Answer:
Elements having same valence electrons are placed in <u>same group.</u>
Explanation:
First, let's start with some basic concepts of modern periodic table:
1. Modern Periodic table : It is the arrangement of element in the increasing order of their atomic numbers
The Modern periodic table is divided into Periods and groups .
Periods : These are the horizontal rows. There are seven periods in the periodic table . Period 1 has 2 element. Period two and three has 8 elements , period 4 and 5 have 18 elements and the period 6 and 7 have 32 elements.
Same period have same number of atomic orbital(Shell)
Group : The group is the vertical columns . There are 18 groups in the modern periodic table.Those element which have same group number will also have same number of electron in their outermost shell. The number of electron in the outermost shell determines the valency of the element.
So, elements showing same valency are placed in same group.
All alkali are place in group 1 and have 1 valance electron in the outermost shell
2BF₃ + 3Li₂SO₃ ----> B₂(SO₃)₃ + <u>6LiF
</u>:)<u>
</u>
Answer:
0.35 atm
Explanation:
It seems the question is incomplete. But an internet search shows me these values for the question:
" At a certain temperature the vapor pressure of pure thiophene (C₄H₄S) is measured to be 0.60 atm. Suppose a solution is prepared by mixing 137. g of thiophene and 111. g of heptane (C₇H₁₆). Calculate the partial pressure of thiophene vapor above this solution. Be sure your answer has the correct number of significant digits. Note for advanced students: you may assume the solution is ideal."
Keep in mind that if the values in your question are different, your answer will be different too. <em>However the methodology will remain the same.</em>
First we <u>calculate the moles of thiophene and heptane</u>, using their molar mass:
- 137 g thiophene ÷ 84.14 g/mol = 1.63 moles thiophene
- 111 g heptane ÷ 100 g/mol = 1.11 moles heptane
Total number of moles = 1.63 + 1.11 = 2.74 moles
The<u> mole fraction of thiophene</u> is:
Finally, the <u>partial pressure of thiophene vapor is</u>:
Partial pressure = Mole Fraction * Vapor pressure of Pure Thiophene
- Partial Pressure = 0.59 * 0.60 atm
Answer:
28500 years
Explanation:
Applying,
A = A'(
)............... Equation 1
Where A = Original mass of Carbon-14, A' = Final mass of carbon-14 after decaying, x = total time, y = half-life.
From the question,
Given: A = 1 g, A' = 31.3 mg = 0.0313 g, y = 5700 years.
Substitute these values into equation 1
1 = 0.0313(
)
= 1/0.0313
= 31.95
≈ 32
≈ 2⁵
Equating the base and solve for x
x/5700 ≈ 5
x ≈ 5×5700
x ≈ 28500 years
This problem is providing the mass, energy, initial temperature and specific heat of a sample of copper that is required to calculate the final temperature.
Thus, we recall the general heat equation:
Which has to be solved for the final temperature, 
as follows:
Finally, we plug in the numbers to obtain:
However, this result is not given in the choices.
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