5 moles of A B 2 weigh 125 × 10 - 3 k g and 10 moles of A 2 B 2 weigh 300 × 10 - 3 k g . The molar mass of A ( M A ) and molar mass of B ( M B ) in k g m o l - 1 are:

M A = 5 × 10 - 3 and M B = 10 × 10 - 3

M A = 25 × 10 - 3 and M B = 50 × 10 - 3

M A = 50 × 10 - 3 and M B = 25 × 10 - 3

M A = 10 × 10 - 3 and M B = 5 × 10 - 3

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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The mass of $P_{4} O_{10}$ produced if $440 gm$ of $P_{4} S_{3}$ is mixed with $384 gm$ of $O_{2}$ is $P_{4} S_{3} + O_{2} ⟶ P_{4} O_{10} + {SO}_{2}$

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Important Questions on Some Basic Concepts of Chemistry

EASY

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

An amount of

18 g

glucose corresponds to:

EASY

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

The percentage of nitrogen by mass in ammonium sulphate is closest to (atomic masses H = 1, N = 14, O = 16, S = 32)

EASY

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

Mass % of carbon in ethanol is

EASY

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

The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1 : 4. The ratio of number of their molecules is:

MEDIUM

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

A sample of a hydrate of barium chloride weighing 61 g was heated until all the water of hydration is removed. The dried sample weighed 52 g. The formula of the hydrated salt is: (atomic mass, Ba = 137 amu, Cl = 35.5 amu)

EASY

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

The amount of oxygen in

3.6

moles of water is:

EASY

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

The volume of oxygen at STP required to burn 2.4 g of carbon completely is:

EASY

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

The percentage composition of carbon by mole in methane is:

MEDIUM

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

A mixture of gases contains

H_{2}

and

O_{2}

gases in the ratio of

1 : 4

(w/w). What is the molar ratio of the two gases in the mixture?

EASY

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

Suppose the elements

X

and

Y

combine to form two compounds

X Y_{2}

and

X_{3} Y_{2}

. When

0.1 mole

X Y_{2}

weighs

10 g

and

0.05 mole

X_{3} Y_{2}

weighs

9 g

, the atomic weights of

X

and

Y

are

HARD

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

The ratio of mass percent of

C and H

of an organic compound

(C_{X} H_{Y} O_{Z})

6 : 1 .

If one molecule of the above compound

(C_{X} H_{Y} O_{Z})

contains half as much oxygen as required to burn one molecule of compound

C_{X} H_{Y}

completely to

{CO}_{2}

and

H_{2} O .

The empirical formula of the compound

C_{X} H_{Y} O_{Z}

EASY

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

The number of water molecules is maximum in

HARD

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

An organic compound contains

C, H

and

S

. The minimum molecular weight of the compound containing

8 %

Sulphur is

EASY

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

A compound has the following composition by weight;

N a = 18.60 %, S = 25.80 %, H = 4.02 %

and

O = 51.58 %

Assuming that all the hydrogen atoms in the compound are part of water of crystallization, the correct molecular formula of the compound is

MEDIUM

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

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve

10 p p m

of iron in

100 k g

of wheat is ____________. (Up to two decimal place)
Atomic weight:

F e = 55.85; S = 32.00; O = 16.00

MEDIUM

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

The flocculation value of

H C l

for arsenic sulphide

s o l

30 m m o l L^{- 1}

. If

H_{2} S O_{4}

is used for the flocculation of arsenic sulphide, the amount, in grams, of

H_{2} S O_{4}

250 m l

required for the above purpose is ________. (Round off to two digits after decimal.)
(molecular mass of

H_{2} {S O}_{4} = 98 g / m o l

EASY

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

5

moles of

A B_{2}

weigh

125 \times 10^{- 3} k g

and

10

moles of

A_{2} B_{2}

weigh

300 \times 10^{- 3} k g

. The molar mass of A

(M_{A})

and molar mass of

B (M_{B})

k g {m o l}^{- 1}

are:

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

An unknown chlorohydrocarbon has 3.55 % of chlorine. If each molecule of the hydrocarbon has one chlorine atom only; chlorine atoms present in 1 g of chlorohydrocarbon are :(Atomic wt. of

Cl = 35 .5 u;

Avogadro constant

= 6 .023 \times 10^{23} {mol}^{- 1}

)

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:

HARD

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

In Carius method of estimation of halogens,

250 mg

of an organic compound gave

141 mg AgBr

. What is the percentage of bromine in the compound (atomic mass of

Ag = 108

and atomic number of

Br = 80

The mass of P4O10 produced if 440 gm of P4 S3 is mixed with 384 gm of O2 is P4 S3+O2⟶P4O10+SO2

Important Questions on Some Basic Concepts of Chemistry

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The mass of $P_{4} O_{10}$ produced if $440 gm$ of $P_{4} S_{3}$ is mixed with $384 gm$ of $O_{2}$ is $P_{4} S_{3} + O_{2} ⟶ P_{4} O_{10} + {SO}_{2}$