Question

For the following statements, write T for true and F for false.
(a) J.J. Thomson proposed that the nucleus of an atom contains only nucleus.
(b) A neutron is formed by an electron and a proton combining together therefore, it is neutral.
(c) The mass of an electron is about $\dfrac{1}{2000}$ times that of the proton.
(d) An isotope of iodine is used for making tincture iodine, which is used as a medicine.

Answer 1

Hint: Thomson model of an atom describes that positive charge and the electrons are uniformly distributed so that the atom as a whole is electrically neutral. Electrons are negatively charged particles, protons are positively charged particles and neutrons are neutral particles and among all these particles, the mass of the electron is the greatest of all. Iodine solution along with potassium /sodium iodide is used as an antiseptic on wounds. Now identify the statements whether they are true or false.

Complete step by step solution:
To know which of the above given statements are true or false, let’s discuss the statements one by one.
(a) J.J. Thomson proposed that an atom possesses a spherical shape in which the positive charge is uniformly distributed and the electrons are arranged in a proper manner so as to maintain the electrical neutrality of the atom. So, the first statement is false.
(b) neutrons are electrically neutral particles and are not formed by the combining of the electron and the proton. In fact, these particles were discovered by Chadwick by bombarding a thin sheet of beryllium by alpha particles. So, this statement is also false.
(c) Electrons are negatively charged particles and protons are positively charged particles and the mass of electron (i.e. $9.1\times {{10}^{-31}}$) is always more than the mass of proton(i.e.$1.67\times {{10}^{-27}}$) i.e. $\dfrac{1}{2000}$times the mass of proton. So, this statement is true.
(d) Two to seven percent solution of iodine in sodium or potassium iodide is called a tincture of iodine. Tincture of iodine is a form of iodine solution which has antiseptic properties i.e. it protects the wounds against the infections of the micro-organisms and thus, used as a medicine. So, this statement is also true.

Hence, from the above given all statements, statements (a) and (b) are false and statements (c) and (d) are true.

Note: The Thomson model of an atom is known by many names such as plum pudding, raisin pudding or watermelon. It is so because this model can be visualized as a pudding or watermelon of positive charge with plums or seeds(electrons) embedded in it.