Answer:
A) 4.3 × 10²⁴ atoms
Explanation:
Step 1: Given data
Moles of neon: 7.2 moles
Step 2: Calculate the number of atoms present in 7.2 moles of neon
In order to convert moles to toms, we need a conversion factor. In this case, we will use Avogadro's number: there are 6.02 × 10²³ neon atoms in 1 mole of neon atoms.
7.2 mol × 6.02 × 10²³ atoms/mol = 4.3 × 10²⁴ atoms
I choose the option A.
The electron absorbs energy from specific wavelength then moving from a lower energy orbital to a higher energy orbital.
Answer:
The density of the block is 2.827 grams/ cubic inch
Explanation:
The density of the block can be obtained by dividing the given mass of the block by its volume.
Density = mass / volume
The mass of the block given is 435.5 grams
The volume of the block can be obtained by using the formula:
Volume = Length X breadth X height
Volume = 3.5 X 8 X 5.5 = 154 
There fore the density will be 435.5 / 154 = 2.827 grams/ cubic inch
Answer:
9.17 g
Explanation:
1) Calculate mols of PCl5
PCl5 (aq) + 4H2O (l) ⟶ H3PO4 (aq) + 5HCl (aq)
Mass of PCl5: 26.5g
Molar Mass of PCl5 208.24g/mol
Mol of PCl5 = Mass PCl5 /Molar mass PCl5 = 26.5g / (208.24g/mol) = 0.127257011 mol
2) Calculate mols of water needed to react
Mols of H2O per 1 Mols of PCl5 = 4 (because 4 water is needed to Phosphorus pentachloride).
Mols of H2O = Mol of PCl5 * 4 = 0.127257011 * 4 = 0.509028044 mols
3) Calculate Grams of water needed to react
Mols of H2O = 0.509028044 mols
Molar Mass of H2O = 18.015 g/mol
Mass of H2O = Mols of H2O * Molar Mass of H2O
= 0.509028044 mols* 18.015 g/mol = 9.17014021 g
sf = 3
9.17 g
