It can be a compound or a single element. An element is a pure substance that cannot be separated into simpler substances by chemical or physical means. There are about 117 elements, but carbon, hydrogen, nitrogen and oxygen are only a few that make up the largest portion of Earth.
hopefully that helps
Answer: option a and d
Explanation:
Option A- Benzene undergoes substitution reaction
Example : benzene reacts with chlorine to form chlorobenzene, in the presence of Iron
(iii) chloride as a catalyst
C6H6 + Cl2 ---> C6H5Cl + HCl
Option D- Benzene also undergoes addition reaction
Example: benzene reacts with hydrogen , in the presence of nickel as a catalyst to form
cyclohexane
C6H6 + 3H2 ---> C6H12
Reasons why Option B isn't the answer
Although benzeme has degree of unsaturation but it's not five degree of unsaturation.
Benzene has 6 carbon atoms and 4 degrees of unsaturation (1 ring and 3 double
bonds).
If you work backwards and double the degrees of unsaturation you have 8 degrees of
unsaturation instead of 5.
Option C - Benzene isn't a saturated hydrocarbon
It should be organized in people
Answer:
8.354 nanometers
Explanation:
To treat a diffusive process in function of time and distance we need to solve 2nd Ficks Law. This a partial differential equation, with certain condition the solution looks like this:

Where Cs is the concentration in the surface of the solid
Cx is the concentration at certain deep X
Co is the initial concentration of solute in the solid
and erf is the error function
Then we solve right side,

And we need to look up the inverse error function of 0.001964 resulting in: 0.00174055
Then we solve for x:

Answer:
Enzyme
Explanation:
An enzyme is an organic catalyst that speeds up a reaction but can be recovered unchanged.
Human lactase consists of 4092 amino acid groups and has a molar mass of about 280 000 u, so it has a complex structure.