Question 1 :
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 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 4 :
In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting requisite number of electrons, then what would be the charge on the ion so formed?

Question 5 :
An element X has a mass number 4 and atomic number 2. Write the valency of this element?

Question 7 :
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 8 :
One electron is present in the outer most shell of the atom of an element X. What would be the nature of charge on the ion formed if this electron is removed from the outermost shell ?

Question 9 :
The ratio of the radii of hydrogen atom and its nucleus is ~ $10^{5}$. Assuming the atom and the nucleus to be spherical, what will be the ratio of their sizes ?

Question 10 :
Dalton’s atomic theory successfully explained: (i) Law of conservation of mass (ii) Law of constant composition (iii) Law of radioactivity (iv) Law of multiple proportion

Question 11 :
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 12 :
<img style='object-fit:contain' src='https://teachmint.storage.googleapis.com/question_assets/cbse_ncert/61b1d2b1f59b460d7261f60a.JPG' /> Which of the above in the figures do not represent Bohr's model of an atom correctly?

Question 13 :
Which of the following statements about Rutherford’s model of atom are correct? (i) considered the nucleus as positively charged (ii) established that the $\alpha$–particles are four times as heavy as a hydrogen atom (iii) can be compared to solar system (iv) was in agreement with Thomson’s model

Question 14 :
Rutherford’s 'alpha ($\alpha$) particles scattering experiment’ resulted in to discovery of _______.

Question 15 :
One electron is present in the outer most shell of the atom of an element X. What would be the value of charge on the ion formed if this electron is removed from the outermost shell ?

Question 17 :
In the Gold foil experiment of Geiger and Marsden, that paved the way for Rutherford’s model of an atom, ~ 1.00% of the $\alpha$-particles were found to deflect at angles > $50^{\circ}$. If one mole of $\alpha$-particles were bombarded on the gold foil, compute the number of $\alpha$-particles that would deflect at angles less than $50^{\circ}$.

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

Question 21 :
Which of the following is the correct electron distribution of chlorine atom ? (Atomic number of chlorine is 17).

Question 22 :
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 23 :
Which of the following scientist identified the 'Electrons' in the structure of an atom ?

Question 24 :
The number of electrons in an element X is 15 and the number of neutrons is 16. Which of the following is the correct representation of the element?

Question 25 :
An atom with 3 protons and 4 neutrons will have a valency of

Question 27 :
Rutherford’s $\alpha$–particle scattering experiment showed 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?

Question 28 :
<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 29 :
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 30 :
<img style='object-fit:contain' src='https://teachmint.storage.googleapis.com/question_assets/cbse_ncert/61b1d2b2f59b460d7261f60c.JPG' /> Find out the valency of atoms represented by the figure.