.
What is environment?
Answer:
where an organism lives which includes everything that surrounds and influences the organism.
What is the difference between chlorine -35 and chlorine -37?
Answer:
Free chlorine involves the amount of chlorine that's able to sanitize contaminants, while combined chlorine refers to chlorine that has combined directly with the contaminants. Total chlorine is basically the sum of free chlorine and combined chlorine.
Explanation:
chlorine -35 being chlorine
chlorine -37 being free chlorine
d. what happens when an iron nail is kept in copper sulphate solution?
Answer:
it changes color from blue to light green.
Explanation:
due to copper iron nail functions
Answer:
give the other person brainlieset plz
Explanation:
Which of the following best describes the velocity of an object?
A B0 m/s
B 30 m east
C 30 m/s east
D 30 m/s2
Answer:
[tex]\boxed {\boxed {\sf C. \ 30 \ m/s \ east}}[/tex]
Explanation:
Velocity is the vector measurement of the change in position over time. A vector measurement means the answer must include a magnitude (numerical value) and a direction.
Here are some units of velocity:
m/s (meters per second) kph (kilometers per hour) km/s (kilometers per second)There are many other units, but m/s is the most common.
We can eliminate choice B and D, because the units (meters-m and meters per second squared-m/s²) are not for velocity.
We are left with choice A (30 m/s) and C (30 m/s east). Remember, velocity needs a number and a direction. C contains the direction east, so it must be the correct answer.
Please Help!
Which change takes place at the freezing point of a substance?
Group of answer choices
A. A gas becomes a liquid
B. A solid becomes a gas
C. A liquid become a solid
D. A gas becomes a solid
please also give me an explanation since I do not understand this.
Answer:
❤C. A liquad becomes a solid❤
Explanation:
✌When you freeze water its a scientific fact that it becomes solid.✌
The oxidation # (charge) of an element called "lindenium "Ld is + 1 and the oxidation # (charge) of an element called "mendezine symbol "Mz, is -2. What is the chemical formula for the compound called lindenium mendezide?
Answer:
Ld₂Mz
General Formulas and Concepts:
Chemistry - Compounds
Valence shellsWriting chemical compoundsBalancing chargesExplanation:
Step 1: Define
"Lindenium" Ld w/ oxidation charge of +1
"Mendezine" Mz w/ oxidation charge of -2
Step 2: Write Compound
To balance out the charges to be neutral (0), we must counter balance the amount of Ld's with Mz's. We need 2 Ld's with 1 Mz to create a compound with a neutral charge:
2Ld¹⁺ + Mz²⁻
2(+1) + (-2) = (+2) + (-2) = 0 (neutral charge)
Therefore, our compound must be Ld₂Mz.
During a chemical or physical change, energy may be...
a. created into another form
b. destroyed and reinvented into another form
c. converted into another form
d. disappeared
Answer: C: Converted into another form
Explanation: pues es esa calale y si va a hacer
During a chemical or physical change, energy is converted to another form. Energy cannot be created or destroyed. During a chemical reaction, physical change the energy and mass are conserved.
What is law of conservation of energy ?According to the law of conservation of energy energy can neither be crated nor be destroyed. Hence, the total energy of a system is always conserved.
However, energy can be transformed from one form to the other. Therefore, the energy lost in one form is gained in another form. For example, in all electrical devices, the electrical energy is converting to other forms of energy such as light, thermal , mechanical etc.
Similarly, during a chemical reaction, the energy released by a reaction system is equal to the energy absorbed by other reacting system. Similarly in electrochemical cells the chemical energy is converting to electrical energy.
Find more on energy transformation:
https://brainly.com/question/17589256
#SPJ6
HELPP ASAP
What do the colors on the periodic table show?
A. which element it is
B. the metallic properties of the element
C. the types of compounds the element can make
D. whether the element is a solid, a liquid, or a gas at room temperature
Answer:
Periodic tables can use color to identify other element characteristics. For example, an electronegativity periodic table color codes the elements based on how electronegative they are. The valence periodic table uses color to identify the most common valence state for each element.Oct 2, 2019
pls like and rate us .
The color given to a the elements in periodic table is to characteristics of the elements mainly to identify whether they are solid, gas or liquid. Thus option D is correct.
What is periodic table?A periodic table contains all the discovered elements which are classified into different groups and periods. Groups are vertical columns of elements with similar properties and same number of valence electrons.
Periods are horizontal rows from left to right with an increase in atomic number. There are 18 groups and 7 periods in periodic table. Each group has given each color and some elements showing exceptional characteristics such as hydrogen and helium have separate colors.
All the first group elements called alkali metals have one color and the second groups elements with another color, All the d-block elements are given the same colour and metals in p-block elements have the same color.
Similarly, all the metalloids have one color and all other gases have the same colour in which inert gas group and halogen group have seperate colours.
Hence, the color in periodic table helps to identify the element's nature like its state also. Thus option D is correct.
To find more about periodic table, refer the link below:
https://brainly.com/question/11155928
#SPJ2
How many rings/energy levels would the Bohe model for an element
have if it had 12 electrons?
PLEASE HELP
why sodium and chlorine are active element
SOMEONE HELP ME PLEASE!!! ILL GIVE BRAINLY
Physical properties behave identically for all matter under the same conditions.
Physical properties cause atoms and molecules to change structure when substances are mixed.
Physical properties can be observed without changing the identity of a substance.
Physical properties are observed by seeing how a substance reacts with other substances.
Answer:
the answer is c
Explanation:
My reasoning is that its most likely
ill attach a picture
Answer:
35.50
Explanation:
There are two stable isotopes, 35Cl (75.77%) and 37Cl (24.23%), giving chlorine a standard atomic weight of 35.45
if a car travels 350 miles in 7 hours what was the speed
Answer:
50 mph
Explanation:
Answer:
5 miles per hour
Explanation:
TRUST ME
Reaction type
Li + N2
Li3N
Answer:
Combination or synthesis
Explanation:
The given reaction is:
6Li + N₂ → 2 Li₃N
This reaction is a synthesis or combination reaction. 6 moles of Li combines with nitrogen gas to produce 2 moles of Li₃N.
In a synthesis reaction, two substances combines together to give singular product. The formation of compounds from the union of the constituent elements falls into this category of reaction.4. (10 Points) Write a single replacement reaction where one of the reactants is
ammonium nitrate.
Include the states of matter for each of the reactants and products.
Answer:
For each balanced reaction, indicate the total number of atoms in the table below. Reaction. Total Number of Atoms. Reactant Side 1 Product Side. (Left).
Explanation:
An object is moving across a surface, but it does not gain or lose speed. Which best describes the object’s force?
Answer:
Explanation:
the vector sum of all such forces which equals zero for an object at rest. CASE 1: Considering a basketball of weight 1kg, if it has been kept stationary on the ground, there are two forces acting on it. These are it's weight (gravity) and equal and opposite force from the ground (normal reaction).
Answer:
The net force is zero. :)
Explanation:
C3H5OH + 3 O2 --> CO2 + H2O When balancing the equation above, how many molecules of CO2 and H2O are produced? The first half is already balanced.
Answer:
1.8069*10²⁴molecules of CO₂ and H₂O are produced.
Explanation:
C₃H₅OH + O₂ → CO₂ + H₂O
The law of conservation of matter states that since no atom can be created or destroyed in a chemical reaction, the number of atoms that are present in the reagents has to be equal to the number of atoms present in the products.
Then, you must balance the chemical equation. For that, you must first look at the subscripts next to each atom to find the number of atoms in the equation. If the same atom appears in more than one molecule, you must add its amounts
Left side: 3 C, 6 H and 3 O.
Right side: 1 C, 2 H and 3 O.
The coefficients located in front of each molecule indicate the amount of each molecule for the reaction. This coefficient can be modified to balance the equation, just as you should never alter the subscripts.
By multiplying the coefficient mentioned by the subscript, you get the amount of each element present in the reaction.
So, balancing the C:
C₃H₅OH + O₂ → 3 CO₂ + H₂O
Then:
Left side: 3 C, 6 H and 3 O.
Right side: 3 C, 2 H and 7 O.
Now, balancing the H:
C₃H₅OH + O₂ → 3 CO₂ + 3 H₂O
Then:
Left side: 3 C, 6 H and 3 O.
Right side: 3 C, 6 H and 9 O.
Finally, balancing the O:
C₃H₅OH + 4 O₂ → 3 CO₂ + 3 H₂O
Then:
Left side: 3 C, 6 H and 9 O.
Right side: 3 C, 6 H and 9 O.
Since you have the same amount of each element on each side of the reaction, the reaction is balanced. Then 3 moles of CO₂ and 3 moles of H₂O are produced.
Avogadro's Number or Avogadro's Constant is called the number of particles that make up a substance (usually atoms or molecules) and that can be found in the amount of one mole of said substance. Its value is 6.023*10²³ particles per mole and it applies to any substance.
Then the following rule of three applies: if 1 mole contains 6.023*10²³ molecules, then 3 moles of CO₂ or 3 moles of H₂O, how many molecules does it contain?
[tex]amount of molecules=\frac{3 moles* 6.023*10^{23} molecules}{1 mole}[/tex]
amount of molecules= 1.8069*10²⁴
1.8069*10²⁴ molecules of CO₂ and H₂O are produced.
what makes one of your cells you ?
What is the mass of 2.25 mol of the element Iron (Fe)?
Choose the correct set up from the given choices.
a. You would divided 2.25 mol by (55.84 mol divided by 1 gram)
b. You would multiply 2.25 mol by (1mol divided by 55.84 g)
c. You would multiply 2.25 mol by (55.84g divided by 1 mol)
d. You would divide 2.25 mol by (1 mol divided by 55.84g)
Mole measure the number of elementary entities of a given substance that are present in a given sample. To find mass of 2.25 mol of the element Iron (Fe), we multiply 2.25 mol by (55.84g divided by 1 mol). Therefore option c is correct option.
What is mole?The SI unit of amount of substance in chemistry is mole. The mole is used to measure the quantity or amount of substance.
Mathematically,
Mole of Fe element= mass of Fe element÷ Molar mass of Fe element
mass= Mole of Fe element ×Molar mass of Fe element
Substituting the given values in above formula we get
mass= 2.25 mol× 55.84 g/mole
mass= 2.25 mol× 55.84 g/mole
To find mass of 2.25 mol of the element Iron (Fe), we multiply 2.25 mol by (55.84g divided by 1 mol).
Therefore option c is correct option.
To know more about mole, here:
https://brainly.com/question/15209553
#SPJ2
Which of the following scenarios would not prompt the cell to start dividing
Answer:
what r the options??????
What do the elements in group 18 have in common?
Answer: They are all odorless, colorless, monatomic gases with very low chemical reactivity.
Explanation: Plz give brainliest
what is love made out of ?
What did you include in your response? Check all that
apply.
O No, thermal energy is not being transferred by
radiation in this image.
O The eggs are in direct contact with the metal pan,
which is in direct contact with the gas flame.
O Thermal energy is being transferred by conduction.
O Radiation transfers thermal energy by
electromagnetic waves.
O Radiation does not transfer thermal energy by
direct contact.
equivalent mass of AL2O3
Answer:
[tex]Mass = 102g[/tex]
Explanation:
Given
Compound: [tex]Al_2O_3[/tex]
Required
Determine the equivalent mass
In the above compound, we have: 2 Al and 3 (O)
The atomic mass of Aluminium is:
[tex]Al = 27[/tex]
The atomic mass of Oxygen is:
[tex](O) = 16[/tex]
So, the equivalent mass is:
[tex]Mass = 2 * 27 + 3 * 16[/tex]
[tex]Mass = 54 + 48[/tex]
[tex]Mass = 102g[/tex]