An alkali is titrated against an acid with methyl orange as indicator, which of the following is a correct combination?

Options

A. `{:("Base",,"Acid",,"End point"),("Weak",,"Strong",,"Yellow to pinkish red"):}`
B. `{:("Base",,"Acid",,"End point"),("Strong",,"Strong",,"Pink to clourless"):}`
C. `{:("Base",,"Acid",,"End point"),("Weak",,"Strong",,"Colourless to pink"):}`
D. `{:("Base",,"Acid",,"End point"),("Strong",,"Strong",,"Pinkish red to yellow"):}`

Answer

A

Explanation

`underset("Weak base")(NH_(4)OH)+underset("Strong acid")(HCl) to NH_(4)Cl+H_(2)O`
At end point pH will be less than 7
As strong acid weak base salt have
`pH=7-((pK_(b)+logc))/(2)`
`:.` Methyl orange will change colour from yellow to pinkish red at the end point.