The hydrogen molecules in water keep it together
The risk of lung cancer death is no different between medium, low, and very low-tar cigarettes.
People who smoke low-tar cigarettes compensate the lack of tar by changing their breathing habits, for example, they will take deeper drags or hold the smoke in for a longer period of time, basically negating the supposed " low-tar" effect.
Answer:
years
Explanation:
Given-
Half life of 
C 
years
As we know -
Where
Mass of radioactive carbon after a time period "t"
initial mass of radioactive carbon
radioactive decay constant
time
First we will find the value of "k"
On solving, we get -
Now, when mass of 14C becomes 
% of the plant material on earth today, then its age would be
years
