Which of the following compounds contains covalent bonds? * Cs₂O Fe₂O₃ NaCl CCl₄
1 answer:
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Answer : The correct answer is 96.68 yrs
Radioactivity Decay :
it is a process in which a nucleus of unstable atom emit energy in form of radiations like alpha particle , beta particle etc .
Radioactive decay follows first order kinetics , so its rate , rate constant , amount o isotopes can be calculated using first order equations .
The first order equation for radioactive decay can be expressed as :
----------- equation (1)
Where : N = amount of radioisotope after time "t"
N₀ = Initial amount of radioisotope
k = decay constant and t = time
Following steps can be used to find time :
1) To find deacy constant :
Decay constant can be calculated using half life . Decay constant and half life can be related as :
---------equation (2)
Given : Half life of Strontium -90 = 28.8 years
Plugging value of in above formula (equation 2) :
Multiply both side by k
Dividing both side by 28.8 yrs
(ln 2 = 0.693 )
k = 0.0241 yrs⁻¹
Step 2 : To find time :
Given : N₀ = 10.3 ppm N = 1.0 ppm k = 0.0241 yrs⁻¹
Plugging these value in equation (1) as :
(ln 0.0971 = - 2.33 )
Dividing both side by - 0.0241 yrs⁻¹
t = 96.68 yrs
Hence the concentration of Strontium-90 will drop from 10.3 ppm to 1.0 ppm is 96.68 yrs
The heat lost is
The heat lost when the ice is cooled from 400k to 263K can be calculated using the formula of heat transfer.
<h3>Heat Transfer</h3>This is the heat transferred from a body of higher temperature to a body of lower temperature.
- Q = Heat Transfer
- m = mass = 1277g
- ΔT = change in temperature
We converted the temperature from kelvin scale into Celsius scale and find the change in temperature.
Solving for heat transfer
The heat loss is approximately
Learn more on heat transfer here;