Answer:
The half-life of a radioisotope describes the amount of time it takes for said isotope to decay to one-half the original amount present in the sample.
Nitrogen-13, because it has a half-life of ten minutes, will experience two half-lives over the course of the twenty minute period. This means that 25% of the isotope will remain after this.
0.25 x 128mg = 32mg
32mg of Nitrogen-13 will remain after 20 minutes.
Which branch of chemistry would be used to make steel?
Answer:
the five major branches of chemistry are organic, inorganic, analytical, physical, and biochemistry.
How hot will a 2.5 L balloon have to get to expand to a volume of 5 L? Assume that the initial temperature of the balloon is 22 C?
The final temperature : 317 °C
Further explanationGiven
V₁=2.5 L
V₂ = 5 L
T₁ = 22 + 273 = 295 K
Required
The temperature, T₂
Solution
Charles's Law
When the gas pressure is kept constant, the gas volume is proportional to the temperature
[tex]\tt \dfrac{V_1}{T_1}=\dfrac{V_2}{T_2}[/tex]
Input the value :
T₂ = (T₁ x V₂) : V₁
T₂ = (295 x 5) : 2.5
T₂ = 590 K = 317 °C
how does heat transfer into conduction
Explanation:
Heat is transferred by conduction when adjacent atoms vibrate against one another or electrons move from one atom to another . Conduction is the most significant meanings of heat transfer within a solid or between solid objects informal contact.
The half-life of sodium-24 is 15 days. A laboratory technician measures out a 72 g sample. Approximately how many grams of sodium-24 would remain after 45 days?
Answer:
after 45 days 9 g left
Explanation:
Given data:
Half life Na-24 = 15 days
Mass of sample = 72 g
Mass remain after 45 days = ?
Solution:
Number of half lives passed:
Number of half lives = time elapsed / half life
Number of half lives = 45 days / 15 days
Number of half lives = 3
At time zero total amount = 72 g
After first half life = 72 g/ 2= 36 g
At 2nd half life = 36 g/2 = 18 g
At 3rd half life = 18 g/2 = 9 g
Thus after 45 days 9 g left.
Draw the reactants and complete the mechanism by drawing in the appropriate electron-flow arrows (including stereochemistry) for the following SN2 reaction of an alkyl bromide. Represent the nucleophile as an ion. Draw all missing reactants and/or products in the appropriate boxes by placing atoms on the grid and connecting them with bonds, including charges where needed. Indicate the mechanism by drawing the electron-flow arrows on the molecules. Arrows should start on an atom or a bond and should end on an atom, bond, or where a new bond should be created.
Answer:
Wow I don't that hhehehe sorry
Please help me thanks so much....I’ll mark you?!?!:)))) ( 15 points)
Answer:
all of the above
Explanation:
Suppose a current of is passed through an electroplating cell with an aqueous solution of agno3 in the cathode compartment for seconds. Calculate the mass of pure silver deposited on a metal object made into the cathode of the cell.
The given question is incomplete. The complete question is:
Suppose a current of 0.920 A is passed through an electroplating cell with an aqueous solution of agno3 in the cathode compartment for 47.0 seconds. Calculate the mass of pure silver deposited on a metal object made into the cathode of the cell.
Answer: 0.0484 g
Explanation:
[tex]Q=I\times t[/tex]
where Q= quantity of electricity in coloumbs
I = current in amperes = 0.920 A
t= time in seconds = 47.0 sec
[tex]Q=0.920A\times 47.0s=43.24C[/tex]
[tex]AgNO_3\rightarrow Ag^++NO_3^-[/tex]
[tex]Ag^++e^-\rightarrow Ag[/tex]
96500 Coloumb of electricity electrolyzes 1 mole of Ag
43.24 C of electricity deposits =[tex]\frac{1}{96500}\times 43.24=0.00045moles[/tex] of Ag
[tex]\text{ mass of Ag}={\text{no of moles}\times {\text{Molar mass}}=0.00045mol\times 108g=0.0484g[/tex]
Thus the mass of pure silver deposited on a metal object made into the cathode of the cell is 0.0484 g
What would be the mass of 9.03 x 10^21 molecules of hydrobromic acid?
1.21 g HBr
General Formulas and Concepts:Math
Pre-Algebra
Order of Operations: BPEMDAS
Brackets Parenthesis Exponents Multiplication Division Addition Subtraction Left to RightChemistry
Compounds
Writing CompoundsAcids/BasesAtomic Structure
Reading a Periodic TableUsing Dimensional AnalysisAvogadro's Number - 6.022 × 10²³ atoms, molecules, formula units, etc.Explanation:Step 1: Define
9.03 × 10²¹ molecules HBr
Step 2: Identify Conversions
Avogadro's Number
Molar Mass of H - 1.01 g/mol
Molar Mass of Br - 79.90 g/mol
Molar Mass of HBr - 1.01 + 79.90 = 80.91 g/mol
Step 3: Convert
Set up: [tex]\displaystyle 9.03 \cdot 10^{21} \ molecules \ HBr(\frac{1 \ mol \ HBr}{6.022 \cdot 10^{23} \ molecules \ HBr})(\frac{80.91 \ g \ HBr}{1 \ mol \ HBr})[/tex]Multiply/Divide: [tex]\displaystyle 1.21325 \ g \ HBr[/tex]Step 4: Check
Follow sig fig rules and round. We are given 3 sig figs.
1.21325 g HBr ≈ 1.21 g HBr
The process by which cells divide is called
A
O replication
B.
mitosis
C.
respiration
D.
photosynthesis
the answer is mitosis
HELP I need these 2 questions answered
Answer:
1=a 2=d i think
Explanation:
A substance made up of two or more types of atoms that are NOT chemically combined is called a(n)
A
element
B
mixture
с
compound
D
pure substance
Answer:
pure substance
Explanation:
it does not combine to anything.
what problems occurs if the firework mixture is not pure(they are dirty or contaminated?
Firework mixture is made up with potassium nitrate and other toxic chemicals. They produce harmful wastes to the atmosphere. If they are contaminated, they make release very dangerous explosives by unwanted reactions.
What are explosives?Explosives are chemicals releasing lot of heat energy to the surrounding upon decomposition. Nitrogen compounds, hydrogen etc are explosive and they will explode in air or water.
Chemicals have to handled carefully and stored as per the conditions based on their chemical and physical properties. Some of them may easily corrode. Some may rapidly reacts with water or air and some may explode in air.
Explosive chemicals causes atmospheric pollution as well as health risk by releasing hazardous chemicals. If they are contaminated then there may occur some unwanted reaction and it will make the risk intense by producing toxic gases.
To find more about explosives, refer here:
https://brainly.com/question/8735140
#SPJ2
Touching a hot stove or the melting of ice in your hand (as you squeeze it) is an example of
Answer: conduction
Explanation:
the heat passes out of the stove and into your hand. So is holding an ice cube – the heat is conducted out of your hand, and into the ice cube (that’s why your hand feels cold).
Answer:
Conduction
Explanation:
Conduction occurs when objects touch. The heat from the warmer object is transferred to the cooler object, eventually evening out the temperatures.
The frequency of the stretching vibration of a bond in IR spectroscopy depends on what two quantities?
Answer:
Strength of the bond
Masses of the bonded atoms.
Explanation:
The lack of such groups means that they are not endogenous in the concentrate. 1. A bond's spreading frequency relies on the frequency of the bond and the concentrations of the atoms that are bonded.
at a particulat temperature, a smaple of pure water has a Kw of 7.7x10-14. what is the hydroxide concentration of this sample
Answer: The hydroxide concentration of this sample is [tex]3.85\times 10^{-7}[/tex]
Explanation:
When an expression is formed by taking the product of concentration of ions raised to the power of their stoichiometric coefficients in the solution of a salt is known as ionic product.
The ionic product for water is written as:
[tex]K_w=[H^+]\times [OH^-][/tex]
[tex]7.7\times 10^{-14}=[H^+]\times [OH^-][/tex]
As [tex][H^+]=[OH^-][/tex]
[tex]2[OH^-]=7.7\times 10^{-14}[/tex]
[tex][OH^-]=3.85\times 10^{-7}[/tex]
Thus hydroxide concentration of this sample is [tex]3.85\times 10^{-7}[/tex]
What type of succession takes place when a community starts to grow?
A. Primary
B. Secondary
Answer:
Primary
Explanation:
Succession is a series of progressive changes in the composition of an ecological community over time. In primary succession, newly exposed or newly formed rock is colonized by living things for the first time.
What causes a spectrum of colors to appear when light moves through a prism?
Absorption of light waves
O Refraction of light waves
Transmission of light waves
Reflection of light waves
Answer:
It is refracted out, B
Explanation:
When the light travels through the prism, it refracts the colors out of it. In which a rainbow sort coloration is released from the other side.
Answer:
Explanation:
Refraction of light waves
The number of light waves that occur in one second is known as the wave's
Question 2 options:
amplitude
frequency
energy
movement
Answer:
b
Explanation:
I did this quiz and i think a got it right i also looked up my answer to make sure it was right good luck on quiz :)
How many grams are in 4.7 moles of Na2O?
290 g Na₂O
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 TableUsing Dimensional AnalysisExplanation:Step 1: Define
4.7 mol Na₂O
Step 2: Identify Conversions
Molar Mass of Na - 22.99 g/mol
Molar Mass of O - 16.00 g/mol
Molar Mass of Na₂O - 2(22.99) + 16.00 = 61.98 g/mol
Step 3: Convert
Set up: [tex]\displaystyle 4.7 \ mol \ Na_2O(\frac{61.98 \ g \ Na_2O}{1 \ mol \ Na_2O})[/tex]Multiply: [tex]\displaystyle 291.306 \ g \ Na_2O[/tex]Step 4: Check
Follow sig fig rules and round. We are given 2 sig figs.
291.306 g Na₂O ≈ 290 g Na₂O
what is the periodic table elements
Answer:
Here is a picture of all the elements
Answer:
The periodic table is a tabular array of the chemical elements organized by atomic number, from the element with the lowest atomic number, hydrogen, to the element with the highest atomic number, oganesson. The atomic number of an element is the number of protons in the nucleus of an atom of that element.
Explanation:
PLEASE MARK ME AS BRAINLIEST
List the four forms of acid deposition.
Explanation:
rain, snow, cloud, fog or dry deposition - Dry particles, or gas
The isotope carbon-14 decays over time into nitrogen-14 with a half-life of 5,730 years. Suppose that you find a fossil that contains 1.25 grams of carbon-14 and 3.75 grams of nitrogen-14. How old is the fossil
Answer:
11460 years
Explanation:
0.693/t1/2 = 2.303/t log (No/N)
t1/2 = half life of the carbon
t = age of the fossil
No= amount of radioactive material originally present
N= amount of radioactive material present at time=t
No= mass of carbon + nitrogen = 5g
0.693/5730 = 2.303/t log (5/1.25)
1.21 ×10^-4 = 1.3866/t
t= 1.3866/1.21 ×10^-4
t= 11460 years
Suppose a psychrometer reads 80°F for the dry bulb and 76°F for the wet bulb. What is the relative humidity?
Answer: 84%
Explanation:
Using the table attached, one can find out the Relative humidity.
Look at the intersection between the temperature on the dry bulb and the difference between the temperature on the dry and wet bulb.
Dry bulb temperature = 80°F
Wet bulb temperature = 76°F
Difference = 80 - 76 = 4°F
Relative humidity is therefore:
= 84%
An aqueous solution of 6.70 M ammonia, NH3, has a density of 0.950 g/mL. The percent by mass of NH3 in the solution is %.
Answer:
12.01% by mass
Explanation:
Percent by mass is 100 times the mass of solute (ammonia) over the mass of the solution. In molarity, we have the moles of ammonia per liter of solution. There are 6.70moles of NH3 in 1L. Thus, we need to convert the moles of ammonia to grams and the liters of solution to grams:
Mass ammonia - Molar mass: 17.031g/mol-
6.70moles * (17.031g / mol) = 114.1g NH₃
Mass solution:
1L * (1000mL / 1L) = 1000mL * (0.950g/mL) = 950g
Percent by mass:
114.1g NH₃ / 950g * 100 =
12.01% by massSome organisms are composed of only ONE cell. *
O True
O false
How does an objects speed affect its kinetic energy?
what is a benefit of the artificial selection for the environment and explain it. please help!!
1x+cb=23
thios is right because math
which element is the least reactive? Neon, Chlorine, Gallium or Tin
A student is investigating potential and kinetic energy by stretching a spring across a table. When the student lets go
The spring recoils.
Answer: When the spring is recoiling
Explanation:
Answer:
When the spring is recoiling
Explanation:
Which ball has the greatest potential energy?
Ball A
Ball B
Ball
All of the balls have the same amount of potential energy