What is the molarity of a hydrochloric acid solution, when 30.0 mL is neutralized by 48.0 mL of 0.100 mol/L calcium hydroxide?

The molarity of a hydrochloric acid solution : 0.32 M

Titration is a procedure for determining the concentration of a solution by reacting with another solution which is known to be concentrated (usually a standard solution).

Titrations can be distinguished including acid-base titration, depositional titration, and redox titration. An acid-base titration is the principle of neutralization of acids and bases is used.  

Acid-base titration formula  

Ma. Va. na = Mb. Vb. nb  

Ma, Mb = acid base concentration  

Va, Vb = acid base volume  

na, nb = acid base valence  

1 ⇒HCl (valence=1, HCl ⇒H⁺+Cl⁻, one H⁺)

2⇒Ca(OH)₂(valence=2, Ca(OH)₂⇒Ca²⁺+2OH⁻, two OH⁻)

M₂=0.1 M

V₂=48 ml=0.048 L

V₁=30 ml=0.03 L

indium, and thallium have three electrons i think

tracks, burrows, eggshells, nests, tooth marks, or gastroliths