Page 126 - Chemistry ICSE Class IX
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114 ICSE Chemistry – 9
34. 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 nucleon.
(b) A neutron is formed by an electron and proton combining together, therefore, it is neutral.
(c) The mass of an electron is about 1840 times that of proton.
(d) Matter is electrical in nature and negatively charged.
(e) An isotope of iodine is used for making tincture iodine, which is used as a medicine.
35. Tick (9) the correct answer.
(i) Cathode rays are produced when high electrical potential is applied to a gas held in a discharge tube at a
pressure of about
–3
(a) 10 atm
–5
(b) 10 atm
(c) 1 atm
(d) 100 atm
(ii) An atom consists of an equal number of
(a) neutrons and protons
(b) protons and electrons
(c) neutrons and electrons
(d) protons and positrons
(iii) The nucleus of hydrogen atom is called
(a) neutron
(b) positron
(c) proton
(d) positive rays
(iv) Atoms of an element which contain equal number of protons, but different number of neutrons are called
(a) isobars
(b) isotones
(c) isotopes
(d) isoelectronic
(v) The maximum number of electrons which can be accommodated in the nth energy level is given by
2
(a) n
2
(b) 2n
(c) 2n
(d) n
(vi) An atom with atomic number 18 and mass number 40, has the following arrangement:
(a) 18p, 18e, 22n
(b) 18p, 18e, 40n
(c) 22p, 18e, 18n
(d) 22p, 22e, 18n
(vii) An alpha-particle is
(a) an ionised hydrogen atom
(b) an ionised helium atom 
