Answer:
The mass number of an isotope is indicated in the name of the isotope by writing the name of the element followed by a hyphen and the mass number.
Explanation:
Examples include carbon-14, uranium-235, and oxygen-17.
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Answer: Molecules that are optically active due to the tetrahedral arrangement of bonds around the carbon atom are often referred to as
<u>Chiral Molecules</u>.
Explanation: Chiral molecules have stereogenic centers. When plane polarized light is fall on these compounds they rotate the light either in clockwise or anti clockwise direction. The mirror images of chiral moleculecules are non-superimposable. Below few examples for molecules containing chiral centers are given.</span>
The answer is 1.02 × 10²⁵ atoms.
1. Calculate molar mass (Mr) of P2O5 which is the sum of atomic masses (Ar) of its elements:
Ar(P) = 31 g/mol
Ar(O) = 16
Mr(P2O5) = 2 * Ar(P) + 5 * Ar(O) = 2 * 31 + 5 * 16 = 62 + 80 = 142 g/mol
2. Calculate number of moles (n) which is the quotient of a sample mass (m) and the molar mass (Mr):
n = m/Mr
m = 0.240 g
Mr = 142 g/mol
n = 0.240 / 142 = 0.0017 mol
3. Avogadro's number is the number of units atoms in 1 mole of substance:
<span>6.023 × 10²³ atoms per 1 mol
x atoms are per 0.0017 mol
</span>6.023 × 10²³ atoms : 1 mol = x atoms : 0.0017 mol
x = 6.023 × 10²³ atoms * 0.0017 mol : 1 mol
x = 0.0102 × 10²³ = 1.02 × 10² × 10²³ = 1.02 × 10²⁵ atoms
Matter cannot be created or destroyed