Download App

Chemistry [3 Mark Question Answer]

Analytical Chemistry · ICSE STD 10 (ICSE - English Medium). 20 questions.

Questions

[3 Mark Question Answer]

🎯

Test yourself on this topic

20 questions · timed · auto-graded

Question 13 Marks
Write the observation, and balanced equation for the following reaction:
A paper dipped in potassium permanganate solution is placed at the mouth of a test tube, containing sulphur dioxide gas.
View full question & answer→
Question 23 Marks
Write the observation, and balanced equation for the following reaction:
Moist starch iodide paper is placed at the mouth of a test tube containing chlorine gas.
Answer
Starch paper turns blue black:
$
2 KI + Cl _2 \longrightarrow 2 KCI + I _2
$
$I _2$ reacts with starch to give blue black colour.
The chlorine liberates iodine from $KI$ and then it is decolourised.
View full question & answer→
Question 33 Marks
Write the observation, and balanced equation for the following reaction:
Excess of ammonium hydroxide is added to a substance, obtained by adding hydrochloric acid to silver nitrate solution.
Answer
Curdy white precipitate of $AgCl$ formed by reaction between hydrochloric acid and silver nitrate solution, dissolves in excess of $NH _4 OH$.
$
AgNO _3+ HCI \longrightarrow AgCI + HNO _3
$
$
AgCI ^{+} 2 NH _4 OH \longrightarrow Ag \left( NH _3\right)_2 CI +2 H _2 O
$
View full question & answer→
Question 43 Marks
Write the observation, and balanced equation for the following reaction:
Ammonium hydroxide is added first in a small quantity, and then in excess, to a solution of copper sulphate.
Answer
When ammonium hydroxide is added in small quantity to copper sulphate solution; it gives blue precipitate of $Cu ( OH )_2$
$
\underset{\text { Blue }}{ CuSO _4}+2 NH _4 OH \longrightarrow \underset{\text { Pale blue ppt. }}{ Cu ( OH )_2}+\left( NH _4\right)_2 SO _4
$
When ammonium hydroxide is added in excess, the blue precipitate dissolves giving deep blue solution of tetra amine copper sulphate.
$
\begin{aligned}
& Cu ( OH )_2+\left( NH _4\right)_2 SO _4+2 NH _4 OH \longrightarrow \quad\left[ Cu \left( NH _3\right)_4\right] SO _4 \\
& \text { In excess } \quad \text { Tetrammine copper(II) Sulphate (Deep blue solution) } \\
&
\end{aligned}
$
View full question & answer→
Question 53 Marks
Write the observation, and balanced equation for the following reaction:
Sodium hydroxide is added dropwise to a solution of zinc sulphate, till it is in excess.
Answer
Sodium hydroxide when added to zinc sulphate gives gelatinous white precipitate which dissolves in excess of sodium hydroxide.
$
\begin{gathered}
ZnSO _4+2 NaOH \longrightarrow Zn ( OH )_2+ Na _2 SO _4 \\
Zn ( OH )_2+2 NaOH \longrightarrow Na _2 ZnO _2
\end{gathered}
$
View full question & answer→
Question 63 Marks
Copy and complete the following table which refers to the action of heat on some carbonates :
CarbonateColour of residue on cooling
Zinc carbonate
Lead carbonate
Copper carbonate
Answer
Carbonate Colour of residue on cooling
Zinc carbonate White amorphous powder
Lead carbonate Yellow
Copper carbonate Bluish green crystalline solid
View full question & answer→
Question 73 Marks
How would you distinguish between $Zn ^{2+}$ and $Pb ^{2+}$ ions, using ammonium hydroxide solution?
Answer
$Zn ^{2+}$ ions on addition of $NH _4 OH$ forms white precipitates of $Zn ( OH )_2$ which further dissolves in excess of $NH _4 OH$. On the other hand, $Pb ^{2+}$ ions do form $Pb ( OH )_2$ with ammonium hydroxides but these precipitates do not dissolve in excess of $NH _4 OH$.
View full question & answer→
Question 83 Marks
One chemical test that would enable you to distinguish between the following pair of chemicals. Describe what happens with each chemical or state no visible reaction.
Calcium nitrate solution and zinc nitrate solution.
Answer
a. $ZnNO _3+2 NaOH \longrightarrow Zn ( OH )_2+ NaNO _3$
White gelatinous ppt.
On further addi tion of $NaOH , Zn ( OH )_2$ dissolves.
b. $Ca \left( NO _3\right)_2+2 NaOH \longrightarrow Ca ( OH )_2+2 NaNO _3$
White ppt.
$Ca ( OH )_2$ precipitates are sparingly soluble in excess of sodium hydroxide.
View full question & answer→
Question 93 Marks
One chemical test that would enable you to distinguish between the following pair of chemicals. Describe what happens with each chemical or state no visible reaction.
Answer
Sodium chloride solution and sodium nitrate solution:
Add freshIy prepared ferrous suIphate solution to the two solutions. Then by the side of the test tube, pour concentrated sulphuric acid to each slowly. The one in
which brown ring appears is sodium nitrate solution while the other is sodium chIoride solution.
View full question & answer→
Question 103 Marks
How will the action of dilute hydrochloric acid on sodium carbonate and sodium sulphite enables you to distinguish between these two compounds?
Answer
$
\begin{aligned}
& \text { Sodium carbonate }+ \text { hydrochloric acid }=\text { sodium chloride }+ \text { water }+ \text { carbon dioxide } \\
& NaCO _3+ HCl \longrightarrow NaCl + H _2 O + CO _2
\end{aligned}
$Sodium sulphite + hydrochloric acid -> sodium chloride + water + hydrogen sulphide
$
2 Na _2 SO _3{ }^{+} 4 HCI \longrightarrow 4 NaCI +6 H _2 O +2 H _2 S
$
Production of Foul smelling hydrogen sulphide gas will easily help to distinguish between sodium carbonate and sodium sulphite.
View full question & answer→
Question 113 Marks
Three test tubes contain calcium nitrate solution, zinc nitrate solution and lead nitrate solution.Describe the effect of Adding ammonium hydroxide to each portion in turn till it is in excess.
Answer
Ammonium Hydroxide :
Small amountIn excess
Calcium nitrate No visible reactionNo change
Zinc nitrateWhite precipitateSoluble
Lead nitrateWhite precipitateSoluble
View full question & answer→
Question 123 Marks
Three test tubes contain calcium nitrate solution, zinc nitrate solution and lead nitrate solution.Describe the effect of Adding sodium hydroxide solution to each portion in turn till it is in excess.
Answer
Sodiurn Hydroxide :
Small amountIn excess
Calcium nitrateWhite precipitate sparingly soluble
Zinc nitrateWhite precipitateSoluble
Lead nitrate White precipitateSoluble
View full question & answer→
Question 133 Marks
What do you see when sodium hydroxide solution is added to zinc sulphate solution, till it is in excess?
Answer
When sodium hydroxide solution is added to zinc sulphate solution, till it is in excess whi te gelatinous precipi tates of $Zn ( OH ) 2$ are formed and due to the excess of sodium hydroxide these ppt. get dissolved immidiately :
$
\begin{aligned}
& ZnSO _4+2 NaOH \longrightarrow \underset{\text { white gelatinons ppt. }}{ Zn ( OH )_2+ Na _2 SO _4} \\
& Zn ( OH )_2+2 NaOH \longrightarrow \underset{\text { colourless }}{ Na _2 ZnO _2}+2 H _2 O
\end{aligned}
$
View full question & answer→
Question 143 Marks
Using sodium hydroxide solution, how will you distinguish:
Lead hydroxide from magnesium hydroxide.
Answer
Lead hydroxide from magnesium hydroxide.
When sodium hydroxide is added, lead hydroxide is dissolved in it but when sodium hydroxide is added to magnesium hydroxide, there is no visible reaction i.e. it remains insoluble.
View full question & answer→
Question 153 Marks
Using sodium hydroxide solution, how will you distinguish:
Iron (II) chloride from iron (III) chloride
Answer
Iron (II) chloride from iron (III) chloride
(i) $FeCl _2+2 NaOH \longrightarrow Fe ( OH )_2+2 NaCI$
$Fe ( OH )_2$ precipitates are dirty green gelatinous in nature.
(ii) $FeCl _3+3 NaOH \longrightarrow Fe ( OH )_3+3 NaCI$
$Fe ( OH )_3$ precipitates are reddish brown in colour.
View full question & answer→
Question 163 Marks
Using sodium hydroxide solution, how will you distinguish: Zinc nitrate solution from calcium nitrate solution

Answer
Zinc nitrate solution from calcium nitrate solution:
(i)
$
Zn \left( NO _3\right)+2 NaOH \longrightarrow Zn ( OH )_2+2 NaNO _3
$On further addition of $NaOH _4 Zn ( OH )_2$ dissolves.
(ii)
$
Ca \left( NO _3\right)_2+2 NaOH \longrightarrow Ca ( OH )_2+2 NaNO _3
$
$Ca ( OH )_2$ precipitates are sparingly soluble in excess of sodium hydroxide.
View full question & answer→
Question 173 Marks
On adding dilute ammonia solution to a colourless solution of a salt, a white gelatinous precipitate appears. This precipitate however dissolves on addition of excess of ammonia solution. Identify (Choose from Na, l, Zn, Pb, Fe)
(a) Which metal salt solution was used?
(b) What is the formula of white gelatinous precipitate obtained?
Answer
(a) Zinc ( $Zn )$ metal salt solution was used.
(b) The formula of white gelatinous precipitate is $Zn ( OH )_2$.
Concept Insight :
$
\underset{\text { Colourless }}{ ZnSO _4}+2 NH _4 OH \longrightarrow \underset{\text { White ppt. }}{ Zn ( OH )_2}+\left( NH _4\right)_2 SO _4
$
With excess of $NH _4 OH$ the oreciojtate of zinc(II) hydroxide dissolves as:
$
Zn ( OH )_2+\underset{\text { In excess }}{\left( NH _4\right)_2 SO _4+2 NH _4 OH } \longrightarrow \underset{\text { Tetrammine xinc(II)Sulphate(Colourless solution) }}{\left[ Zn \left( NH _3\right)_4\right] SO _4}+4 H _2 O
$
View full question & answer→
Question 183 Marks
What do you understand by amphoteric oxide? Give the balanced equations for the reaction with three different amphoteric oxides with a caustic alkali. Write your observation if any.
Answer
Amphoteric oxides : Amphoteric oxides are those compounds, which react with both acids and alkalis to form salt and water.
For example: Oxides of Aluminium, zinc and lead are amphoteric in nature.
Balanced equations for the reaction of different amphoteric oxides with a caustic alkali :
Amphoteric oxide + Alkali $\rightarrow$ Salt + Water
(a)
$
\underset{\text { White }}{ ZnO }+2 NaOH \longrightarrow \underset{\text { Sodium xincate(Colourless) }}{ Na _2 ZnO _2+ H _2 O }
$
(b)
$
\underset{\text { White }}{ Al _2 O _3}+2 NaOH \longrightarrow \underset{\text { Sodium sluminate(White) }}{ NaAlO _2}+2 H _2 O
$
(c)
$
\underset{\text { Yellow }}{ PbO }+2 NaOH \longrightarrow \underset{\text { Sodium plumbite(Colourless) }}{ Na _2 PbO _2+ H _2 O }
$
View full question & answer→
Question 193 Marks
Name the method used for preparation of the following salt from the list given below:
Zinc ion and Lead ion.
Answer
Zinc ion and Lead ion.
(i)
$
ZnSO _4+2 NH _4 OH \longrightarrow Zn ( OH )_2 \downarrow+\left( NH _4\right)_2 SO _4
$

$Zn ( OH ) 2$ forms white gelatinous precipitates. In the presence of excess of ammonium hydroxide these precipitates get dissolved.

(ii)
$
Pb \left( NO _3\right)_2+2 NH _4 OH \longrightarrow Pb ( OH )_2 \downarrow+2 NH _4 NO _3
$

$Pb ( OH )_2$ forms white precipitates. This precipitate is insoluble in the presence of excess of ammonium hydroxide.

Concept Insight : Ammonium hydroxide forms insoluble hydroxides when treated with certain metallic salt solution. The insoluble hydroxides thus formed get precipitated in the form of a precipitate and may be identified by their distinct colours.
View full question & answer→
Question 203 Marks
A metal whose alloy finds use in the construction of aircrafts in the powdered form is added to sodium hydroxide solution. A colourless gas was evolved and after reaction was over, the solution was colourless.
(a) Name the powdered metal added to sodium hydroxide solution.
(b) Name the gas evolved.
(c) Name the salt present in the colorless solution.
Answer
(a) The powdered metal added to sodium hydroxide solution is Aluminium.
(b) The gas evolved is hydrogen.
(c) The salt present in the colorless solution is sodium aluminate $\left.( NaAlO )_2\right)$.
Concept Insight:
The alloy of aluminium meta I i.e. duraluminium finds use in the construction of aircrafts. Reaction of aluminium metal with sodium hydroxide is as:
$
2 Al +2 NaOH +2 H _2 O \longrightarrow 2 NaAlO _2+3 H _2
$
View full question & answer→
Generate Paper FreeAll Analytical Chemistry topics