If Avogadro number N A , is changed from 6.022 × 10 23 m o l - 1 to 6.022 × 10 20 m o l - 1 , this would change:

The definition of mass in units of grams

The ratio of chemical species to each other in a balanced equation.

The ratio of elements to each other in a compound.

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At equivalence point of a titration, the titrant and titrand will always have $—$

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Important Questions on Some Basic Concepts of Chemistry

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In Tollen's test for aldehyde, the overall number of electron(s) transferred to the Tollen's reagent formula

{[Ag {({NH}_{3})}_{2}]}^{+}

per aldehyde group to form silver mirror is ___.(Round off to the Nearest integer)

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

2 {KMnO}_{4} + 3 H_{2} {SO}_{4} + 5 H_{2} O_{2} \to K_{2} {SO}_{4} + 2 {MnSO}_{4} + 8 H_{2} O + 5 O_{2}

Find the nonnality of

H_{2} O_{2}

solution, if

20 mL

of it is required to react completely with

16 mL

0.02 {MKMnO}_{4}

solution. ( Molar mass of

{KMnO}_{4} = 158 g {mol}^{- 1}

)

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

0.4 g

mixture of

NaOH, {Na}_{2} {CO}_{3}

and some inert impurities was first titrated with

\frac{N}{10} HCl

using phenolphthalein as an indicator,

17.5 mL

HCl

was required at the end point. After this methyl orange was added and titrated.

1.5 mL

of same

HCl

was required for the next end point. The weight percentage of

{Na}_{2} {CO}_{3}

in the mixture is (Rounded-off to the nearest integer)

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

Given below are two statements:
Statement I : In the titration between strong acid and weak base methyl orange is suitable as an indicator.
Statement II : For titration of acetic acid with $\mathrm{NaOH}$ phenolphthalein is not a suitable indicator.
In the light of the above statements, choose the most appropriate answer from the options given below:

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

An alkali is titrated against acid with methyl orange as an indicator, which of the following is a correct combination?

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

In the given chemical reaction, colors of the ${Fe}^{2 +}$ and ${Fe}^{3 +}$ ions, are respectively :

$5 {Fe}^{2 +} + {MnO}_{4}^{-} + 8 H^{+} \to {Mn}^{2 +} + 4 H_{2} O + 5 {Fe}^{3 +}$

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

In a titration experiment, $10 mL$ of an ${FeCl}_{2}$ solution consumed $25 mL$ of a standard $K_{2} {Cr}_{2} O_{7}$ solution to reach the equivalent point. The standard $K_{2} {Cr}_{2} O_{7}$ solution is prepared by dissolving $1.225 g$ of $K_{2} {Cr}_{2} O_{7}$ in $250 mL$ water. The concentration of the ${FeCl}_{2}$ solution is closest to

[Given : molecular weight of $K_{2} {Cr}_{2} O_{7} = 294 g {mol}^{- 1}$ ]

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

The amount of sugar

(C_{12} H_{22} O_{11})

required to prepare

2 L

of its

0 .1 M

aqueous solution is:

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

The strength of an aqueous

N a O H

solution is most accurately determined by titrating: (Note: consider that an appropriate indicator is used)

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

While titration dilute

HCl

solution with aqueous

NaOH

, which of the following will not be required ?

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

2.0 g

sample containing

{MnO}_{2}

is treated with

HCl

liberating

{Cl}_{2}

. The

{Cl}_{2}

gas is passed into a solution of

KI

and

60.0 mL

0.1 {MNaS}_{2} O_{3}

is required to titrate the liberated iodine. The percentage of

{MnO}_{2}

in the sample is____. Nearest integer)
[Atomic masses (in

u

)

Mn = 55; Cl = 35.5 : O = 16, I = 127, Na = 23, K = 39, S = 32

]

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

For standardizing

NaOH

solution, which of the following is used as a primary standard?

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For kinetic study of the reaction of iodide ion with $H_{2} O_{2}$ at room temperature :

(A) Always use freshly prepared starch solution.

(B) Always keep the concentration of sodium thiosulphate solution less than that of $KI$ solution.

(D) Record the time immediately before the appearance of blue colour.

(E) Always keep the concentration of sodium thiosulphate solution more than that of $KI$ solution.

Choose the correct answer from the options given below

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

To measure the quantity of

{MnCl}_{2}

dissolved in an aqueous solution, it was completely converted to

{KMnO}_{4}

using the reaction,

{MnCl}_{2} + K_{2} S_{2} O_{8} + H_{2} O \to {KMnO}_{4} + H_{2} {SO}_{4} + HCl

(equation not balanced). Few drops of concentrated

HCl

were added to this solution and gently warmed. Further, oxalic acid

(225 mg)

) was added in portions till the colour of the permanganate ion disappeared. What is the quantity of

{MnCl}_{2}

(in mg) present in the initial solution? (Atomic weights in

g {mol}^{- 1} : Mn = 55, Cl = 35 .5

)

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

$20 mL$ of $0.02 M$ hypo solution is used for the titration of $10 mL$ of copper sulphate solution, in the presence of excess of $KI$ using starch as an indicator. The molarity of ${Cu}^{2 +}$ is found to be $_____\times 10^{- 2} M$ (nearest integer)

Given : $2 {Cu}^{2 +} + 4 I^{-} \to {Cu}_{2} I_{2} + I_{2} I_{2} + 2 S_{2} O_{3}^{- 2} \to 2 I^{—} + S_{4} O_{6}^{- 2}$

EASY

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

If Avogadro number

N_{A}

, is changed from

6.022 \times 10^{23} m o l^{- 1}

6.022 \times 10^{20} m o l^{- 1}

, this would change:

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

The number of water molecules is maximum in

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

In the titration of

I_{2} (aq)

S_{2} O_{3}^{2 -}

(aq)

using the starch indicator, the end point is indicated by:

HARD

Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

In a complexometric titration of metal ion with ligand

M (M e t a l i o n) + L (L i g a n d) \to C (C o m p l e x)

end point is estimated spectrophotometrically (through light absorption). If 'M' and 'C' do not absorb light and only 'L' absorbs then the titration plot between absorbed light

(A)

versus volume of ligand 'L'

(V)

would look like:

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Chemistry>Physical Chemistry>Some Basic Concepts of Chemistry>Mole Concept

50 mL

0 .5 M

oxalic acid is needed to neutralize

25 mL

of sodium hydroxide solution. What is the amount of

NaOH

50 mL

of the given sodium hydroxide solution?

At equivalence point of a titration, the titrant and titrand will always have —

Important Questions on Some Basic Concepts of Chemistry

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At equivalence point of a titration, the titrant and titrand will always have $—$