Questions 12-14 refer to the following aqueous solutions. (A) 1 M BaCl2 (B) 1 M HCI (C) 1 M HC H.O2 (D) 1 MNaNO (E) 1 M KOH 12. Is a basic solution 13. Has the lowest pH 14. Yield a white precipitate when added to an equal volume of 1 M NaSOslag) Questions 15-17 refer to the following elements. (A) Sodium (B) Calcium (C) Iron ,43 (D) Copper (E) Aluminum + 3 15. Occurs exclusively as M(aa) in aqueous solution 16. Forms a 2+ ion that is colorless in aqueous solution 17. Forms two common oxides of the types MO and M-O Solution Ans. #14. To yield a white precipitate with 1 M Na 2 SO 4 . Na 2 SO 4 dissociates into 2 Na + and SO 4 2- . # The salts of Na + (like NaCl from reaction of BaCl 2 and HCl) are soluble in water. Similarly Na + salt of acetic acid, KOH and Nitrates are also water soluble. That is, Na+ ion does not form a precipitate in general. # The SO 4 2- ion forms white precipitate with Ba 2+ ion, but none others in the given list. BaCl 2 (aq) + Na 2 SO 4 (aq) ----------> BaSO 4 (s) + 2 NaCl(aq) So, correct option is- 1. 1 M BaCl 2 #17. To form MO and M 2 O oxides, the element must have the oxidation numbers of +2 (in MO) and +1 (M 2 O). # Among the given list, only Cu has +1 (in CU 2 O) and +2 (CuO) oxidation numbers. So, correct option is- D. Copper. Note: Oxidation states of Fe are +2 (as Fe 2+ ) and +3 (as Fe 3+ ). .

1. Questions 12-14 refer to the following aqueous solutions. (A) 1 M BaCl2 (B) 1 M HCI (C) 1 M
HC H.O2 (D) 1 MNaNO (E) 1 M KOH 12. Is a basic solution 13. Has the lowest pH 14. Yield a
white precipitate when added to an equal volume of 1 M NaSOslag) Questions 15-17 refer to the
following elements. (A) Sodium (B) Calcium (C) Iron ,43 (D) Copper (E) Aluminum + 3 15.
Occurs exclusively as M(aa) in aqueous solution 16. Forms a 2+ ion that is colorless in aqueous
solution 17. Forms two common oxides of the types MO and M-O
Solution
Ans. #14. To yield a white precipitate with 1 M Na 2 SO 4 .
Na 2 SO 4 dissociates into 2 Na +
and SO 4
2-
.
# The salts of Na +
(like NaCl from reaction of BaCl 2 and HCl) are soluble in water. Similarly
Na +
salt of acetic acid, KOH and Nitrates are also water soluble. That is, Na+ ion does not form
a precipitate in general.
# The SO 4
2-
ion forms white precipitate with Ba 2+
ion, but none others in the given list.
BaCl 2 (aq) + Na 2 SO 4 (aq) ----------> BaSO 4 (s) + 2 NaCl(aq)
So, correct option is- 1. 1 M BaCl 2
#17. To form MO and M 2 O oxides, the element must have the oxidation numbers of +2 (in MO)
and +1 (M 2 O).
# Among the given list, only Cu has +1 (in CU 2 O) and +2 (CuO) oxidation numbers.
So, correct option is- D. Copper.
Note: Oxidation states of Fe are +2 (as Fe 2+
) and +3 (as Fe 3+
).