Q3 of 23 Page 34

Answer the following:

Define the terms atomic number and mass number of an element.

Atomic number: The number of protons present in the nucleus of an atom is known as atomic number. It represents the number of electrons in the orbits. It is denoted by Z.


Mass number: The total number of protons and neutrons present in the nucleus of an atom is known as mass number. It is represented by the symbol A.


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Answer the following:

Why is an atom neutral in spite of the presence of charged particles in it?

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Answer the following:

List the three fundamental particles and their properties.

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Answer the following:

Define the term ‘isotope’ of an atom with a suitable example.

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Answer the following:

From the symbol 19K40. write the following


1.mass number of Potassium


2. atomic number of Potassium


3. Write the distribution of electrons in an atom of Potassium.