Chemistry Class 11 NCERT Solutions: Chapter 2 Structure of Atom Part 2

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Q: 3. How many neutrons and protons are there in the following nuclei?

This structure is atomic number of an element then we also know how many protons in an element

Image of Neutrons, Protons and Electron

This structure is atomic number of an element then we also know how many protons in an element

Answer:

Atomic mass = 13

Atomic number = Number of protons = 6

Number of neutrons = (Atomic mass) -(Atomic number)

Atomic mass = 16

Atomic number = 8

Number of protons = 8

Number of neutrons = (Atomic mass) (Atomic number)

Atomic mass = 24

Atomic number = Number of protons = 12

Number of neutrons = (Atomic mass) (Atomic number)

12 = 12

Atomic mass = 56

Atomic number = Number of protons = 26

Number of neutrons = (Atomic mass) (Atomic number)

26 = 30

Atomic mass = 88

Atomic number = Number of protons = 38

Number of neutrons = (Atomic mass) - (Atomic number)

Q: 4. Write the complete symbol for the atom with the given atomic number (Z) and Atomic mass (A)

(i)

(ii)

(iii)

Answer:

(i)

(iii)

Q: 5 Yellow light emitted from a sodium lamp has a wavelength Calculate the frequency and wave number of the yellow light.

Answer:

From the expression,

We get,

Where,

Wavelength of yellow light

Substituting the values in expression (i):

Thus, frequency of yellow light emitted from the sodium lamp

Wave number of yellow light,