Mole Concept And Stoichiometry Long Ans Concise Class-10 ICSE Chemistry Selina Solutions Chapter-5. We Provide Step by Step Answer of Long Ans Questions of Miscellaneous Exercise for ICSE Class-10. The given Solutions is according to the Latest editions. Visit official Website CISCE for detail information about ICSE Board Class-10.
Mole Concept And Stoichiometry Long Ans Concise Class-10 ICSE Chemistry Selina Solutions Chapter-5
| Board | ICSE |
| Book / Publication | Concise / Selina |
| Subject | Chemistry |
| Class | 10th |
| Writer | Dr SP Singh |
| Chapter-5 | Mole Concept And Stoichiometry |
| Topics | Long Ans (Miscellaneous Exercise) |
| Edition | 2025-2026 |
Long Ans Questions on Mole Concept And Stoichiometry
Page-97
Que-1: Give three kinds of information conveyed by the formula H2O.
Ans: Information conveyed by formula [H2O] :
- One molecule of water (H2O) is made of two atoms of Hydrogen and one atom of Oxygen.
- As atomic weight of hydrogen is 1 and that of oxygen is 16. Therefore, ratio by weight of hydrogen and oxygen is 2H/O= 2/16 = 1/8
- Molecular weight of H2O is 2H + O = 2 + 16 = 18g.
Que-2:
(a) What do you mean by stoichiometry?
(b) Define atomicity of a gas. State the atomicity of Hydrogen, Phosphorus and Sulphur.
(c) Differentiate between N2 and 2N.
Ans:
(a) Stoichiometry measures quantitative relationships, and is used to determine the amount of products/reactants that are produced/needed in a given reaction. Describing the quantitative relationships among substances as they participate in chemical reactions is known as reaction stoichiometry.
(b) Atomicity is the number of atoms in a molecule of an element.
Atomicity of hydrogen is 2, phosphorus is 4 and sulphur is 8.
(c) Difference between N2 and 2N
| N2 | 2N |
|---|---|
| It means 1 molecule of nitrogen. | It means two atoms of nitrogen. |
| It can exist independently. | It cannot exist independently. |
Que-3:
(a) What are the main applications of Avogadro’s Law?
(b) How does Avogadro’s Law explain Gay-Lussac’s Law of combining volumes?
Ans:
(a) The applications of Avogadro’s Law are:
- It explains Gay-Lussac’s law.
- It predicts atomicity of gases.
- It determines the molecular formula of gases.
- It determines the relation between molecular mass and vapour density.
- It gives the relationship between gram molecular mass and gram molar volume.
(b) According to Avogadro’s law under the same conditions of temperature and pressure, equal volumes of different gases have the same number of molecules.
H2 (1 vol. and n molecule)+ Cl2 (1 vol. and n molecule) —> 2HCl (2 vol. and 2n molecule) (by Gay-Lussac’s Law and Avogadro’s Law)
Que-4:
(a) The relative atomic mass of Cl atom is 35.5 a.m.u. Explain this statement.
(b) What is the value of Avogadro’s number ?
(c) What is the value of molar volume of a gas at S.T.P.?
Ans:
(a) The relative atomic masses of any element is the weighted average of the relative atomic masses of it’s natural isotopes. Chlorine consists of a mixture of two isotopes of masses 35 and 37 in the ratio 3 : 1.
The average relative atomic mass of Cl = {(35 x 3) + (37 x 1)}/4 = 35.5
(b) 6.022 × 1023
(c) The molar volume of a gas is 22.4 dm3 (litre) or 22400 cm3 (ml) at S.T.P.
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