Answer:
No matter if you are on Earth, the moon or just chilling in space, your mass does not change. But your weight depends on the gravity force; you would weigh less on the moon than on Earth, and in space you would weigh almost nothing at all.
The mass of 165.0 g sample that remains after 90.0 minutes is 5.16 grams
calculation
lambda㏑2/18= 0.0385
m(t)= 165 x e( 0.0385 x90) =5.16g
Everything has chemical properties it depends on the reactivity and the reactivity of the other element and what form it is in
As it is located at 7s ^2 it will have 2 valence electrons that due to its position in the s orbital it will be prone to losing them to obtain a noble gas configuration.
