Answer:
A mole is the amount of pure substance containing the same number of chemical units as there are atoms in exactly
12 grams of carbon-12 (i.e., 6.023 X 1023).
Explanation:
Answer : The mass of the water molecule is 4.5 times greater than the mass of the helium atom.
Explanation :
Assumption : The number of water molecules is equal to the number of helium atoms
Given : The mass of water = 4.5 × The mass of helium ........(1)
The mass of Water = Mass of 1 water molecule × Number of water molecule
The mass of Helium = Mass of 1 helium atom × Number of helium atom
Now these two masses expression put in the equation (1), we get
Mass of 1 water molecule × Number of water molecule = 4.5 × Mass of 1 helium atom × Number of helium atom
As per assumption, the number of water molecules is equal to the number of helium atoms. The relation between the mass of water molecule and the mass of helium atom is,
Mass of water molecule = 4.5 × Mass of helium atom
Therefore, the mass of the water molecule is 4.5 times greater than the mass of the helium atom.
It’s mass number would be 5 as it’s the protons and the neutrons added together
Answer:
0.302 moles
Explanation:
Data given
Mass of Pb(NO₃)₂ = 100 g
Moles of Pb(NO₃)₂ = ?
Solution:
To find mole we have to know about molar mass of Pb(NO₃)₂
So,
Molar mass of Pb(NO₃)₂ = 207 + 2[14 + 3(16)]
= 207 + 2[14 + 48]
= 207 + 124
Molar mass of Pb(NO₃)₂ = 331 g/mol
Formula used :
no. of moles = mass in grams / molar mass
Put values in above formula
no. of moles = 100 g / 331 g/mol
no. of moles = 0.302 moles
no. of moles of Pb(NO₃)₂ = 0.302 moles
