Answer choices are:
A. potassium
B. calcium
C. aluminum
D. neon
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Correct answer choice is:
A. Potassium
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Explanation:
Potassium metal is soft and white including a silvery radiance, has a low melting point, and is a great conductor of heat and electricity. Potassium allows a bluish-red color to a blaze, and its vapor is green. Likewise, Sodium is soft sufficient to be cut with a knife. The outside is shiny and bright while opening cut but instantly transforms dull as sodium counters with oxygen in the air. The Group 1 elements, which incorporate lithium (Li), sodium (Na) and potassium (K) are similarly identified as the alkali metals. They entirely have one electron in the outer shell and so they have related characteristics.