It will take 5.2 years to decay.
The half life of cobalt-60 is 5.2 years. The half life is the time taken for the mass of the substance to decrease by a half.
here, the amount of remaining substance is 50%,
so, 
n. log (0.5) = log (0.5)
n = 1
So it would take 1 half lives to decay this much, which is 1 x 5.2 which is 5.2 years.
what do you mean by radioactive decay ?
The process through which an unstable atomic nucleus loses energy via radiation is known as radioactive decay, also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration. A material that has unstable nuclei is considered as radioactive.
Learn more about decay here:-
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Answer 10
Explication nose
Answer:
When a molecule is excited to a higher state it often ends up in its lowest excited state S1 and then emits radiation.
First one is true second one is False
Answer: The capillary rise(h) in the glass tube is = 0.009m
Explanation:
Using the equation
h = 2Tcosθ/rpg
Given
Contact angle, θ = Zero
h = height of the glass tube=?
T = surface tension = 
r = radius of the tube = 0.1mm =0.0001m
p= density of ethanol = 
g= 
h = 
h= 0.09m
Therefore the capillary rise in the tube is 0.09m