Mole Concept And Stoichiometry Very Short Ans Concise Class-10 ICSE Chemistry Selina Solutions Chapter-5. We Provide Step by Step Answer of Very 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 Very 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 | Very Short Ans (Miscellaneous Exercise) |
| Edition | 2025-2026 |
Very Short Ans Questions on Mole Concept And Stoichiometry
Page-96
Que-1: Complete the following blanks in the equation as indicated.
CaH2 (s) + 2H2O (aq) ⟶ Ca(OH)2 (s) + 2H2 (g)
(a) Moles: 1 mole + …………… ⟶ …………… + ……………
(b) Grams: 42g + …………… ⟶ …………… + ……………
(c) Molecules: 6.02 x 1023 + …………… ⟶ …………… + ……………
Ans:
(a) Moles: 1 mole + 2 mole ⟶ 1 mole + 2 mole
(b) Grams: 42g + 36g ⟶ 74g + 4g
(c) Molecules: 6.02 x 1023 + 12.04 × 1023 ⟶ 6.02 x 1023 + 12.04 × 1023
Que-2: Correct the statements, if required
(a) One mole of chlorine contains 6.023 × 1023 atoms of chlorine.
(b) Under similar conditions of temperature and pressure, two volumes of hydrogen combined with two volumes of oxygen will give two volumes of water vapour.
(c) Relative atomic mass of an element is the number of times one molecule of an element is heavier than 1/12 the mass of an atom of carbon [C12].
(d) Under the same conditions of the temperature and pressure, equal volumes of all gases contain the same number of atoms.
Ans:
(a) One mole of chlorine contains 6.022 × 1023 atoms of chlorine.
(b) Under similar conditions of temperature and pressure, four volumes of hydrogen combined with two volumes of oxygen will give two volumes of water vapour.
(c) Relative atomic mass of an element is the number of times one atom of an element is heavier than 1/12 the mass of an atom of carbon [C12].
(d) Under the same conditions of the temperature and pressure, equal volumes of all gases contain the same number of molecules.
Que-3: The gases hydrogen, oxygen, carbon dioxide, sulphur dioxide and chlorine are arranged in order of their increasing relative molecular masses. Given 8 g of each gas at S.T.P., which gas will contain the least number of molecules and which gas the most?
Ans:
According to Avogadro’s law:
Equal volumes of all gases, under similar conditions of temperature and pressure, contain equal numbers of molecules.
So, 1 mole of each gas contains = 6.02 × 1023 molecules
Mol. Mass of :
H2 = 2 g,
O2 = 32 g,
CO2 = 12 + 2(16) = 44 g,
SO2 = 32 + 2(16) = 64 g,
Cl2 = 2(35.5) = 71 g
(i) 2 g of hydrogen contains molecules = 6.02 × 1023
So, 8 g of hydrogen contains molecules
= (6.02 x 1023 )/2 x 8
= 4 × 6.02 × 1023molecules
= 24.08 × 1023molecules
(ii) 32 g of oxygen contains molecules = 6.02 × 1023
So, 8 g of oxygen contains molecules
= (6.02 x 1023 )/32 x 8
= 1.505 × 1023molecules
(iii) 44 g of carbon dioxide contains molecules = 6.02 × 1023
So, 8 g of carbon dioxide contains
= (6.02 x 1023 )/44 x 8
= 1.09 × 1023molecules
(iv) 64 g of sulphur dioxide contains molecules = 6.02 × 1023
So, 8g of sulphur dioxide contains
= (6.02 x 1023 )/64 x 8
= 0.75 × 1023molecules
(v) 71 g of chlorine contains molecules = 6.02 × 1023
So, 8g of chlorine contains
= (6.02 x 1023 )/71 x 8
= 0.67 × 1023molecules
Thus Cl2 < SO2 < CO2 < O2 < H2
(i) Least number of molecules in Cl2
(ii) Most number of molecules in H2
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