Which example does not involve knowledge of chemistry? a. a firefighter working to put out a fire b. a photographer developing color film c. an astronomer identifying the stars of a constellation d. a medical student learning how drugs work

I would honestly say C. All others have ingredients in them that makes them work, the combination of stuff to put out the fire, film is made from a certain material and drugs are an ovbious mixture. Looking at the stars is the only thing you don't need chemistry for.

sry but any answer choices

- 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