Answer:
Explanation:
Given:
Initial mass of isotope (m₀) = 20 g
Half life of the isotope 
= (ln 4) years
The general form for the radioactive decay of a radioactive isotope is given as:
Where,
So, the equation is: 
At half-life, the mass is reduced to half of the initial value.
So, at 
. Plug in these values and solve for 'k'. This gives,
Hence, the equation for the mass remaining is given as:
Answer:Solution
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Given:u=−10cm f=20cm (convex lens)
To find: v and image's nature.
Solution: From lens formula
v
1
−
u
1
=
f
1
v
1
+
10
1
=
20
1
Explanation:
Answer:
601 nm
Explanation:
Energy of photon having wavelength of λ nm
= 
eV
Energy of 249 nm photon
=
=4.996 eV
Similarly energy of 425nm photon
=
=2.927 eV
Difference = 2.069 eV.
This energy will give rise to another photon whose wavelength will be
λ = 
= 601 nm.
Power=work/time
So,
Power =450/50=9watts
I believe the correct answer would be A. The extraction of oil shale is detrimental to the environment mainly because the process of extraction requires large amounts of land. Lands are being excavated in order to locate areas which contains the oil. This is not good since it affects ecosystems and destroy habitats.
