Radium and polonium is the answer to this question. I hope I helped out!
Complete question is;
Which of the following object would take you the greatest amount of force to accelerate.
A) a soccer ball with a mass of 0.5 kg
B) a refrigerator with a mass of 200 kg, C) a bike with a mass of 25 kg
D) a car with a mass of 5,000 kg,
Answer:
D) a car with a mass of 5,000 kg
Explanation:
Formula for force is;
F = ma
Where;
F is force
m is mass
a is acceleration
Now, Force is directly proportional to the acceleration and mass.
Thus, the higher the mass, the greater the force.
Thus, the object that will require the most force is the one that has the highest mass.
Looking at the options, the one with the highest mass is option D.
Answer: 
Explanation: 1 gram is equal to 1000 Milligrams so
Since you go straight across its just multiplication so 0.00200x1000=200mg
To answer it in scientific notation it should just be mg
The only stable caesium isotope is 133Cs, with 78 neutrons.
Hope this answers your Q
