The SI Standard of Time Is Based On

question 30

Multiple Choice

The SI standard of time is based on:

• A)the daily rotation of the Earth
• B)the frequency of light emitted by Kr⁸⁶
• C)the yearly revolution of the Earth about the sun
• D)a precision pendulum clock
• E)none of these

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Definitions:

Oxygen

A chemical element with the symbol O, essential for respiration in most living organisms and used in various industrial processes.

Nitrogen

A diatomic gas that makes up about 78% of the Earth's atmosphere, essential for life as it is a major component of amino acids and nucleic acids.

Pressure

The force exerted per unit area upon a surface by the weight of the air above that surface in the atmosphere or by any gas in confined space.

Volume

A measurement of the amount of space an object or substance occupies.