a) Which of the following models does not correspond to the Thomson Model of Atom?
- plum pudding model
- watermelon model
- raisin pudding model
- nuclear model
b) Rutherford in his atomic model could not explain which of the following behaviour?
c) What is the absolute charge of a proton?
d) Who discovered electrons?
- J. J. Thomson.
- Neils Bohr.
- James Chadwick.
e) Which of the following is responsible for the mass of an atom?
- Only protons.
- Only neutrons.
- Neutrons and protons.
- Protons and electrons.
f) Which of the following determines the atomic number of an atom?
- Number of electrons.
- Number of protons.
- Number of electrons and protons.
- Number of protons and neutrons.
g) Who proposed the atomic theory?
- John Dalton.
- Robert Millikan.
- J. J. Thomson.
- Neil’s Bohr.
h) The maximum mass of an atom is concentrated in which of these?
i) Rutherford carried out experiments in which a beam of alpha particles was directed at a thin piece of metal foil. From these experiments, he concluded that:
- the positively charged parts of atoms are moving about with a velocity approaching the speed of light.
- the positively charged parts of atoms are extremely small and extremely heavy particles.
- the diameter of an electron is approximately equal to that of the nucleus
- electrons travel in circular orbits around the nucleus.
j) Which of the following has a positive charge?
k) Which of the following is not an isotope of hydrogen?
l) Chemical properties of an atom are dependent on a number of electrons in that particular atom.
m) The nucleons are
- Protons and electrons
- Neutrons and electrons
- Protons and neutrons
- None of these
n) Which of the following statements you think is wrong regarding α particle scattering effect?
- α particles mostly move through the gold foil having zero deflection
- Deflection of small fraction
- One in Twenty Thousand turns 180°
- The thickness of the gold foil is about 100μm
a – 4 [ Thomson proposed a model of the atom, in which electrons are embedded to make it as the stable electrostatic arrangement and such that positive charge is equally distributed around a sphere. Mass is assumed to be equally distributed. So, it has different names like plum pudding, watermelon and raisin pudding model.]
b – 1 [ Rutherford failed to explain the arrangement of electrons in an atom. Like Maxwell, he was unable to explain the stability of the atom.]
c – 2 [ According to the fundamental properties of particles, protons charge is +1.602176×10-19C. It is a subatomic particle. Rutherford discovered protons. Its elementary charge is 1. Proton’s charge is positive.]
d – 2 [ During the 1880s and ’90s scientists searched cathode rays for the carrier of the electrical properties in matter. Their work culminated in the discovery by English physicist J.J. Thomson of the electron in 1897. Ernest Rutherford published his results proving the existence of the proton. James Chadwick announced that the core also contained a new uncharged particle, which he called the neutron. Niels Bohr proposed a theory for the hydrogen atom.
e – 3 [ Protons and neutrons are the fundamental particles whose masses are mainly responsible for the mass of an atom].
f – 2 [ The number of protons in a nucleus is the atomic number and is always equal to the number of electrons in orbit about that nucleus].
g – 4 [ Dalton proposed his atomic theory in 1808; another century passed before the theory was universally accepted by scientists].
h – 1 [ The mass of the atom is concentrated in the nucleus (protons and neutrons are about 2000 times as heavy as electrons].
i – 2 [ Rutherford fired alpha particles at a thin gold foil. After carrying out the experiment, he concluded that the atoms were mainly empty space, and that most of the matter was contained in a small, very dense, positively charged object that was more massive than the alpha particle].
j – 1 [ protons are positively charged, neutrons are uncharged and electrons are negatively charged].
k – 4 [ Protium has only 1 proton, deuterium has one proton and 1 neutron whereas tritium has one proton and two neutrons. They are also represent by 1H1, 1D2 and 1T3. Helium has 2 protons and two neutrons, hence can’t consider as an isotope. Isotope means having the same number of protons but differ in the number of neutrons].
l – 1 [ Yes, the chemical properties of an atom are dependent on the number of electrons in that particular atom, which in turn is decided by the number of protons present in that atom. The number of neutrons has only a small effect on this.]
m – 3 [ A nucleon is the collective name for two important subatomic particles: neutrons and protons. For instance, protons and neutrons are nucleons, since they are in the nucleus of the atom. Nucleons are made of quarks].
n – 4 [In this effect, a thin foil (thickness 100nm) made up of gold and coated with fluorescent ZnS screen which is circular around it. α particles mostly move through the gold foil having zero deflection, a small fraction is deflected and one in twenty thousand turns 180°].