Question 2 :
Which of the following is true for an element? (i) Atomic number = number of protons + number of electrons (ii) Mass number = number of protons + number of neutrons (iii) Atomic mass = number of protons = number of neutrons (iv) Atomic number = number of protons = number of electrons.

Question 3 :
An element X has a mass number 4 and atomic number 2. Write the valency of this element?

Question 4 :
Which of the following element has an atom with one electron, one proton and no neutron ?

Question 5 :
In response to a question, a student stated that in an atom, the number of protons is greater than the number of neutrons, which in turn is greater than the number of electrons. Do you agree with the statement ? (Yes/No)

Question 7 :
In the Thomson’s model of atom, which of the following statments are correct? (i) the mass of the atom is assumed to be uniformaly distributed over the atom (ii) the positive charge is assumed to be uniformaly distributed over the atom (iii) the electrons are uniformaly distributed in the positively charged sphere (iv) the electrons attract each other to stabilise the atom.

Question 8 :
Which of the following scientist identified the 'Neutron' in the structure of an atom ?

Question 9 :
In response to a question, a student stated that in an atom, the number of protons is greater than the number of neutrons, which in turn is greater than the number of electrons. Do you agree with the statement ? (Yes/No)

Question 10 :
The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?

Question 11 :
Which of the following is the correct electron distribution of chlorine atom ? (Atomic number of chlorine is 17).

Question 12 :
The atomic number of calcium and argon are 20 and 18 respectively, but the mass number of both these elements is 40. What is the name given to such a pair of elements?

Question 13 :
An atom with 3 protons and 4 neutrons will have a valency of

Question 14 :
Which of the following scientist identified the 'Indivisibility of atoms' in the structure of an atom ?

Question 15 :
<img style='object-fit:contain' src='https://teachmint.storage.googleapis.com/question_assets/cbse_ncert/61b1d2b1f59b460d7261f60b.JPG' /> Find out the valency of atoms represented by the figure.

Question 16 :
How many electrons are there in the L shell of chlorine atom ?

Question 17 :
Which of the following scientist identified the 'Canal rays' in the structure of an atom ?

Question 18 :
Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order (i) Rutherford’s atomic model (ii) Thomson’s atomic model (iii) Bohr’s atomic model

Question 19 :
Which of the following scientist identified the 'Indivisibility of atoms' in the structure of an atom ?

Question 20 :
Which of the following scientist identified the 'Stationary orbits' in the structure of an atom ?