How are the layers of Earth's atmosphere grouped?
(A) by similarities in thermal characteristics, chemical composition,
movement, and density
(B) by differences in thermal characteristics, chemical composition,
movement, and density
(c) by similarities in thermal characteristics and chemical composition but
differences in movement and density
(D) by differences in thermal characteristics and chemical composition but
similarities in movement and density

B)

Explanation:

The layers of the atmosphere are classified by changes in temperature in accordance with height.

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms