Explain how a metal with one valence electron compares with a metal with more than one valence electron

The metal with one valence electron will be more reactive than a metal with more than one valence electron

Why?

To achieve stability, elements form bonds to achieve the electronic configuration of a noble gas, with completely filled valence shells.

A metal with one valence electron just needs to lose that one electron to achieve the electronic configuration of a noble gas. Let's think of Sodium. Its electronic configuration is [Ne] 3s¹. If Sodium loses that single electron to form a bond, it will achieve the electronic configuration of Neon, so it reacts violently in order to achieve stability. In contrast, metals with more than one valence electron require more energy in order to achieve the same electronic configuration.

Metals with one valence electron are called alkali metals, and are the most reactive ones.

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in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.