When calcium metal is placed in water, hydrogen gas bubbles out, leaving a highly alkaline (basic) solution. write the balanced chemical equation for this reaction. phases are optional. do not write an ionic equation (i. e., the answer should not show any charges).

Ca (s) + 2H₂O (l) →  Ca(OH)₂ (aq)  +  H₂ (g)

Explanation:

When solid calcium reacts with water, it produces the correspondent hydroxid and hydrogen gas.

The hydroxid which is produced, is the calcium hydroxid which is a strong base, that's why you talk about a highly alkaline solution.

Ca (s) + 2H₂O (l) →  Ca(OH)₂ (aq)  +  H₂ (g)

Calcium hydroxide is a strong base, that dissociates in water, as this:

Ca(OH)₂  →  Ca²⁺ (aq)  + 2OH⁻ (aq)

It's a basic solution,  is providing hydroxyl ions to the medium

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)