Bleach and anytype of cleaner like window cleaner or disinfectant is very dangerous because if you mix those two together it might cause a very deadly fume and can cause lung failure and death within about 5 hours
The mass decay rate is of the form

where
m₀ = 3000 g,the initial mass
k = the decay constant
t = time, years.
Because the half-life is 30 years, therefore

After 60 years, the mass remaining is

Answer: 750 g
Answer:
Mass is the quantity of an object.
Weight is the force with which the object is attached towards the earth.
Hope it helps