1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Shkiper50 [21]
3 years ago
15

If a sample has 25% parent and 75% daughter, how many halflifes have gone by?

Chemistry
1 answer:
Anit [1.1K]3 years ago
6 0

Answer:

Two half lives.

Explanation:

It is known that the decay of isotopes and radioactive material obeys first order kinetics.

Also, it is clear that in first order decay the half-life time is independent of the initial concentration.

That means for a sample 100% to decay to 50 % it will take one half-life, and to decay the remaining 50% to 25% it will take another half-life.

So, for a sample has 25% parent and 75% daughter it will have two half-lives.

You might be interested in
What will a balloon do to a cloth if its negatively charged
masya89 [10]

Answer:

This involves negatively charged particles (electrons) jumping to positively charged objects. When you rub the balloons against the fabric they become negatively charged. They take some of the electrons from the fabric and leave them positively charged.

Explanation:

Negative charges attract to positive charges. If a balloon is not rubbed with the wool cloth, it has an equal amount of negative to positive charges, so it will attract to a rubbed balloon. When both balloons are rubbed with the wool cloth, the both receive negative charges, so they will repel each other.

3 0
2 years ago
Which of the following is a physical change. A piece of magnesium metal formed bubbles when dropped in acid
uysha [10]

H2O became a vapor when heated because thats the only one that can go back to its normal state, which is what a physical change is.


3 0
2 years ago
Calcium carbide, CaC2, reacts with water to form calcium hydroxide and the flammable gas ethyne (acetylene) in the reaction: Wha
AysviL [449]

Answer:

1 mole of CaC₂ will produce 26g of C₂H₂ or 64.1g of CaC₂ will produce 26g of C₂H₂

Explanation:

Hello,

To solve this question, we'll require a balanced chemical equation of reaction between calcium carbide and water.

Equation of reaction

CaC₂ + 2H₂O → Ca(OH)₂ + C₂H₂

Molar mass of calcium carbide (CaC₂) = 64.1g/mol

Molar mass of water (H₂O) = 18g/mol

Molar mass of calcium hydroxide (Ca(OH)₂) = 74g/mol

Molar mass of ethyne (C₂H₂) = 26g/mol

From the equation of reaction, 1 mole of CaC₂ will produce 1 mole of C₂H₂

1 mole of CaC₂ = mass / molar mass

Mass = 1 × 64.1

Mass = 64.1g

1 mole of C₂H₂ = mass / molar mass

Mass = 1 × 26

Mass = 26g

Therefore, 1 mole of CaC₂ will produce 26g of C₂H₂

Note: this is a hypothetical calculation since we were not given the initial mass of CaC₂ that starts the reaction

7 0
2 years ago
A box has a weight of 120 lbs and the bottom of the box is 12 in2 . What is the pressure the box exerts on the floor?
denis23 [38]
How can I help with this question?
7 0
2 years ago
A solid substance turns into a liquid. Which best describes this change?
nordsb [41]
Melting? not really sure what type of answer they are going for but the substance is going through the melting phase
8 0
2 years ago
Read 2 more answers
Other questions:
  • The type of chemical bond that involves the transfer of electrons between atoms is a(n) bond.
    10·2 answers
  • What can be said about a reaction with H = 62.4 kJ/mol and S = 0.145 kJ/(mol·K)?
    6·2 answers
  • Students in a science class learn that groundwater is an important source of drinking water for many communities. They construct
    5·1 answer
  • How many moles is 24 grams of carbon?
    14·2 answers
  • Ty and Crystal are working together to learn about surface tension.
    5·1 answer
  • you are studying an element that is a gas at room temperature. Is it most likely a metal, nonmetal, or metalloid?
    7·2 answers
  • If an atom has 29 electrons and a mass of 64, and it is neutral, what is the name of the atom?
    11·1 answer
  • When dissolved substances are spread evenly throughout a mixture it is called a
    7·2 answers
  • Pls help me also pls have the correct answer
    5·2 answers
  • Which statement is true regarding the function of a catalyst in a chemical reaction?.
    10·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!