AP 9th Class Physical Science Chapter 6 Solution – What is Inside the Atom
Andhra Pradesh SCERT 9th Class Physical Science Chapter 6 What is Inside the Atom Solution for AP 9th Class Physics/Chemistry Exam. Lots of Students of Andhra Pradesh Board will search on internet for Andhra Pradesh Class 9 Physical Science Textbook Solution or Study Material for AP 9th exam. Here you search will end! Here in this page we have provided for all question answer for AP SCERT Chapter 6 What is Inside the Atom.
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AP 9th Class Chemistry Chapter 6 What is Inside the Atom Solution
(1) What are the three subatomic particles? (AS1)
Ans: – The subatomic particles are protons, neutrons and electron.
(2) Compare the characteristics of electrons, protons and neutrons.(AS1)
Ans:-
Protons | Electrons | Neutrons |
Its charge is +1.6×10^-19. | Its charge is -1.6×10^-19. | Charge is zero. |
Its mass is
1.67×10^-27 kg. |
Its mass is
9.1×10^-31kg. |
Its mass is
1.67×10^-27kg. |
It present inside the nucleus. | It present outside in nucleus. | It present inside of the nucleus. |
(3) What are the limitations of J.J. Thomson’s model of the atom?(AS1)
Ans: – There is no clear explanation how the positive and negative remain so close. It failed to explain about the stability of any atoms. It also doesn’t gave the clear idea of alpha scattering of Rutherford model.
(4) What were the three major observations Rutherford made in the gold foil experiment?(AS1)
Ans: –The three major observation of Rutherford model is –
- Most of the alpha particles passes through the gold foil in this model.
- Some of the particles deflected by foil.
- 1 out of 1200 alpha particle rebound back surprisingly.
(5) Sketch Rutherford’s atomic model. Why Rutherford’s model of the atom is called the planetary model?(AS5)
Ans: – In Rutherford model there are positive and negative ion are present. The positive ion mostly present in centre and negatively charge are moving outside it. So these configuration are similar to planetary model.
(6) Put tick (√) against correct choice and cross (×) against wrong choice: (AS1)
i) In Rutherford’s gold foil experiment, majority of alpha particles passed directlythrough the gold foil. This observation leads to which conclusion?
a) The positive region of the atom is very small. (√)
b) The majority of the atom must consist of empty space. (√)
c) The alpha particle makes a direct hit on the positive region. (×)
d) The positive region of the atom is very dense. (×)
ii) In Rutherford’s gold foil experiment, occasionally the alpha particle veered froma straight-line path. This observation leads to which conclusion?
a) The positive region of the atom is very small. (√)
b) The majority of the atom must consist of empty space. (×)
c) The alpha particle makes a direct hit on the positive region. (√)
d) The positive region of the atom is very dense. (√)
7.) Which one of the following is a correct electronic configuration of sodium? (AS1)
Ans: –d) 2, 8, 1.
8.) Give the main postulates of Bohr’s model of an atom. (AS1)
Ans: – The main postulates of Bohr’s model of an atom are –
- The electron revolves in the circular path outside the nucleus.
- There is no radiation of energy for revolving of electron.
- The orbit denotes as K, L, M…and this are no like 1,2,3….
- When an electron jumps to other orbit energy gainand vice versa.
9.) Compare all the proposed models of an atom given in this chapter.(AS1)
Ans:-
Rutherford model | Thomson model | Bohr’s Model |
Large empty space between electron and nucleus. | The atoms are equal in magnitude in Thomson model. | In this model electron doesn’t radiate energy in revolving. |
The thought of this model was created by Ernst Rutherford. | It was created by JJ Thomson. | It was proposed by Neil’s Bohr. |
10.) Define valency by taking examples of nitrogen and boron.(AS1)
Ans: – Valency is known by how many electron needed or looses to fill up octate of any element.
As in nitrogen (2, 5) it needed 3 electron to fill up octet so its valency is 3.
Similarly boron (2, 3) want to lose its 3 electron present in the last shell so its valency is 3.
11.) State the valences of the following elements: Magnesium and Sodium (AS1)
Ans: – The electronic configuration of Mg is 2, 8, and 2 so it want to loose last two electron to become octate so its valency is 2.
The electronic configuration of Na (11) is 2, 8, and 1 so it also want loose last electron to become octet fill up, so its valency is 1.
12.) If Z = 5, what would be the valency of the element? (AS2)
Ans: – Z = 5 so its configuration is 2, 3. so its valency will be 3.
13.) Write the atomic number and the symbol of an element which has mass number 32and the number of neutrons 16 in the nucleus. (AS1)
Ans: –As we all that,Mass number = protons + neutrons.
Here mass no is 32 and neutron is 16 so its no of protons is 32 -16 =16, which is sulphur and its symbol is S.
14.) Cl- has completely filled K&L shells. Explain. (AS1)
Ans: –In Cl (17) the electronic configuration is 2, 8, and 7. But in Cl- (18) the electronic configuration is 2, 8, and 8. So by seeing its electronic configuration we can say that completely filled k and L shell present in Cl- atom.
15.) What is the main difference between isotopes of the same element? (AS1)
Ans: –The main difference between the isotopes of the same element is the neutrons no.
16.) For the following statements, write T for True and F for False. (AS1)
J.J. Thomson proposed that the nucleus of an atom contains only nucleons. (F)
A neutron is formed by an electron and a proton combining together. Therefore, it is neutral. (F)
The mass of an electron is 1/2000 times that of proton. (T)
17.) Fill in the missing information in the following table. (AS4)
Ans:-
Name | Symbol | Atomic number | Mass number | No of neutrons | No of electrons |
Oxygen | 16O8 | 8 | 16 | 8 | 8 |
Nitrogen | 14N2 7 | 7 | 14 | 7 | 7 |
Beryllium | 9Be4 | 4 | 9 | 5 | 4 |
Magnesium | 24Mg12 | 12 | 24 | 12 | 12 |
Magnesium | 25Mg12 | 12 | 25 | 13 | 12 |
Sulphur | 34S16 | 16 | 34 | 18 | 16 |
18.) How do you appreciate the efforts made by scientists to explain the structure ofatom by developing various atomic models? (AS6)
Ans: –The presence of atom was predicted by philosopher many time ago but that was first proved by Dalton atomic model, which gives the primary idea about atomic structure. The came Thomson model and after that came Rutherford model by clearing some doubt of Thomson model. Then came Bohr’s model which clear the defect of Rutherford model. By these new developments helps us to understand the clear view about atomic structure.
19.) Geeta got a doubt, “Why atomic nucleus contains proton and neutrons inside it? Why can’t electrons and neutrons?” Can you help to clarify her doubt? Explain. (AS1)
Ans: – Proton mass is 2000 times more than the electron so this heavy mass remain in centre in atomic structure model or in nucleus.
As there is repulsion force between the same protons present in the nucleus for this neutrons exists in nucleus and electron are revolving around nucleus.
20.) Collect information about various experiments conducted and theories proposed by scientists starting from John Dalton to Niels Bohr and prepare a story with a title “History of atom”.(AS4)
Ans: –The theory of different scientist about the atomic structure of atom are –
- At first Dalton gives the idea about the atom he says it can’t be split and we can’t see this atom with our naked eyes.
- Then came Thomson idea which tell us that negatively charge particle are present outside of positively charge particle cloud.
- In his alpha scattering experiment Rutherford show’s us that there present a nucleus in an atom and electron are moving around it.
- After that Neil’s Bohr theory clear the doubts was seen in Rutherford model and stated that there present different energy level in an atomic structure and electron have to gain or loose energy when it jumps to other orbital or energy level.