What is the number of nucleons in aluminium?

(a)  

Explain with examples-

(i) Atomic Number, (ii) Mass Number, (iii) Isotopes, and (iv) Isotopes

(4)

What is the gold foil experiment? Name the scientist who performed the experiment. Write the conclusions and shortcomings of Rutherford's model of an atom.

(4)

Explain why chlorine, whether as the element or its compounds, always has a relative atomic mass of about 35.5.

(3)

State two postulates of Bohr's model of an atom. Draw a diagram of Bohr's model of an atom where K and L shells are full.

(3)

Write similarities and dissimilarities between two isotopic species of an element.

(3)

Describe the essential differences between the cathode rays and the canal rays. Why are they called so?

(4)

State the postulates and the limitations of Thomson's model of an atom.

(4)

Compare the properties of Electrons, Protons and Neutrons.

(4)

Write 2 differences between cathode and canal rays. Also, define alpha particles.

(3)

Write any 2 observations which support the fact that atoms are indivisible.

Give the number of valence electrons in- $$Na^+$$

Name the sub-atomic particles which are the same in two isotopic species of an element.

(a)  

What is the valency of inert gases?

(a)  

Write the isotope used in the treatment of thyroid disorder.

(a)  

Electron configuration of magnesium is-

(a)