Heena Sharma, Shubhankat Vats and, Rashmi Gupta Solutions for Chapter: Structure of the Atom, Exercise 5: Challengers*

In the Thomson's model of atom, which of the following statements are correct?

(i) The mass of the atom is assumed to be uniformly distributed over the atom.

(ii) The positive charge is assumed to be uniformly distributed over the atom.

(iii) The electrons are uniformly distributed in the positively charged sphere.

(iv) The electrons attract each other to stabilise the atom.

The atomic number of an element is $13$ and its mass, mass number is $27$. The correct order representing the number of electrons, protons and neutrons respectively in this atom is.

The following diagram depicts the Rutherford’s experiment.

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.

Which of the following are 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.

The number of electrons in an element $\mathrm{X}$is $18$ and the number of neutrons is $22$. Which of the following is the correct representation of the element? 

Different isotopes are matched with their uses as

(i) $\mathrm{Co}-60$-To treat cancer

(ii) $\mathrm{U}-238$-To produce electricity

(iii) $\mathrm{I}-131$-To treat goitre

(iv) $\mathrm{Na}-24$-In agricultural research

Which of the above matches are correct?

In a sample of ethyl ethanoate$\left({\mathrm{CH}}_3{\mathrm{COOC}}_2{\mathrm{H}}_5\right)$ 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?