A sample contains 0.500 mol of aluminum. What is the mass of aluminum in the sample (in grams)?

Explanation:

To convert from moles to grams we must use the molar mass, which can be found on the Periodic Table.

Use this number as a fraction.

Multiply by the given number of moles.

The moles of aluminum will cancel.

The original number of moles, 0.500, has 3 significant figures, so our answer must have the same.

For the number we calculated, that is the tenth place. The 9 in the hundredth place tells us to round the 4 to a 5.

There are about 13.5 grams of aluminum in 0.500 moles.

13.5 g Al

Explanation:

Recall that to go from moles to mass, you multiply the amount in moles by the molar mass of the substance.

0.500 mol Al = 13.491 g Al --> 13.5 g Al (3 sig figs)

- 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

i just learnt this recently but i need to look through my notes again