Explanation:
25. Binary ionic compounds: They are known as the compounds which contains a cation formed from a metal and an anion formed from a non-metal or a polyatomic anion. For example : Barium sulfate
Ba : +2 ( metal of group II-A)
: -2 ( sulfate)
These two ions combine to form a binary ionic compound having formula 
Binary Molecular compounds: They are known as the compounds which contain two or more non-metals that are bonded covalently. In these compounds, no ions are present because the electrons are shared by the atoms. Examples are:
: phosphorous trichloride
: sulfur dioxide
26. The general chemical formula for an acid is HX where H is the hydrogen and X is the non-metal or polyatomic ions. Examples of acids are:
HF : Hydrofluoric acid
: Sulfuric acid
Answer:
7.1
Explanation:
equation to calculate pH is

Hmm... I'm unsure but its either B or D.
Answer:
1. Ba2+ 2. Sr2+
Explanation:
When a solution contains the Barium ,Ba²⁺ ion or Strontium, Sr²⁺ ion, they reacts with either H₂SO₄(aq) or Na₂SO₄(aq) to produce a white precipitate of BaSO₄(s) and SrSO₄(s) respectively
The chemical reactions are given below
Ba²⁺ + H₂SO₄(aq) ⇒ BaSO₄(s) + 2H⁺ (aq)
Ba²⁺ + Na₂SO₄(aq) ⇒ BaSO₄(s) + 2Na⁺ (aq)
Sr²⁺ + H₂SO₄(aq) ⇒ SrSO₄(s) + 2H⁺ (aq)
Sr²⁺ + Na₂SO₄(aq) ⇒ SrSO₄(s) + 2Na⁺ (aq)