Machines can be classified into two categories: Simple and Compound
A simple machine is a basic device used for applying a force to produce a certain outcome. for example: lever, wedge, inclined plane are all simple machines.
A compound machine is a combination of simple machines.
In the given example: Shovel is a compound machine which is a combination of wedge and lever.
The reaction of sodium sulfide with hydrogen sulfide can be shown as
Sodium hydroxide is completely reacting and thus act as limiting reactant
Thus, 2.31 g Na2S produced.
Fe + heat ----> Fe_54 + + neutrons
T=20 min
m₀=200 g
t=60 min
the mass of element through time t is:
m=m₀*2^(-t/T)
m=200*2^(-60/20)=25 g
25 grams of element will be left after 60 minutes