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प्रश्न
Explain with examples what is meant by a 'mole' of a substance.
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उत्तर
A mole is the quantity of a substance whose mass in grams is equal in magnitude to the molecular mass of that substance in Daltons. Thus, the molecular mass of oxygen is 32 u, and therefore 32g oxygen is 1 mole of oxygen. The molecular mass of water is 18u. Therefore, 18g of water makes 1 mole of water.
1 mole of a compound is the mass of that substance in grams equal in magnitude to its molecular mass. The SI unit is mol.
Number of moles of substances (n) = `"Mass of substance in grams"/"Molecular mass of substance"`
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संबंधित प्रश्न
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Ethyne, C2H2
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Fill in the following blanks :
60 g of carbon element are .............. moles of carbon atoms.
Calculate the mole ratio of 240 g of calcium and 240 g of magnesium. (Ca = 40 u ; Mg = 24 u)
Define the term.
Molar volume
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[Avogadro’s number = 6 × 1023, O = 16 ]
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NH4NO3 → N2O + 2H2O
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Define the term:
Relative molecular mass
Calculate the number of moles of methane in 0.80 g of methane.
Calculate the mass of 0.1 mole of the following:
CaCl2
(Ca = 40, Na=23, Mg =24, S=32, C = 12, Cl = 35.5, O=16, H=1)
Calculate the mass of 0.1 mole of the following:
Mg
(Ca = 40, Na = 23, Mg = 24, S = 32, C = 12, Cl = 35.5, O = 16, H = 1)
Calculate the number of atoms in the following:
52 g of He
Which of the following weighs the least?
How many grams are there in the following?
4 moles of the phosphorous molecule, P4
Fill in the missing data in the Table
| Species Property | H2O | CO2 | Na atom | MgCl2 |
| No. of moles | 2 | - | - | 0.5 |
| No. of particles | - | 3.011×1023 | - | - |
| Mass | 36g | - | 115 g | - |
Compute the difference in masses of 103 moles each of magnesium atoms and magnesium ions.
(Mass of an electron = 9.1×10–31 kg)
The number of atoms present in 0.1 mole of P4 (at. mass = 31) is ______.
