This group is called “noble gases” because they do not react with other elements. This is because they have a full valence shell.
Answer:
1
The mass of the Potassium-40 is 
2
The Dose per year in Sieverts is 
Explanation:
From the question we are told that
The isotopes of potassium in the body are Potassium-39, Potassium-40, and Potassium-
41
Their abundance is 93.26%, 0.012% and 6.728%
The mass of potassium contained in human body is
per kg of the body
The mass of the first body is 
Now the mass of potassium in this body is mathematically evaluated as

substituting value


The amount of Potassium-40 present is mathematically evaluated as
0.012% * 0.024


The dose of energy absorbed per year is mathematically represented as

Where E is the energy absorbed which is given as 
Substituting value


The Dose in Sieverts is evaluated as



Answer: Tension = 53.6N
Explanation:
Given that
Height h = 1 m
Time t = 1.7 s.
Mass m = 5.1 kg
From the equation of the motion we can get the acceleration of the elevator:
h = X0+ V0t + at2/2;
Th elevator starts from rest with a constant upward acceleration. Initial velocity Vo = 0, also Xo = 0; thus
a = 2h/t2 = 2 × 1/1.7^2
a = 0.69 m/s2.
Then we can find the tension in the cord by using the formula
T = mg + ma
= 5.1 (9.8 + 0.69)
= 5.1 × 10.5
= 53.6N