Answer:
The mass of water is 36 g.
Explanation:
Mass of hydrogen = 4 g
Mass of water = ?
Solution:
First of all we will write the balance chemical equation:
2H₂ + O₂ → 2H₂O
Number of moles of hydrogen = mass / molar mass
Number of moles of hydrogen = 4 g/ 2 g/mol
Number of moles of hydrogen = 2 mol
Now we compare the moles of water with hydrogen from balance chemical equation.
H₂ : H₂O
2 : 2
Mass of water = moles × molar mass
Mass of water = 2 mol × 18 g/mol
Mass of water = 36 g
If the water oxygen is in excess than mass of water would be 36 g.
Answer:
0.125 moles
Explanation:
2.8 litres is equivalent to 2.8dm³
At STP,
1 mole = 22.4 dm³
x mole = 2.8 dm³
Cross multiply
22.4x = 2.8
Divide both sides by 22.4
x = 2.8/22.4
x = 0.125
Answer :
Lewis-dot structure : It shows the bonding between the atoms of a molecule and the unpaired electrons present in the molecule.
The given molecule is, 
Beryllium has '2' valence electrons and fluorine has '7' valence electrons. Beryllium is the central atom and fluorine is the terminal atom.
Total number valence electrons in
= 2 + 2(7) = 16
According to the Lewis-dot structure, there are '4' number of bonding electrons and 12 number of non-bonding electrons (lone-pair).
The Lewis-dot structure is shown below.