A white precipitate obtained on adding NaOH to a Mg^2+ solution is adsorbed with the dye magneson I (p-nitrobenzene-azo-resorcinol). The observation is

a blue coloured lake adsorbed on the precipitate

a red solution with no precipitate

a yellow precipitate of the dye with magnesium

a green coloration of the supernatant liquid

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JEE Main levelSingle correct optionDifficulty 2 of 3qc125

A white precipitate obtained on adding $NaOH$ to a $Mg X^{2 +}$ solution is adsorbed with the dye magneson I (p-nitrobenzene-azo-resorcinol). The observation is

Aa blue coloured lake adsorbed on the precipitate
Ba red solution with no precipitate
Ca yellow precipitate of the dye with magnesium
Da green coloration of the supernatant liquid

Answer: A

Mg (OH) X_{2}

is precipitated in alkaline medium and adsorbs the magneson dye, giving a blue lake. The dye itself is reddish-violet in alkali, so the blue adsorbed precipitate is the positive result.

Practice Qualitative Analysis: Cations More on Group V and VI cations (Ba, Sr, Ca, Mg) and NH4+

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A white precipitate obtained on adding NaOH to a MgX2+ solution is adsorbed with the dye magneson I (p-nitrobenzene-azo-resorcinol). The observation is

Answer: A

More questions on Group V and VI cations (Ba, Sr, Ca, Mg) and NH4+

A white precipitate obtained on adding $NaOH$ to a $Mg X^{2 +}$ solution is adsorbed with the dye magneson I (p-nitrobenzene-azo-resorcinol). The observation is