Answer:
The minimum number of boxes of pencils to be ordered is 630 boxes.
Explanation:
Since a pupil uses averagely 9.3 pencils
and a box contains 12 pencils,
the school enrollment is also 812
school's enrollment x average use of pencil per student
__________________________________________
number of pencils in a box
812 x 9.3 = 7551.6
7551.6 /12 = 629.3
Having a total number of 630 boxes of pencils to be ordered.
Find the hydroxide ion concentration of a solution with a pOH of 5.90. To solve this, use a scientific calculator and enter 5.90 and use the +/- button to make it negative and then press the 10x key.
Kc = [H3O+][HCO3-] / [H2CO3]
Remember that Kc is products over reactants. Also, you do not include liquid water in a Kc expression, since liquid water has no concentration.
Answer:
Answers in explanation.
Explanation:
30. A (A chemical changes changes the chemical properties)
31. C (rusting is an example of a chemical change
32. B (A reaction requires energy, so some energy will be expelled)
33. B (Color change is an example of a chemical change)
34. A (The law of the conservation of mass: Mass and Energy cannot be created nor destroyed)
Explanation:
At each reflecting surface (benzene and glass) there will be 180 degree phase change.
Now, for constructive interference the optical path in benzene is 
.
Formula to calculate thickness of a benzene thin film is as follows.
Optical path length through benzene () = 
Hence, substituting the given values into the above formula as follows.
Optical path length through benzene =
d = 
= 
= 
(as 1 nm = 
= 204.9 m
Thus, we can conclude that minimum thickness of benzene is 204.9 m.
