Title Advanced series 9th class Chemistry - Solutions.pdf ✅

Class 9 – Chemistry | A -9 Atomic Structure 1 1. Atomic Structure Solutions Fundamental Particles LEVEL-I 1. Correct option: (B) John Dalton In 1808, John Dalton’s atomic theory came into existence which proposed that all matter, whether an element, a compound or a mixture is composed of small particles called atoms. 2. Correct option: (A) Democritus Around 500 BC, an Indian philosopher Maharishikanad postulated that matter is made up of indivisible small particles which he named as “Parmanu” whose idea was further elaborated by another Indian philosopher, Pakudha Katyayama. Around this era only, Democritus, a Greek philosopher called these very small particles of matter as “Atoms” which meant indivisible. 3. Correct option: (A) Atom Elements are made up of very small particles of matter called “Atoms” which was proposed by John Dalton too in his atomic theory. 4. Correct option: (D) Maharishikanada Around 500 BC, an Indian philosopher, Maharishikanada postulated that if we go on dividing matter we will get smaller and smaller particles and a stage will come when these smaller particles won’t be further divisible. He called these smaller indivisible particles as “Parmanu” 5. Correct option: (A) Elements John Dalton, in his postulates of atomic theory stated that “Atoms of different elements have different masses and chemical properties.” 6. Correct option: (B) John Dalton The first atomic theory was postulated by John Dalton in 1808 in which he proposed that all matter, whether an element, a compound or a mixture is composed of small particles called atoms. 7. Correct option: (B) -1.6022 x 10-19 C. Electrons are negatively charged particles with mass equal to 9.1 x 10-31 kg and charge equal to 1.6022 x 10-19 C. 8. Correct option: (A) Goldstein E. Goldstein in 1886 discovered the presence of new radiations in a gas discharge which were called as “Anode rays” or canal rays. 9. Correct option: (B) It is an ionized hydrogen atom • Proton is not the nucleus of a deuterium because deuterium has a one proton and one neutron in its nucleus as it has a mass number of 2.
Class 9 – Chemistry | A -9 Atomic Structure 2 • Proton is ionized hydrogen atom but not ionized hydrogen molecule because an ionized hydrogen atom consists of one proton as the electron is lost on ionization but this is not the case in ionized hydrogen molecule. • Proton is ionized hydrogen atom because on ionization electron is lost and hydrogen atom consists of 1 proton. • Proton is a positively charged particle. It is not an alpha particle. 10. Correct option: (B) 1.76 x 1011 C/kg Specific charge or e m value = Electrical charge Particle mass For an electron, charge(e) = 1.6 x 10-19 C Mass (m) = 9.1 x 10-31 kg e m ratio = 1.6 × 10−19 C 9.1 × 10−31 kg = 1. 76 × 1011 C/kg 11. Correct option: (A) Less than e/m value of electron As mass of proton is higher than that of electron, so e/m value of proton is less than that of electron. This can be also observed by the following calculation: As we know, Specific charge or e m value = Electrical charge Particle mass Charge of proton= Charge of electron= 1.6 x 10-19 C (in magnitude) Mass of electron= 9.1 x 10-31 kg Mass of proton= 1.67 x 10-27 kg Therefore, for electron, e m ratio = 1.6 × 10−19 C 9.1 × 10−31 kg = 1. 76 × 1011 C/kg And, for proton, e m ratio = 1.6 × 10−19 C 1.67 × 10−27 kg = 0. 95 × 108 C/kg From above, it is clear that e/m value of proton is less than that of electron. 12. Correct option: (A) decreases When the speed of electron increases, specific charge decreases. This is because the mass of moving electron increases with increase in velocity. Specific charge or e m value = Electrical charge Particle mass Thus, as mass increases, specific charge decreases. 13. Correct option: (B) is constant The e/m ratio of cathode rays is constant due to the following reasons: • e/m ratio is independent of type of gas present in the discharge tube.