The positively charged part at the center of an atom is called as :
Correct Answer:
(D)
Nucleus
The positively charged part at the centre of an atom is called as nucleus. The atomic nucleus is the small, dense region consisting of proton and neutron at the centre of an atom.
Ques:
22
Which of the following is not a part of an atom?
Correct Answer:
(D)
Photon
Proton, electron and neutron are part of an atom, but the photon is associated with light energy and also known as energy packet of light.
Ques:
23
A single type of atom is found in –
Correct Answer:
(C)
Native elements
Native element is a material that consists of a single type of atom, while a compound consists of two or more types of atoms.
Ques:
24
The atomic nucleus was discovered by :
Correct Answer:
(A)
Rutherford
The nucleus is a very dense region consisting of protons and neutrons at the centre of an atom. It was discovered in 1911 as a result of Ernest Rutherford’s interpretation of the 1909 Geiger–Marsden gold foil experiment. The proton–neutron model of the nucleus was proposed by Dmitri Ivanenko in 1932.
Ques:
25
In atom, neutron was discovered by :
Correct Answer:
(B)
Chadwick
Neutron is a neutral particle which has no electrical charge. It was discovered by Chadwick in 1932. He discovered that when Beryllium (Be) or other atoms are bombarded with high speed particles, then electrically neutral particles emerges from these atoms and such neutral particles are known as neutrons.
Ques:
26
Which one of the following pairs constitutes particle- antiparticle pair?
Correct Answer:
(A)
Electron - Positron
The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. The positron has a positive electric charge and has the same mass as an electron.
Ques:
27
Match List-I with List-II and select the correct answer using the codes given below the lists :
List-I (Characteristic) List-II (Particle)
A. Zero mass 1. Positron
B. Fractional charge 2. Neutrino
C. Fractional spin 3. Quark
D. Integral spin 4. Phonon
Code :
A B C D
Correct Answer:
(A)
2 3 1 4
The positron has a positive electric charge (+1e) and has the same mass and a spin of 1/2 as an electron. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons and are the components of atomic nuclei. They have fractional charge of +2/3e or -1/3e. Neutrinos are sub-atomic particles produced by the decay of radioactive elements and are elementary particles that lack an electric charge and a very small mass, which might even be zero. Phonon, in condensed-matter physics, a unit of vibrational energy that arises from oscillating atoms within a crystal. A phonon is a definite discrete unit or quantum of vibrational mechanical energy, just as a photon is a quantum of electromagnetic or light energy. Phonon has integral spin like photon.
Ques:
28
Which one is a fundamental particle?
Correct Answer:
(D)
Quark
In particle physics, an elementary particle or fundamental particle is a subatomic particle with no sub-structure, thus not composed of other particles. Particles currently thought to be elementary include the fundamental fermions (quarks, leptons, antiquarks and antileptons) as well as fundamental bosons.
Ques:
29
Higgs Boson are also known as :
Correct Answer:
(D)
God Particles
The Higgs Boson is the fundamental particle associated with the Higgs field, a field that gives mass to other fundamental particles such as electrons and quarks. In the mainstream media, the Higgs boson has often been called the 'God Particle' from the 1993 book 'The God Particle' by Nobel Laureate Leon Lederman.
Ques:
30
A pure substance which contains only one type of atom is called:
Correct Answer:
(A)
Element
A pure substance which contains only one type of atoms is an element.An element contains only one type of atoms. It cannot be broken down or transformed into a simpler substance. Elements combine chemically in fixed proportions to form another type of a pure substance called a compound. Examples of elements are oxygen (O), fluorine (F) etc. Examples of compounds are water (H2O), sodium chloride (NaCl) etc.