Question

How many grams of neon will have the same number of atoms as *8 g* of calcium ? (Atomic mass Ca = 40, Ne = 20)​

Answer 1

Answer:

2 grams of neon will contain the same number of atoms as 4 grams of calcium.

Explanation:

Answer

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i.How many grams of neon (Ne) will have the same number of a 4g

calcium (Ca)? Atomic masses : Ne= 20 u

and Ca = 40 u

ii.Calculate the molar mass of S8. (atomic mass of S =32 u

)

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Hint: Read the question properly to understand it. Number of atoms in any element is given by Na (avogadro′s number) × massatomic mass

Complete answer:

The molar mass is the mass of a given chemical element or chemical compound (g) divided by the amount of substance (mol)

In the first question, we are given the atomic masses of Ne and Ca. The question tells you that a certain number of atoms are present in 4g

of calcium, and we have to find how many grams of Ne will have those same number of atoms as in 4g

of calcium. So first we will calculate the number of atoms in calcium.

For finding the number of atoms in calcium we use the formula

Number of atoms = Na (avogadro′s number) × massatomic mass

The value of Avogadro’s number is 6.022×1023, mass and atomic masses are given in the question

Thus, Number of atoms = 6.022×1023 × 4g40g

Hence number of atoms in calcium =6.022×1022

It is said that both have the same number of atoms. So the number of atoms in neon=6.022×1022. Now we will calculate moles of Ne from number atoms by using the formula

Thus number of moles of neon =6.022×10226.022×1023

=0.1moles

Thus mass of Ne =0.1×20

=2g

Therefore 2 grams of neon will have the same number of atoms as 4 grams of calcium.

For the second question, it is given that atomic mass of S=32u

Thus molar mass of Sulphur =8×atomic mass of Sulphur

=8×32

=256g

Therefore molar mass of S8 =256g