Explanation:
Use the density formula to determine the volume of the piece of metal.
density
=
mass
volume
Rearrange the equation to isolate volume.
volume
=
mass
density
volume
=
147
g
7.00
g
mL
=
21.0 mL
The final volume in the cylinder after adding the piece of metal is
20.0 mL
+
21.0 mL
=
41.0 mL
Explanation:
Elements need a total of eight electrons to gain stability and look like a noble gas. So, they sometimes need sharing of two, four or even six electrons to complete their octate. So, they form double and triple covalent bonds. One more the reason is the interaction between the p orbitals of the combining atoms. for example A double bond, as in ethene H2C=CH2, arises from one combination of the s orbitals and one combination of the p_y orbitals.
Given, half life of a certain radioactive element = 800 years.
Amount of substance remaining at time t = 12.5%
Lets consider the initial amount of the radioactive substance = 100%
Using the half life equation:
A = A₀(1/2)^t/t₁/₂
where A₀ is the amount of radioactive substance at time zero and A is the amount of radioactive substance at time t, and t₁/₂ is the half-life of the radioactive substance.
Plugging the given data into the half life equation we have,
12.5 = 100 . (1/2)^t/800
12.5/100 = (1/2)^t/800
0.125 = (0.5)^t/800
(0.5)^3 = (0.5)^t/800
3 = t/800
t = 2400 years
Thus the object is 2400 years old.
