An Element Found in Another Galaxy Exists as Two Isotopes

question 63

Multiple Choice

An element found in another galaxy exists as two isotopes. If 80.0 percent of the atoms have an atomic mass of 80.00 amu and the other 20.0 percent have an atomic mass of 82.00 amu, what is the atomic mass of the element?

• A)81.0 amu
• B)64.0 amu
• C)80.4 amu
• D)16.4 amu
• E)81.6 amu

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Definitions:

Secondary Circular Reactions

A developmental stage in infants from about 4 to 8 months characterized by intentional repetition of actions that produce effects on the environment.

Tertiary Circular Reactions

A stage in Piaget’s theory of cognitive development where toddlers (around 12 to 18 months) experiment with new actions to see the outcomes, demonstrating an early form of problem-solving.

Mental Representations

Internal cognitive symbols that represent external reality, which are used in the process of thinking and understanding the world.

Violation-of-Expectation

A method used in developmental psychology research to study infants' understanding of physical and social world by evaluating their reactions to surprising or unexpected events.