The volume of CO₂ at STP = 2.8 L
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Further explanation
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Given
21 gram of sodium hydrogen carbonate-NaHCO₃
Required
Volume of CO₂
Solution
The decomposition of sodium bicarbonate into sodium carbonate, carbon dioxide, and water :
2 NaHCO₃(s) → Na₂CO₃(s) + CO₂(g) + H₂O(g)
mol of NaHCO₃ :
= mass : MW NaHCO₃
= 21 g : 84 g/mol
= 0.25
From the equation, mol ratio of NaHCO₃(s) :CO₂(g) = 2 : 1, so mol CO₂ :
= 1/2 x mol NaHCO₃
= 1/2 x 0.25
= 0.125
At STP, 1 mol gas = 22.4 L, so for 0.125 mol :
= 0.125 x 22.4 L
= 2.8 L
Answer : The correct option is, (4) one; five
Explanation :
Lewis-dot structure : It shows the bonding between the atoms of a molecule and it also shows the unpaired electrons present in the molecule.
In the Lewis-dot structure the valance electrons are shown by 'dot'.
The representation of valence electrons of an atom by dots around the symbol of an element is said to be the Lewis-dot symbol.
In the representation of Lewis-symbol, one electron dot must put on each side of the element symbol then paired the electrons.
As per information, element A has 1 valence electron and element B has 5 valence electrons.
Thus, the valency of A is one and B is five.
Answer:
492.6g
Explanation:
Given parameters:
Number of moles of MgSO₄.7H₂O = 2moles
Unknown:
Mass = ?
Solution:
To find the mass of this compound;
Mass = number of moles x molar mass
Molar mass of MgSO₄.7H₂O = 24.3 + 32 + 4(16) + 7[2(1) + 16]
= 246.3g/mol
Mass = 2 x 246.3 = 492.6g
1. an alpha particle
gamma rays are formally massless, positrons and electrons (beta particles) have negligible mass, but alpha particles have about 4 amu of mass