Recent questions and answers in Practical Chemistry

Formation of purple colour on the addition of sodium nitroprusside to sodium carbonate extract indicates the presence of

answered Aug 29, 2018 by akanshwall

2 answers

Lassaigne's test for the detection of nitrogen fails in

answered Nov 22, 2017 by sharmaaparna1

3 answers

Potash Alum is

answered Oct 26, 2017 by sharmaaparna1

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X and Y are two volatile liquids with molar weights of $10\; g\; mol^{–1}$ and $40\; g\; mol^{–1}$ respectively. Two cotton plugs, one soaked in X and the other soaked in Y, are simultaneously placed at the ends of a tube of length $L = 24\; cm$, as shown in the figure. The tube is filled with an inert gas at 1 atmosphere pressure and a temperature of $300\; K$. Vapours of X and Y react to form a product which is first observed at a distance d cm from the plug soaked in X. Take X and Y to have equal molecular diameters and assume ideal behaviour for the inert gas and the two vapours.The experimental value of d is found to be smaller than the estimate obtained using Graham’s law. This is due to:

answered Jan 18, 2016 by meena.p

1 answer

Identify the correct order of solubility of $Na_2S, CuS$ and $ZnS$ in aqueous solution

answered Feb 1, 2014 by mosymeow_1

1 answer

The reagent $NH_4Cl$ and aqueous $NH_3$ will precipitate

answered Feb 1, 2014 by mosymeow_1

1 answer

Potassium ferrocyanide is used in the detection of

answered Feb 1, 2014 by mosymeow_1

1 answer

A red solid is insoluble in water. However, it becomes soluble if some KI is added to water. Heating red solid in a test tube produces violet coloured fumes and droplets of metal appear on the cooler parts of test tube. The red solid is

answered Feb 1, 2014 by mosymeow_1

1 answer

Which of the following metal sulphides has maximum solubility in water?

answered Feb 1, 2014 by mosymeow_1

1 answer

When chlorine water is added to an aqueous solution of potassium halide in the presence of chloroform, a violet colour is obtained. On adding more of chlorine water, the violet colour disappears, and a colourless solution is obtained. This test confirms the presence of the following in aqueous solution.

answered Feb 1, 2014 by mosymeow_1

1 answer

Iodine reacts with $Na_2S_2O_3$ (aq) to give products which are

answered Feb 1, 2014 by mosymeow_1

1 answer

Lead has been placed in the group I and II because

answered Feb 1, 2014 by mosymeow_1

1 answer

Suspended impurities from a colloidal solution of gum in water can be removed by

answered Feb 1, 2014 by mosymeow_1

1 answer

Which of the following can be enthalpy of neutralisation of a weak acid and a strong base?

answered Feb 1, 2014 by mosymeow_1

1 answer

If enthalpy of neutralisation of $dil\; HCl$ and $NaOH\; (aq)$ is $x$ then enthalpy of neutralisation of dil HI and $Ba(OH)_2\; (aq)$ is

answered Feb 1, 2014 by mosymeow_1

1 answer

Which of the following precipitates $K^+$ from its solution?

answered Feb 1, 2014 by mosymeow_1

1 answer

Which of the following is insoluble in dil. $HNO_3$ but soluble in aqua regia?

answered Feb 1, 2014 by mosymeow_1

1 answer

When $H_2S$ is passed through an ammoniacal salt solution X, a white ppt. is obtained. Then X can be a

answered Feb 1, 2014 by mosymeow_1

1 answer

Distinguishing reagent between silver and lead salts

answered Feb 1, 2014 by mosymeow_1

1 answer

$H_2S$ in the presence of HCl precipitates group II but not group IV because

answered Feb 1, 2014 by mosymeow_1

1 answer

Concentrated nitric acid is added before proceeding to test for group III members. This is to

answered Feb 1, 2014 by mosymeow_1

1 answer

Mg is not precipitated in group V because

answered Feb 1, 2014 by mosymeow_1

1 answer

The ion that cannot be precipitated by both HCl and $H_2S$ is

answered Feb 1, 2014 by mosymeow_1

1 answer

Which of the following solution gives precipitate with $Pb(NO_3)_2$ but not with $Ba(NO_3)_2$ ?

answered Feb 1, 2014 by mosymeow_1

1 answer

An aqueous solution of salt gives white precipitate with $AgNO_3$ solution as well as with dil $H_2SO_4$. It may be

answered Feb 1, 2014 by mosymeow_1

1 answer

In a mixture having nitrite and nitrate can be destroyed by heating with

answered Feb 1, 2014 by mosymeow_1

1 answer

For the test of halides, the soda extract is acidified with

answered Feb 1, 2014 by mosymeow_1

1 answer

A salt solution is acidified with dil. $HCl$ and $BaCl_2$ solution is added. A white ppt. is formed. The salt contains

answered Feb 1, 2014 by mosymeow_1

1 answer

Which one of the following cation will give a blue coloured ash when a piece of filter paper dipped in a solution containing its salt and $Co(NO_3)_2$ is burned?

answered Feb 1, 2014 by mosymeow_1

1 answer

$H_2S$ and $SO_2$ can be distinguished by

answered Feb 1, 2014 by mosymeow_1

1 answer

Acidified $K_2Cr_2O_7$ turns green by

answered Feb 1, 2014 by mosymeow_1

1 answer

An inorganic salt when heated evolves a coloured gas which bleaches moist litmus paper. The evolved gas is

answered Feb 1, 2014 by mosymeow_1

1 answer

Heating of oxalic acid with conc. $H_2SO_4$ gives

answered Feb 1, 2014 by mosymeow_1

1 answer

A test tube containing a nitrate and another containing a bromide and $MnO_2$ are treated with conc. $H_2SO_4$. The brown fumes evolved are passed through water. The water will be coloured by

answered Feb 1, 2014 by mosymeow_1

1 answer

When a salt is heated with dil $H_2SO_4$ and $KMnO_4$ solution, the pink colour of $KMnO_4$ is discharged, the mixture contains:

answered Feb 1, 2014 by mosymeow_1

1 answer

When borax is heated in a platinum loop, the transparent bead formed contains

answered Feb 1, 2014 by mosymeow_1

1 answer

The most suitable indicator for the titrations of $Ba(OH)_2$ against HI is

answered Feb 1, 2014 by mosymeow_1

1 answer

If $pK_{in}$ of an indicator is 10.5, the pH transition range for which it is most suitable is

answered Feb 1, 2014 by mosymeow_1

1 answer

The most suitable indicator for the titration of HCOOH against NaOH is

answered Feb 1, 2014 by mosymeow_1

1 answer

Completion of diazotisation can be checked with

answered Feb 1, 2014 by mosymeow_1

1 answer

$C_6H_5OH$ and $C_2H_5OH$ can be distinguished by

answered Feb 1, 2014 by mosymeow_1

1 answer

Which of the following compound will give blood red colour while doing the Lassigne's test for N?

answered Feb 1, 2014 by mosymeow_1

1 answer

Presence of nitrogen in which of the following compound cannot be detected by Lassaigne's test?

answered Jan 30, 2014 by mosymeow_1

1 answer

Flame test is not given by

answered Jan 28, 2014 by mosymeow_1

1 answer

$[X] + H_2SO_4 \longrightarrow [Y]$ colourless with irritating smell. $[Y] + K_2Cr_2O_7 + H_2SO_4 \longrightarrow$ Green solution. [X] and [Y] are

answered Jan 28, 2014 by mosymeow_1

1 answer

The ion that cannot be precipitated by both $HCl$ and $H_2S$

answered Jan 28, 2014 by mosymeow_1

1 answer

Potassium cyanide is used for separating

answered Jan 28, 2014 by mosymeow_1

1 answer

How do we differentiate between $Fe^{3+}$ and $Cr^{3+}$ in groupIII?

answered Jan 28, 2014 by mosymeow_1

1 answer

When a substance 'A' reacts with water, it produces a combustible gas 'B' and a solution of substance 'C' in water. When another substance 'D' reacts with this solution of 'C', it also produces the same gas 'B' on warming but 'D' can produce gas 'B' on reaction with dilute sulphuric acid at room temperature. 'A' imparts a deep golden yelow colour to the smokeless flame of bunsen flame. 'A', 'B' , 'C' & 'D' are respectively

asked Jan 28, 2014 by mosymeow_1

1 answer

Three separate samples of a solution of a single salt gave these results. One formed a white ppt. with excess ammonia solution, one formed a white ppt. with dil. NaCl solution and one formed a black ppt. with $H_2S$. The salt could be:

asked Jan 28, 2014 by mosymeow_1

1 answer

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