Astudent took notes in class. - uses high frequency sound waves - creates images from echoes - has many applications - medical - pregnancy - kidney stones - cancer - injury identification - other - cleaning - identification of objects - breakdown of bacteria - production which would be the best title for these notes? echolocation ultrasound technology digital signal analog signal

120,630,890

step-by-step explanation:

110+10=120,620+10=630,880+10=890

- 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