For which pair of cations would the addition of dilute hydrobromic acid precipitate one but not the other?

a. Ag+ and Ca2+

The pair of cations related to the question are as below:

a. Ag+ and Ca2+

b. Hg2^2+ and Ag^+

c. Ba^2+ and Na^+

d. Ca^2+ and Ba^2+

e. Pb^2+ and Ag^+

Explanation:

a. Ag+ and Ca2+ correct

Ag+ will precipitate with dilute hydrobromic acid (HBr) but Ca+2 will not

Ag+ + Br- > AgBr (s)

Ca+2 + 2Br- > CaBr2 (aq)

B) Hg2^2+ and Ag^+ Incorrect

Both Hg2^2+ and Ag^+  will precipitate. One has to precipitate while the other does not, so this is incorrect.

C) Ba2 and Na+ both won't precipitate. Incorrect

One has to precipitate while the other does not, so this is incorrect.

D) Ca2+ and Ba 2+both won't precipitate. Incorrect

One has to precipitate while the other does not, so this is incorrect.

E ) Both Pb2 and Ag+ will precipitate. Incorrect

One has to precipitate while the other does not, so this is incorrect.

answer by yourhope:

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d. most models represent a real-world object in a simpler way.

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