The atomic nucleus consists of which of the following pair?

Magnesium has an atomic number as 12. Find out its valency.

An element 'X' having atomic number 20 combines chemically with another element 'Y' having atomic number 8 to form a compound 'Z'. Which of the following statements are correct about the compound 'Z'?

(i) The formula of 'Z' is XY2. 

(ii) Melting point of 'Z' is very high. 

(iii) Molten form of 'Z' does not conduct electricity. 

(iv) 'Z' is soluble in water but insoluble in petrol. 

The number of electrons that can be accommodated in N shell;

Consider the following statement on Thomson's model of an atom:

1. An atom consists of a positively charged sphere and the electrons are embedded in it.

2. The negative and positive charges are not always equal in magnitude. So, the atom as a whole is not always electrically neutral.

Which of the statements given above is/are correct?

Number of valence electrons in Cl– ion are:

Rutherford's α-particle scattering experiment shows that :

(i) electrons have negative charge.

(ii) the mass and positive charge of the atom is concentrated in the nucleus.

(iii) neutron exists in the nucleus.

(iv) most of the space in atom is empty.

Which of the above statements are correct ?

What is the approximate molecular weight of common salt?

What happens when an oxygen atom becomes an oxygen ion ?

(a) It's atomic mass decreases.

(b) It's nucleon number increases.

(c) It's atomic number remains same.

(d) It's mass number increases.

Correct option is :

A thin sheet of beryllium was bombarded by α particles. This is was an famous experiment carried out by ______.