A radioactive sample initially contains N atoms. After three half-lives the number of atoms that have disintegrated is
A. N8
B. 3N8
C. 5N8
D. 7N8
Correct Answer: Option A
Explanation
N → N2 → N4 → N8
Introduction to Vectors and Scalars We come into contact with many physical quantities in the natural world on a daily basis. For example, things like time, mass, weight, force, and electric charge, are physical quantities with which we are all familiar. We know that time passes and physical objects have mass. Things have weight due to gravity. We exert forces when we open doors, walk along the street and kick balls. We experience electric charge directly through static shocks in winter and through using anything which runs on electricity. There are many physical quantities in nature, and we can divide them up into two broad groups called vectors and scalars. Scalars and Vectors Scalars are physical quantities which have only a number value or a size (magnitude). A scalar tells you how much of something there is. Definition: Scalar A scalar is a physical quantity that has only a magnitude (size). For example, a person buys a tub of margarine which is labelled with a mass of 500g....
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