You start with 4800 grams uranium - 238. It's radioactive and goes through alpha decay. How many grams remain after 7 half-lives.

37.5g

Explanation:

The half-life is the time taken for a radioactive substance to decay to half its original composition;

 Original composition here is  = 4800g  of U-238

How many grams remain after 7 half-lives;

 After each life, the uranium reduces by half;

 Amount remaining  = 4800 x  

                                  = 37.5g

After 7 half lives, 37.5g of the original sample will remain.

- 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

pie chart because it is in percents ( % )