Answer: (E) 300 bq
Explanation:
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
Radioactive decay process is a type of process in which a less stable nuclei decomposes to a stable nuclei by releasing some radiations or particles like alpha, beta particles or gamma-radiations. The radioactive decay follows first order kinetics.
Half life is represented by 
Half life of Thallium-208 = 3.053 min
Thus after 9 minutes , three half lives will be passed, after ist half life, the activity would be reduced to half of original i.e. 
, after second half life, the activity would be reduced to half of 1200 i.e. 
, and after third half life, the activity would be reduced to half of 600 i.e. 
,
Thus the activity 9 minutes later is 300 bq.
the answer of these question is weight
Answer: varriable
Explanation:meaning one element, feature or factor able to change
Answer:
Mass = 12.276 g
Explanation:
Given data:
Number of molecules of H₂S = 2.16 × 10²³
Mass in gram = ?
Solution:
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
18 g of water = 1 mole = 6.022 × 10²³ molecules of water
Number of moles of H₂S:
2.16 × 10²³ molecules × 1 mole /6.022 × 10²³ molecules
0.36 moles
Mass = number of moles × molar mass
Mass = 0.36 mol × 34.1 g/mol
Mass = 12.276 g
