Answer:
The length is 
Explanation:
From the question we are told that
The frequencies of the two successive harmonics are
, 
The speed of sound in the air is 
Generally the frequency of a given harmonic is mathematically represented as

Here n defines the position of the harmonics
Now since the position of both harmonic is not know but we know that they successive then we can represented them mathematically as

and

So

=> 
=> 
Answer:
The number of protons in an atom is different than the atom's total mass.
Explanation:
Mendeleev had presented the first structured periodic table in 1869. But, in 1913, Henry Moseley developed the modern periodic table. The crucial difference between the two periodic tables is that Mendeleev's periodic table is generated on the basis of the atomic masses of chemical elements while the chemical element's atomic numbers were the main focus of Moseley's periodic table. There were just 56 chemical elements in Mendeleev's periodic table. On the other hand, 74 chemical elements are presented in Moseley's periodic table.