If 150 cc of gas A contains X molecules, how many molecules of gas B will be present in 75 cc of B ? The gases A and B are under the same conditions of temperature and pressure. Name the law on which the problem is based.

According to Avogadro’s law, equal volumes of all gases under similar conditions of temperature and pressure contain an equal number of molecules. So 150 cc of B will also contain X molecules. Hence, the number of molecules present in 75 cc of B will contain X 2 molecules.

Calculate the number of moles in 12 g of oxygen gas. [ O = 16 ]

Molecular mass = 16 × 2 = 32 g 32 g of oxygen gas → 1 mole 1 g of oxygen gas → 1 32 mole Given that 12 g of oxygen gas Number of moles = 12 32 = 0 . 375 mole

E M B I B E

Selina Icse Concise Chemistry For Class 10>Chapter 5 - Mole Concept and Stoichiometry>EXERCISE-5A>Q 2

EASY

10th ICSE

IMPORTANT

Earn 100

Differentiate between $N_{2}$ and $2 N$ .

Important Questions on Mole Concept and Stoichiometry

EASY

10th ICSE

IMPORTANT

Selina Icse Concise Chemistry For Class 10>Chapter 5 - Mole Concept and Stoichiometry>EXERCISE-5A>Q 3

"The number of atoms in a certain volume of hydrogen is twice the number of atoms in the same volume of helium at the same temperature and pressure". Explain. Why?

EASY

10th ICSE

IMPORTANT

Selina Icse Concise Chemistry For Class 10>Chapter 5 - Mole Concept and Stoichiometry>EXERCISE-5A>Q 3

"When stating the volume of a gas, the pressure and temperature should also be given". Explain Why?

EASY

10th ICSE

IMPORTANT

Selina Icse Concise Chemistry For Class 10>Chapter 5 - Mole Concept and Stoichiometry>EXERCISE-5A>Q 3

Inflating balloon seems to violate Boyle's law. Explain. Why?

EASY

10th ICSE

IMPORTANT

Selina Icse Concise Chemistry For Class 10>Chapter 5 - Mole Concept and Stoichiometry>EXERCISE-5A>Q 4

Calculate the volume of oxygen at $STP$ required for the complete combustion of $100$ litres of carbon monoxide at the same temperature and pressure.

$2 CO + O_{2} \to 2 {CO}_{2}$

EASY

10th ICSE

IMPORTANT

Selina Icse Concise Chemistry For Class 10>Chapter 5 - Mole Concept and Stoichiometry>EXERCISE-5A>Q 4

$200 {cm}^{3}$ of hydrogen and $150 {cm}^{3}$ of oxygen are mixed and ignited, as per following reaction,

$2 H_{2} + O_{2} \to 2 H_{2} O$

What volume of oxygen remains unreacted ?

EASY

10th ICSE

IMPORTANT

Selina Icse Concise Chemistry For Class 10>Chapter 5 - Mole Concept and Stoichiometry>EXERCISE-5A>Q 5

24 cc

Marsh gas

({CH}_{4})

was mixed with

106 cc

oxygen and then exploded. On cooling the volume of the mixture became

82 cc

, of which,

58 cc

was unchanged oxygen. Which law does this experiment support? Explain with calculation.

EASY

10th ICSE

IMPORTANT

Selina Icse Concise Chemistry For Class 10>Chapter 5 - Mole Concept and Stoichiometry>EXERCISE-5A>Q 6

What volume of oxygen would be required to burn completely $400 ml$ of acetelyne $[C_{2} H_{2}]$ ? Also calculate the volume of carbon dioxide formed.

$2 C_{2} H_{2} + 5 O_{2} \to 4 {CO}_{2} + 2 H_{2} O (l)$