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.
Answer:
Lavoisier; Newlands; Moseley
Explanation:
In 1789, Antoine Lavoisier grouped the elements into gases, nonmetals, metals, and earths.
In 1865, John Newlands developed the Law of Octaves. He stated that "any given element will exhibit analogous behaviour to the eighth element following it in the table."
In 1914, Henry Moseley found a correlation between the X-ray wavelength of an element and its atomic number. He was then able to restructure the periodic table according to atomic numbers.
It is important to use low flame when evaporating water from a recovered filtrate because then the water and filtrate will not spatter and the filtrate can also be recovered after evaporating water.
If flame is not low then water as well as got spatter so it is important to use low flame so that the water and filtrate will not spatter.
Answer :
The chemists such as analytical chemists determine the structure, composition, and nature of substances by examining and identifying their various elements or compounds. These chemists are crucial to the pharmaceutical industry because pharmaceutical companies need to know the identity of compounds that they hope to turn into drugs.
Answer:
12 L of 40% sulfuric acid solution and 8 L of 10% sulfuric acid solution are needed to make 20 L of sulfuric acid solution.
Explanation:
For first solution of sulfuric acid :
C₁ = 40% , V₁ = ?
For second solution of sulfuric acid :
C₂ = 10% , V₂ = ?
For the resultant solution of sulfuric acid:
C₃ = 28% , V₃ = 20L
Also,
<u>V₁ + V₂ = V₃ = 20L</u> ......................................(1)
Using
<u>C₁V₁ + C₂V₂ = C₃V₃</u>
<u>40×V₁ + 10×V₂ = 28×20</u>
So,
40V₁ + 10V₂ = 560........................................(2)
Solving 1 and 2 as:
V₂ = 20 - V₁
Applying in 2
40V₁ + 10(20 - V₁) = 560
40V₁ + 200 - 10V₁ = 560
30V₁ = 360
<u>V₁ = 12 L</u>
So,
<u>V₂ = 20 - V₁ = 8L</u>
<u><em>12 L of 40% sulfuric acid solution and 8 L of 10% sulfuric acid solution are needed to make 20 L of sulfuric acid solution.</em></u>
