The quantity of substance remains after 850 years is 8.98g if the half life of radioactive radium is 1,599 years.
<h3>What is half life period? </h3>
The time taken by substance to reduce to its half of its initial concentration is called half life period.
We will use the half- life equation N(t)
N e^{(-0.693t) /t½}
Where,
N is the initial sample
t½ is the half life time period of the substance
t2 is the time in years.
N(t) is the reminder quantity after t years .
Given
N = 13g
t = 350 years
t½ = 1599 years
By substituting all the value, we get
N(t) = 13e^(0.693 × 50) / (1599)
= 13e^(- 0.368386)
= 13 × 0.691
= 8.98
Thus, we calculated that the quantity of substance remains after 850 years is 8.98g if the half life of radioactive radium is 1,599 years.
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Velocity = 15 m/s
90/2 = 45 m
45/3 (seconds to reach) = 15 m
Answer:
C. fluorine (F) and chlorine (Cl)
D. arsenic (As) and antimony (Sb)
Explanation:
In the periodic table , all the elements are arranged according to the atomic number ,
and the elements are placed in groups and periods ,
The elements with similar chemical and physical properties are placed in a common group .
The elements present in the same group have the same number of valence electrons in the valence shell .
Hence , from the given options ,
fluorine (F) and chlorine (Cl) belongs to group 17 with 7 valence electrons in the outermost shell .
arsenic (As) and antimony (Sb) belong to group 15 with 3 valence electrons in the outermost shell .
Answer:- Frequency is 
.
Solution:- frequency and wavelength are inversely proportional to each other and the equation used is:
where, 
is frequency, c is speed of light and 
is the wavelength.
Speed of light is 
.
We need to convert the wavelength from nm to m.
( 
)
= 
Now, let's plug in the values in the equation to calculate the frequency:
= 
or
since, 
So, the frequency of the green light photon is .
