Question

when china rose indicater is added to a solution of washing soda , it's colour will change to
A) dark pink
B) red
C) green
D) yellow​

Answer 1

$\large{\underline{\underline{\red{\tt{\purple{\leadsto } AnsweR:-}}}}}$

Firstly we know that Washing soda is basic in nature that is in aqueous solution it liberates $\sf OH^{-}$ ions . Now china rose indicator shows following changes in acidic or basic medium .

• In acidic medium it changes to dark pink.
• In basic medium it changes to green.
• No change for neutral solutions.

So , due to basic behaviour of washing soda it will turn out to be $\sf{\green{ green }}$

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$\large{\underline{\underline{\red{\tt{\purple{\leadsto } RelateD\:\: Information:-}}}}}$

$\bf{\purple{\qquad\qquad\qquad \orange{\dag} ACID }}$

Acids are generally those substances which have a sour taste . They change the colour of blue litmus to red. according to Arrhenius concept an acid is a substance which which contains hydrogen ions and produces H + ions in its aqueous solution according to Bronsted Lowry theory and acid is a substance that is a H + Ion donor.

$\tt \green{ Example - \pink{HCl,H_2SO_4,etc}}$

$\bf{\purple{\qquad\qquad\qquad \orange{\dag} BASE }}$

Bases are generally those substances which have a bitter taste change the colour of red litmus to blue. According to our Arrhenius concept and space is a substance which contains Hydroxyl ions ( OH$^{-1}$) and produces hydroxyl ions in its aqueous solution. according to Bronsted lowry theory a base is a substance that is a H + Ion acceptor .

$\tt \green{ Example - \pink{Mg(OH)_2,NaOH,etc}}$

$\bf{\purple{\qquad\qquad\qquad \orange{\dag} INDICATORS }}$

Indicators are chemicals which change their colour in the presence of acid or base . It may be natural or synthetic. Universal indicator is a mixture of several indicators and is required in required for proportions which show colour changes over considerable pH range.

Here are some indicators and their color change in acidic and basic medium.

$\boxed{\begin{tabular}{|c|c|c|}\cline{1-3} \bf Indicator &\bf Acid&\bf Base\\\cline{1-3} \sf Litmus Solution & Blue to Red & Red to Blue \\\cline{1-3} \sf Phenolphthalein & Remains colourless & Changes to pink \\\cline{1-3} \sf Turmeric & Remains yellow & Reddish brown \\\cline{1-3}\sf Methyl Orange & Red & yellow \\\cline{1-3} \sf China Rose & Magenta & green\\\cline{1-3} \end{tabular}}$