Given:
Half life(t^ 1/2) :30 years
A0( initial mass of the substance): 200 mg.
Now we know that
A= A0/ [2 ^ (t/√t)]
Where A is the mass that remains after t years.
A0 is the initial mass
t is the time
t^1/2 is the half life
Substituting the given values in the above equation we get
A= [200/ 2^(t/30) ] mg
Thus the mass remaining after t years is [200/ 2^(t/30) ] mg
Answer:

Explanation:
The given reactions are:
PbCl2(aq)⇌Pb2+(aq)+2Cl−(aq) 
AgCl(aq)⇌Ag+(aq)+Cl−(aq) 
Required reaction is:
PbCl2(aq)+2Ag+(aq)⇌2AgCl(aq)+Pb2+(aq)

Answer:
They are solid (with the exception of mercury, Hg, a liquid).
They are shiny, good conductors of electricity and heat.
They are ductile (they can be drawn into thin wires).
They are malleable (they can be easily hammered into very thin sheets).
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Answer:
Non metals are located on the right hand side of the periodic table with the exception of the metalloid elements boron, silicon, germanium, arsenic, tellurium, carbon, aluminum, selenium, polonium, and astatine