An element has two isotopes, A and B, with mass numbers of 32.0 and 33.0 respectively. The relative atomic mass is 32.3. The percentage abundance of the two isotopes is: a) A - 20% B - 80%

b) A - 25% B - 75%

c) A - 80% B - 20%

d) A - 70% B - 30%

e) A - 50% B - 50%

d) A - 70% B - 30%

Explanation:

If x is the abundance of A, and 1−x is the abundance of B, then:

x (32.0) + (1−x) (33.0) = 32.3

32x + 33 − 33x = 32.3

33 − x = 32.3

x = 0.7

The abundance of A is 70%, and the abundance of B is 30%.

- 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

a  solution  is always transparent, light passes through with no scattering from solute particles which are molecule in size. the  solution  is homogeneous and does not settle out. a colloid is intermediate between asolution  and a  suspension. while asuspension  will separate out a colloid will not.