What are nucleons ? Answer: Atomic number [Z] : “Is the number of protons in the nucleus of an atom.” OR “Is the number of positive charges in the nucleus of its atom.” (CBSE 2012, 2014, 2016) Answer: No. Questions Based on Class 9 NCERT Science Chapter Q.1: Define atomic number. (1984) Define the terms : atomic number, mass number and electron. ; Symbol: Z See more. Question 1. It is denoted by ‘Z’. Abbreviation: at. Protons and neutrons present in the nucleus of an […] Forge: for hydrogen Z= 1, because in hydrogen atom the number of protons is 1. How it is denoted ? It depicts how many times an atom of an element is heavier than one-twelth (1/12 th) the mass of one atom of carbon-12 of mass of one carbon atom.The relative atomic masses of all elements have been established with reverence to … Is this element a metal or a non – metal. Give any two uses of isotopes. Atomic Number: The number of the protons present in the nucleus of an atom is called atomic number. Atomic mass refers to the mass of an atom. Solution: Since atomic number of carbon = 6 Therefore, number of proton = 6 Now, Atomic mass = number of proton + number of neutron Or, Atomic mass or mass number = 6 + 6 = 12 u Thus, mass number or atomic mass of carbon = 12u (3) The atomic number of oxygen is 8 and number of neutron is equal to 8. Atomic mass. Class IX Science NCERT Solution for Structure of the Atom. Define atomic number. Atomic number (z) is the number of protons in an atom; it is also equal to the number of electrons in the atom. Mass Number: The number of the neutrons and protons present in the nucleus is called mass number. Question.2. QUESTIONS FROM NCERT TEXTBOOK. Atomic number = Number of protons Example: The atomic (i) Atomic number, (ii) Mass number, (iii) Isotopes and (iv) Isobars. Atomic number Atomic number (z) is the number of protons in an atom; it is also equal to the number of electrons in the atom. Previous Year Questions of Atomic Structure and Chemical Bonding for ICSE Class-9 Chemistry . Q.2: What is an electron? of electrons = Atomic number =16 Find the number of protons, electrons and neutrons in it. Answer. Number of protons of an atom determines its atomic number. Ans. State its valency. Q.4: Study the composition of the two nuclei of two atomic species L and M L = protons 20, neutrons 20 M = protons 18, neutrons 22 Give the relation between the two. no. Important Questions for CBSE Class 9 Science Chapter 2 Is Matter Around us Pure IMPORTANT QUESTIONS 1 MARK QUESTIONS Question.1. Who discovered it? of protons = Atomic number =16 No. Answer. It is represented as Z. Justify your, answer. i) Atomic number = It is the number of protons present inside nucleus of the atom. Define valency by taking examples of silicon and oxygen. Find the atomic mass or mass number of carbon. Tags: Class 9 , Chemistry , Structure of The Atom Asked by Anjali Sharma 2 Answers. 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