JJ Thompson discovered electrons
Look at the periodic table the element next at the right of Cl is the Ar and the atomic mass is 39.948 is bigger than the Cl 35.45. All the elements after that has mases bigger than Cl.
Answer: the answer is option 3. C
Explanation:
Answer: The mass of 
molecules of phosphorus pentoxide is 20.5 g
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to the molecular mass and contains avogadro's number 
of particles.
To calculate the moles, we use the equation:
1 mole of 
weigh = 283.9 g
Thus 0.0772 moles of weigh = 
Thus the mass of molecules of phosphorus pentoxide is 20.5 g
Answer:
4.6 × 10²³ molecules:
Step-by-step solution
You will need a balanced equation with masses, moles, and molar masses, so let's gather the information in one place:
M_r: 22.99
2Na + 2H₂O ⟶ 2NaOH + H₂
m/g: 35
1. Calculate the <em>moles of Na
</em>
Moles of Na = 35 g Na × (1 mol Na/22.99 g Na)
Moles of Na = 1.52 mol Na
2. Calculate the <em>moles of H₂
</em>
Moles of H₂ = 1.52 mol Na × (1 mol H₂/2 mol Na)
Moles of H₂= 0.761 mol H₂
3. Calculate the molecules of H₂
6.022 × 10²³ molecules H₂ = 1 mol H₂
Molecules of H₂ = 0.761 × (6.022 × 10²³
/1)
Molecules of H₂ = 4.6 × 10²³ molecules H₂
The reaction forms 4.6 × 10²³ molecules of H₂.
