Verified Solution • 2025–26 Session moderate

QJEEM24Chc0f0: JEE Main 2024 Chemistry - Class 12 JEEM24Chc0f0 Solution: The number of white coloured salts, among the following is (a)…

The number of white coloured salts, among the following is

(a) SrSO4\mathrm{SrSO}_4

(b) Mg(NH4)PO4\mathrm{Mg}\left(\mathrm{NH}_4\right) \mathrm{PO}_4

(c) BaCrO4\mathrm{BaCrO}_4

(d) Mn(OH)2\mathrm{Mn}(\mathrm{OH})_2

(e) PbSO4\mathrm{PbSO}_4

(f) PbCrO4\mathrm{PbCrO}_4

(g) AgBr\mathrm{AgBr}

(h) PbI2\mathrm{PbI}_2

(i) CaC2O4\mathrm{CaC}_2 \mathrm{O}_4

(j) [Fe(OH)2(CH3COO)]\left[\mathrm{Fe}(\mathrm{OH})_2\left(\mathrm{CH}_3 \mathrm{COO}\right)\right]

Step-by-Step Verified Solution

To determine the number of white coloured salts among the listed compounds, we look at their common color characteristics:

(a) SrSO4\mathrm{SrSO}_4 - Generally, most sulfate salts are white unless the cation imparts a color. Strontium sulfate is indeed white.

(b) Mg(NH4)PO4\mathrm{Mg}\left(\mathrm{NH}_4\right)\mathrm{PO}_4 - Magnesium ammonium phosphate is also known to be white. This is typical for many phosphates with colorless cations.

(c) BaCrO4\mathrm{BaCrO}_4 - Barium chromate is well-known for its yellow color, a characteristic of many chromates.

(d) Mn(OH)2\mathrm{Mn}(\mathrm{OH})_2 - Manganese hydroxide can have a faint pink to white color, but in this context, we consider it white for counting purposes.

(e) PbSO4\mathrm{PbSO}_4 - Lead sulfate is white, consistent with many lead salts not influenced by strong coloring anions.

(f) PbCrO4\mathrm{PbCrO}_4 - Lead chromate is distinguished by its yellow color, again a feature of chromate salts.

(g) AgBr\mathrm{AgBr} - Silver bromide is known for its pale yellow to virtually white appearance, but it is more accurately described as pale yellow.

(h) PbI2\mathrm{PbI}_2 - Lead iodide exhibits a bright yellow color, typical for many iodides with heavy metal cations.

(i) CaC2O4\mathrm{CaC}_2\mathrm{O}_4 - Calcium oxalate is white, as most insoluble oxalates are.

(j) [Fe(OH)2(CH3COO)]\left[\mathrm{Fe}(\mathrm{OH})_2\left(\mathrm{CH}_3\mathrm{COO}\right)\right] - This complex containing iron is brown red due to the presence of iron ions.

Summarizing, the white salts among the given compounds are SrSO4\mathrm{SrSO}_4 , Mg(NH4)PO4\mathrm{Mg}\left(\mathrm{NH}_4\right)\mathrm{PO}_4 , Mn(OH)2\mathrm{Mn}(\mathrm{OH})_2 , PbSO4\mathrm{PbSO}_4 , and CaC2O4\mathrm{CaC}_2\mathrm{O}_4 , making a total of 5 white colored salts.

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