Acids and Bases(MC)

請詳細解釋,其實我知ans ,但不知怎解,所以懇請各位詳細解釋,, 感激!!

1.When hydrogen chloride gas is dissolved in water,which of the following
species can be found in the resulting solution??
(1)H+
(2)Cl-
(3)OH-
A.(1) and(2)
B.(1) and(3)
C.(2) and(3)
D.(1),(2),(3) (ans) 那為何3種都有??

2.Which of the following hydroxides would react with both hydrochloric acid
and solium hydroxide??
A.Zinc hydroxide
B.Copper(II)hydroxide
C.Iron(II)hydroxide
D.Calcium hydroxide
問題:為何是那種hydroxides??

3.When sodium hydroxide solution is added into a solution of compound X,
a white ppt from.The ppt does not dissolve on the addition of excess alkali.
X may be
A.Calcium chloride
B.zinc nitrate
C.copper(II)sulphate
D.ammonium chloride
問題:為何是這答案??

4.Phosphoric acid is a tribasic acid with formula H3PO4.Which of the
following formulae represent the acid salts of Phosphoric acid ?
(1)Na3PO4
(2)KH2PO4
(3)(NH4)2HPO4
A.(1) and(2)
B.(1) and(3)
C.(2) and(3)
D. All of above
問題:為何是這答案??問題問咩??

5.Which of the following solutions when diluted will result in decreasing
conductivity but its pH value remains constant?
A.Sodium chloride solution
B.Ethanoic acid
C.Sodium hydroxide solution
D.Aqueous ammonia solution
問題:為何是這答案??問題問咩??

6.A sample of 0.09125g of hydrogen chloride is dissolved in distilled water and
made up to 250.0cm3.What is the pH value of the solution??
A.1
B.2
C.3
D.4

7.A solution has a pHvalue of 3.Which of the following conclusions can not
be deawn??
A.It liberates cabon dioxide when added to sodium carbonate solution
B.It tastes sour
C.It is a weak acid
D.It can conduct electricity

Thank a lot!!請各位詳細解釋,重點並不在ans!!!!