14
15
147.5
Answer: The sample must have passed 4 half-lives after the sample was originally formed.
Explanation: This is a type of radioactive decay and all the radioactive process follow first order kinetics.
Equation for the reaction of decay of radioisotope follows:
To calculate the initial amount of , we will require the stoichiometry of the reaction and the moles of the reactant and product.
Expression for calculating the moles is given by:
Moles of left =
Moles of
By the stoichiometry of above reaction,
1 mole of is produced by 1 mole
So, 0.7429 moles of will be produced by =
Amount of decomposed will be = 0.7429 moles
Initial amount of will be = Amount decomposed + Amount left = (0.0495 + 0.7429)moles = 0.7924 moles
Now, to calculate the number of half lives, we use the formula:
where,
a = amount of reactant left after n-half lives = 0.0495 moles
= Initial amount of the reactant = 0.7924 moles
n = number of half lives
Putting values in above equation, we get:
Taking log on both sides, we get
Answer:
4
Explanation:
Edg 2020
PLZZ
Answer:
speaker
Explanation:
speaker runs by the help of electrical energy and the magnetic energy is used and finally it is converted into sound energy
Answer:
the motor in today's standard power drills. the motor in today's standard power saws. the motor in an electric tooth brushes.
Explanation:
More axamples could be that both devices work because of electromagnetic induction, which is when a voltage is induced by a changing magnetic field.
b. False
this is a true statement
1.0 M ionic sodium chloride (NaCl)
1.0 M ionic calcium bromide (CaBr2)
1.0 M ionic aluminum bromide (AlBr3)
1.0 M ionic potassium chloride (KCl)
Answer: 1.0 M molecular sucrose (C₁₂H₂₂O₁₁).
Explanation:
1) The depression of the freezing point of a solvent when you add a solute is a colligative property.
2) Colligative properties are those physical properties of solutions that depends on the number of solute particles dissolved into the solution.
3) The relation between the number of solute particles and the depresson of the freezing point is proportional: the greater the number of solute particles the greater the freezing point depression.
4) You need to find the solution with the highest freezing point, this is the solution in which the freezing point decreased the least.
5) Then, that is the solution with least number of solute particles.
6) Since all the given solutions have the same molarity (1.0 M), you only have to deal with the possible ionization of the different solutes.
7) NaCl, CaBr₂, AlBr₃, and KCl are ionic compounds, so each unit of them will ionize into two, three, four, and two ions, respectively, while sucrose, being a covalent compound does not dissociate.
Then, 1.0 M solution of sucrose will have less solute particles than the others, and will exhitibit the lowest freezing point depression, meaning that it will have the highest freezing point of the given solutions.
Explanation:
It is known that the atomic number of sodium is 11 and its electronic distribution is 2, 8, 1.
As the number of rows (called periods) in the periodic table represent the number of shells present in an element.
Since, sodium element have only two shells. Therefore, sodium lies in row 2 of the periodic table.
Also, the elements which contain same number of valence electrons lie in the same group.
Therefore, sodium belongs to group 1 and elements of the group 1 are also known as alkali metals.
Thus, we can conclude that in the periodic table sodium lies in period 2 and group 1.