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.

HARD

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What volume of $\frac{M}{10} {K M n O}_{4}$ must be treated with $H_{2} O_{2}$ in acidic medium to produce sufficient $O_{2}$ at STP for the complete combustion of 560 ml ${C H}_{4}$ at STP.

$M n O_{4}^{⊖} + H_{2} O_{2} + H^{\oplus} \to {M n}^{2 +} + O_{2} + H_{2} O$ (Ignoring self decomposition of $H_{2} O_{2}$ )

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Important Questions on Some Basic Concepts of Chemistry

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:

EASY

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

The amount of oxygen in

3.6

moles of water 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

EASY

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

0.023 \times 10^{22}

molecules are present in

10 g

of a substance

{}^{'}x^{'} .

The molarity of a solution containing

5 g

of substance 'x' in 2 L solution is

_________\times 10^{- 3}

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

MEDIUM

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

The first and second ionisation enthalpies of a metal are

496

and

4560 k J m o l^{- 1}

, respectively. How many moles of

H C l

and

H_{2} S O_{4},

respectively, will be needed to react completely with

1

mole of the metal hydroxide?

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:

EASY

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

Calculate the number of sulphate ions present in

100 ml

0.001 M H_{2} {SO}_{4} ?

MEDIUM

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

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

Which one of the followings has maximum number of atoms?

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:

EASY

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

One mole of carbon atom weighs

12 g

, the number of atoms in it is equal to, (Mass of carbon

- 12

1.9926 \times 10^{- 23} g)

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

MEDIUM

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

Which of the following has the largest number of moles?

EASY

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

How many moles of electrons will weigh one kilogram ?

EASY

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

Calculate the mass of

AgCl

precipitated, when

25 ml

35 %

solution of

{AgNO}_{3}

and

25 ml

11.6 %

solution of

NaCl

are mixed is

EASY

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

An amount of

18 g

glucose corresponds to:

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

The number of water molecules is maximum in

What volume of M10 KMnO4 must be treated with H2O2 in acidic medium to produce sufficient O2 at STP for the complete combustion of 560 ml CH4 at STP. MnO4⊖+H2O2+H⊕→Mn2++O2+H2O (Ignoring self decomposition of H2O2 )

Important Questions on Some Basic Concepts of Chemistry

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