Question 2 :
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 3 :
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 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 6 :
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 7 :
In a sample of ethyl ethanoate ($CH_{3}COOC_{2}H_{5}$) the two oxygen atoms have the same number of electrons but different number of neutrons. Which of the following is the correct reason for it?
Question 9 :
Which of the following scientist identified the 'Electrons' in the structure of an atom ?
Question 12 :
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 14 :
Which of the following scientist identified the 'Concept of nucleus' in the structure of an atom ?
Question 15 :
Rutherford’s 'alpha ($\alpha$) particles scattering experiment’ resulted in to discovery of _______.
Question 16 :
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 17 :
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 18 :
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 19 :
An atom with 3 protons and 4 neutrons will have a valency of
Question 21 :
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 22 :
Helium atom has a valency of zero, even after having 2 electrons in its valence shell, because
Question 23 :
State true or false: Helium atom has 2 electrons in its valence shell but its valency is not 2.
Question 24 :
Which of the following scientist identified the 'Atomic number' in the structure of an atom ?
Question 25 :
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 26 :
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 27 :
Calculate the number of neutrons present in the nucleus of an element X which is represented as $_{15}^{31}X$.
Question 28 :
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 29 : <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 30 :
Which of the following scientist identified the 'Stationary orbits' in the structure of an atom ?
Question 31 :
Which of the following element has an atom with one electron, one proton and no neutron ?
Question 32 :
Rutherford’s 'alpha ($\alpha$) particles scattering experiment’ resulted in to discovery of _______.
Question 33 :
Which of the following scientist identified the 'Neutron' in the structure of an atom ?
Question 34 :
Why did Rutherford select a gold foil in his $\alpha$–ray scattering experiment?
Question 35 :
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 36 :
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 37 :
Which of the following is the correct electron distribution of chlorine atom ? (Atomic number of chlorine is 17).
Question 38 :
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 39 :
Is it possible for the atom of an element to have one electron, one proton and no neutron. (Yes/No)
Question 40 :
Helium atom has a valency of zero, even after having 2 electrons in its valence shell, because
