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Craziness Overload 5 years ago
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Swetha Swetha 5 years ago
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Gaurav Seth 5 years ago
Since, ni = 5
nf = 2
This transition gives rise to a spectral line in the visible region of the Balmer series.
∴ It is an emission energy.
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Gaurav Seth 5 years ago
The important property that Mendeleev used for the classification of elements was atomic weight. He arranged all known elements in the form of periodic table. Some of the elements did not fit very well if the order of atomic weight was strictly followed. For these elements, he ignored the order of atomic weight (as atomic weight measurements can be incorrect) and placed the elements with similar properties together. Thus, iodine having lower atomic weight than tellurium (of group VI) was placed in group VII along with fluorine, chlorine and bromine due to similar properties and left some gaps for undiscovered elements.
By considering the properties the adjacent elements, he predicted the properties of undiscovered elements. Later on, these elements were discovered and their properties were similar to those predicted by Mendeleev.
Thus, Mendeleev left gaps for gallium and germanium. He named these elements as eka-aluminium and eka-silicon. When these elements were discovered, their properties were similar to those predicted by Mendeleev.
Posted by Priya S T 5 years ago
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Yogita Ingle 5 years ago
Volume of carbon dioxide gas = 44.8 L
Since at STP ; 22.4 L = 1 mole of gas
=2 moles of gas.
Hence we can say that at STP; the 44.8 L of carbon dioxide gas contains 2 moles of gas. Here STP indicates the standard temperature and pressure conditions which is 22.4 L volume, at 1 atmospheric pressure and the temperature at 273 K.
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Yogita Ingle 5 years ago
1 mole of a substance is equal to its atomic mass or molecular mass expressed in grams.
The atomic mass expressed in grams is the gram atomic mass.
The molecular mass expressed in grams is the gram molecular mass.
For example
The atomic mass of sodium is 23 grams.
Therefore, 23 grams of sodium is equal to one mole of sodium atoms.
Similarly, the molecular mass of oxygen (O2) = 2 × Atomic mass of oxygen
= 2 × 16 = 32 g
So, 32 grams of oxygen is equal to one mole of oxygen molecules.
1 mole (of anything) = 6.022 × 1023 in number
Posted by Jeet Mondal 5 years ago
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Gaurav Seth 5 years ago
Mass of Compound = 42 mg = 42 x 10-3 g
6.022 x 1023 molecules of compound = 1 mole
3.01 x 1020 molecules = (3.01 x 1020 ) / (6.022 x 1023 ) = 0.5 x 10-3 moles of compound
Molar mass of the compound = Mass /No. of moles = 42 x 10-3 g / 0.5 x 10-3 = 84 g/mol
Mass of Carbon in 1 mole of Compound = 85.7/100 x 84 g/mol = 71.98 = 72 g/ mol of C
Mass of H in 1 mole = (14.3/100) x 84 = 12.012g /mol of H
No. of C atoms = 72 / 12 = 6
No. of H atoms = 12.012 /1 = 12
Therefore the formula of the compound is C6H12.
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Bhumika Sharma 5 years ago
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