Cs -137 has a half life of about 30 years. If 60 years pass, there is two half lives passed so 1/2 * 1/2= 1/4. Take 1/4 and multiply it with the mass given:
(1/4)*20mg=5mg left
        
             
        
        
        
Answer:
The Fox is at the top of the food chain; so, the other animals could increase in population and the fox could return
 
        
             
        
        
        
Answer:
The digestive system is a system where our body breaks down food to acquire important nutrients. This is the same as your local recycling center because they collect and breaks the plastic down to be reused into recycled products. 
The excretory system is a system where we remove excess unnecessary materials. This can be the same as the recycling center because they remove unnecessary materials (such as trash that is not meant to be recycled).
 
        
             
        
        
        
Answer: 6 moles of NaCl are produced when 2 moles of sodium phosphate reacts with 3 moles of  calcium chloride
Explanation:
The balanced chemical equation is:
 
  
According to stoichiometry :
2 moles of  require 3 moles of
 require 3 moles of  
Thus both are limiting reagent as both will limit the formation of product.
As 2 moles of  reacts with 3 moles of
 reacts with 3 moles of  give = 6 moles of
 give = 6 moles of 
Thus 6 moles of NaCl are produced when 2 moles of sodium phosphate reacts with 3 moles of  calcium chloride
  
 
        
             
        
        
        
Answer:
3.96 MINUTES
Explanation:
Karl likes to use cruise control when he drives on
the highway. After setting cruise control at 33.53
m/s (75 mph). At this speed, how long would it
take Karl to travel 8 kilometers?
VELOCITY = DISTANCE/TIME
OR
V=D/T
SO 
VT=D
SO
T=D/V
THE DISTANCE IS 8 KM
THE VELOCITY IS 75 MPH
THERE ARE 1.61 KM PER MILE
SO
75M[H =
75 X 1.61 KM/H =
121 KM/HR
T=D/V
T=8/121 =0.066 HOUR =
0.066 X 60 MINUTES =
3.96 MINUTES
CHECK
75 MPH =
(75 X 1.61) KM/60 MINUTES =
120,75 KM/60 MINUTES=
2.01 KM/MINUTE
to travel 8 K,M WILL TAKE
8/2.01 = 3.98 minutes