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
Lelu [443]
3 years ago
9

What is the half-life of an isotope that decays to 6.25% of its original activity in 18.9 hours?

Chemistry
1 answer:
inessss [21]3 years ago
8 0
Radioactive material obeys 1st order decay kinetics,
For 1st order reaction, we have 
k = \frac{2.303}{t}Xlog \frac{\text{initial conc.}}{\text{final conc.}}
where, k = rate constant of reaction

Given: Initial conc. 100, Final conc. = 6.25, t = 18.9 hours

∴ k = \frac{2.303}{18.9} X log \frac{100}{6.25} = 0.1467 hours^(-1)

Now, for 1st order reactions: half life = \frac{0.693}{k} =  \frac{0.693}{0.1467} = 4.723 hours.


You might be interested in
Which of the following processes does our Sun and other stars in our galaxy use to create energy?
Usimov [2.4K]

Answer:

fusion reaction

The simple answer is that the sun, like all stars, is able to create energy because it is essentially a massive fusion reaction. Scientists believe that this began when a huge cloud of gas and particles (i.e. a nebula) collapsed under the force of its own gravity – which is known as Nebula Theory.

Explanation:

hope this helps

5 0
3 years ago
Which equation correctly relates the heat of reaction to the standard heats of formation?
VARVARA [1.3K]

Answer:

D

Explanation:

∆H° = ∆Hf ° (products) – ∆Hf ° (reactants)

4 0
3 years ago
How many carbon atoms will be in the longest chain of 2,2,4-trimethylpentane
FrozenT [24]

The carbon atoms that will be in the longest chain of 2, 2, 4 – trimethyl pentane is 5. There are 5 carbons in the longest chain that forms a cross.

<span>Hope this helps you with your question. Don’t hesitate to ask here in Brainly.</span>

6 0
3 years ago
Which of these is the BEST definition of "civilization" for a history class? A) the way people talk B) a group that has a cultur
kolbaska11 [484]
B) A group that has a culture
6 0
3 years ago
How many grams is 2 drops of food coloring?
STatiana [176]
40g! sorry if i’m wrong!!
8 0
3 years ago
Other questions:
  • Three carbon atoms are linked by single covalent bonds such that they form the shape of a v. all of the unshared electrons form
    5·1 answer
  • Compared to atoms of metals atoms of nonmetals generally have
    15·1 answer
  • tres pensamientos negativos sobre el C0Vid-19 que se vive en la actualidad y luego transformemos a pensamientos positivos.
    14·2 answers
  • Write the equilibrium constant expression, Kc, for the following reaction: Please enter the compounds in the order given in the
    10·1 answer
  • HELP !!!!!!! Please !!!!!!!
    9·1 answer
  • Most stable monatomic ion formed from fluorine
    7·1 answer
  • Given the following equation:
    11·1 answer
  • Predict whether a precipitation reaction will occur when aqueous solutions of pbcl2 and (nh4)2s
    11·1 answer
  • 2Na + 2H2O → 2NaOH+ H2<br><br> How many grams of H2 are produced if 120 g of Na react completely?
    14·1 answer
  • Which types of subatomic particles are found inside the nucleus of an atom?
    6·2 answers
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!