Mole Concept And Stoichiometry Short Ans Concise Class-10 ICSE Chemistry Selina Solutions Chapter-5. We Provide Step by Step Answer of Short 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 Short 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 | Short Ans (Miscellaneous Exercise) |
| Edition | 2025-2026 |
Short Ans Questions on Mole Concept And Stoichiometry
Page-97
Que-1: Define or explain the terms:
(a) Vapour density,(b) Molar volume,
(c) Relative atomic mass,
(d) Relative molecular mass,
(e) Avogadro’s number,
(f) Gram atom,
(g) Mole.
Ans:
(a) Vapour density: It is defined as the ratio between the masses of equal volumes of gas (or vapour) and hydrogen under the same conditions of temperature and pressure.
(b) Molar volume: The Molar volume of a gas is the volume occupied by one gram-molecular mass or by one mole of the gas at S.T.P. It is equal to 22.4 dm3.
(c) Relative atomic mass: The Relative atomic mass of an element is the number of times one atom of the element is heavier than 1/12 times of the mass of an atom of carbon-12.
(d) Relative molecular mass: The Relative molecular mass of an element or a compound is the number that represents how many times one molecule of the substance is heavier than 1/12 of the mass of an atom of carbon-12.
(e) Avogadro’s number: Avogadro’s number is defined as the number of atoms present in 12 g (gram atomic mass) of C-12 isotope, i.e. 6.022 x1023 atoms.
(f) Gram atom: The quantity of the element which weighs equal to it’s gram atomic mass is called one gram atom of that element
(g) Mole: Mole is the amount of pure substance containing the same number of chemical units as there are atoms in exactly 12 grams of carbon-12.
Que-2: State:
(a) Gay-Lussac’s Law of combining volumes.
(b) Avogadro’s law
Ans:
(a) Gay-Lussac’s Law of combining volumes: When gases react, they do so in volumes which bear a simple ratio to one another, and to the volume of the gaseous product, provided that all the volumes are measured at the same temperature and pressure.
(b) Avogadro’s law: Avogadro’s law states that “equal volumes of all gases under similar conditions of temperature and pressure contain the same number of molecules.”
Que-3: Explain Why?
(a) “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.”
(b) “When stating the volume of a gas, the pressure and temperature should also be given.”
(c) Inflating a balloon seems to violate Boyle’s law.
Ans:
(a) Avogadro’s Law states that “equal volumes of all gases under similar conditions of temperature and pressure contain the same number of molecules.”
Considering equal volumes of hydrogen and helium,
volume of hydrogen gas = volume of helium gas
According to Avogadro’s Law:
n molecules of hydrogen = n molecules of helium gas
i.e., nH2 = nHe
1 molecule of hydrogen has 2 atoms of hydrogen and 1 molecule of helium has 1 atom of helium
∴ 2H = He
∴ atoms in hydrogen are double the atoms of helium.
(b) Since, the volume of a gas changes remarkably with change in temperature and pressure, it becomes necessary to choose standard values of temperature and pressure to which gas volumes can be referred.
(c) According to Boyle’s law, the volume of a given mass of dry gas is inversely proportional to its pressure at a constant temperature. When we inflate a balloon, the volume of air keeps increasing and at the same time the pressure of air also increases due to which balloon inflates. As pressure and volume of air increase simultaneously, hence this seems to violate Boyle’s law.
Que-4: Explain the terms empirical formula and molecular formula.
Ans: The empirical formula of a compound is the simplest formula, which gives the simplest ratio in whole numbers of atoms of different elements present in one molecule of the compound.
The molecular formula of a compound denotes the actual number of atoms of different elements present in one molecule of a compound.
—: End of Mole Concept And Stoichiometry Short Ans Concise Class-10 ICSE Chemistry Selina Solutions : –
Return to:- Concise Selina Chemistry for ICSE Class-10 Solutions
Please Share with Your Friends if Helpful
Thanks
