4. Structure of The Atom Class 9 Science [LATEST] Solutions Additional -Questions in English - CBSE Study
NCERT Solutions for Class 9 Science are carefully prepared according to the latest CBSE syllabus and NCERT textbooks to help students understand every concept clearly. These solutions cover all important 4. Structure of The Atom with detailed explanations and step-by-step answers for better exam preparation. Each Additional -Questions is explained in simple language so that students can easily grasp the fundamentals and improve their academic performance. The study material is designed to support daily homework, revision practice, and final exam preparation for Class 9 students. With accurate answers, concept clarity, and structured content, these NCERT solutions help learners build confidence and score higher marks in their examinations. Whether you are revising a specific topic or preparing an entire chapter, this resource provides reliable and syllabus-based guidance for complete success in Science.
Class 9 English Medium Science All Chapters:
4. Structure of The Atom
3. Additional -Questions
Additional And Important Questions with solutions
Ques.1 – Why does an atom have neutral charge?
Ans. – As an atom have equal protons and electrons. The protons carry positive charge and electrons carry negative charge. Thus an atom has neutral charge.
Ques.2 – What is an alpha particle?
Ans. – Alpha particle is a double charged helium particle which has positive charge.
Ques.3 – Write the name of sub-atomic particles of an atom.
Ans. –
- Proton – it has positive charge.
- Electron – it has negative charge.
- Neutron – it has no charge.
Ques.4 – Name the founder of electron.
Ans. – J. J. Thomson
Ques.5 – What is canal rays?
Ans. – Canal rays were positively charged radiations of a gas discharged from the anode of discharged canal which ultimately led to the discovery of another sub-atomic particle.
Ques.6 – Whom does credit for discovery of proton go?
Ans – E. Goldstein.
Ques.7 – What are the limitations of J.J. Thomson’s model of the atom?
Ans. – Thomson’s model explained that atoms are electrically neutral, the results of experiments carried out by other scientists could not be explained by this model,
Ques.8 – What are the limitations of Rutherford’s model of the atom?
Ans. – According to electromagnetic principle Rutherford’s model of the atom makes unstable to an atom while an atom is stable.
Ques.9 – What postuletes Neils Bohr put about the model of an atom?
Ans. – Neils Bohr put forward the following postulates about the model of an atom:
- Only certain special orbits known as discrete orbits of electrons, are allowed inside the atom.
- While revolving in discrete orbits the electrons do not radiate energy.
Ques.10 – Describe Rutherford’s model of the atom.
Ans. – Rutherford put forward the nuclear model of an atom, which had the following features:
- There is a positively charged centre in an atom called the nucleus.
- Nearly all the mass of an atom resides in the nucleus.
- The electrons revolve around the nucleus in well-defined orbits.
- The size of the nucleus is very small as compared to the size of the atom.
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