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Thursday, 25 June 2015

structure of atom (Questions)

Structure of the Atom ,notes,chemistry 9 ,free notes,electron,protons,bohrs model,
Structure of the Atom  
Fill Ina the Blanks
1. The electronic configuration of asilicon is ___. (Atomic number = 14)

 2. _____ electrons are responsible for the chemical properties of an atom.

 3. Rutherford’s model of an atom wasa modified by _______.

4.____ is an isotope of carbon used in adetermining the age of dead plants.

5. An atom with 3 protons and 4 neutrons will have a valency of _________.

Q 1. In a sample of ethyl ethanoate (CH3 COOC2 H5) the two oxygen atoms have the same number of electrons but different anumber of neutrons. What can be the reason for it? (2 marks) 

Q 2. In the atom of element X, 6 electrons are present ain the outermost shell. If it requires an octet configuration by accepting requisite number of electrons, then what would be the charge on the ion so formed? (2 marks)

Q 3.Why do helium, neon a & argon have a zero valency? (2 mark)

Q 4. Write the atomic number and the  symbol of an element which has mass number 32 and thea number of neutrons 16 in the nucleus. (2 marks)

Q 5. Helium atom has an atomic mass of 4 u and two protons in its nucleus. How many neutrons does it have? (2 marks)

Q 6. If number of aelectrons in an aatom is 8 and number of protons is also 8,then (i) what is the atomica number of the atom? and (ii) what is the charge on the atom? (2 marks)

Q 7. What are the limitations of J. J. Thomson's model of the atom?

Q.8. If bromine atom is in the form of say two isotopes 7935Br (49.7%) and 8135Br (50.3%), then calculate the average mass of bromine atom.

Q9. The average atomic mass of a sample of an element X is 16.2u. What are the percentage of isotopes 168X and18 8X in the sample?

Q 10. Define valency by taking examples of silicon and oxygen.

1 1. The atomic radius of hydrogen atom is

 (a). 0.037 nm (b.) 0.037 x 10 -9 m (c.) both a &b (d). none

2. Complete the following sentence : In water, the proportion of hydrogen and oxygen is ---------- by mass 
(a.) 1:8 (b). 3:4 (c). 9:0 (d). none

3. The actual mass of hydrogen atom 

(a). 1.673 x 10 -24 g( b). 1.673 x 10 (c).1u (d.) both a & b 

4. The symbol of cobalt a.C.o. b. CO c. Co. d. none

5. Atomicity of noble gases is one 

a. True b. false c. can‟t say d none

6. The molecular mass of sulfuric acid 

a. 28 u b. 108 u c. 98u d. none

7. What are the number of  electron and proton in chlorine ion 

a. 17p & 18 e b. 18 p & 17 e c. 17 e & 0 e d. none

8. The value of symbol „L‟ a. 6.022 x 10 23 b. 6.022 x 10 -23 c. 0.622 x 10 23 d. none

9. What is the mass of of 0.2 moles of oxygen atoms? a. 2.3 g b. 3.2 g c. .32 g d. none

10. Write the atomicity of CO2 gas a. 2 b. 3 c. 0 d. none

(Section B) 10 X 1 = 10

1.what is meant by saying “the atomic mass of oxygen is 16”?

2. What is the significance of formula H2O?

3. Calculate the formula mass of calcium chloride and sodium carbonate

4. An element Z forms an oxide ZO3. What is the valency of Z?

5. Write the Latin names of sodium, iron, mercury and tin.

6. Define 1 u.

7. Define electro negativity of any atom.

8. Name the element represent by the following symbols Hg, Pb, Au, Ag and Sn

9. Write down the atomicity of carbon dioxide, oxygen, ozone, solid sulphur.

10. Write down the atomicity of carbon dioxide, oxygen, ozone, solid sulphur.

(Section C) 5 x 2 = 10

1. Write down the atomicity of carbon dioxide, oxygen, ozone, solid sulphur.

2. Give major draw –backs of Dalton‟s atomic theory of matter.

3. Work out the formula of magnesium chloride.

4. The mass of a single atom of an element X is 2.65 x 10 -23g. What is its atomic mass? 

What could this element.

5. Calculate the molar mass of the following  Ethyne and nitric acid

(Section D) 2 x 2.5 = 5

6. State the law of conservation of mass. Give one example also.

7. In an experiment, 1.288 g of copper oxide was obtained from 1.03 g of copper. In another experiment 3.672 g of copper oxide obtain from the 2.938 g of copper. Show that these figures verify the law of constant proportion.

1 marks questions

1. Define cathode rays.

2. What determines the chemical nature of an element?

3. Write the electronic configuration of chlorine.

4. What do you mean by atomic number of an element?

5. What do you understand by isobars?

2 marks questions

1. How the mass number of an element is defined

2. What is the mass and charge of an electron?

3. What are isotopes? Give examples

4. Helium atom has a mass number of 4 and 2 protons in its nucleus. How many neutrons does

it have?

5. What is the general name  of the elements having 2 or 8 electrons in the valence shell of

their atoms?

3 marks questions

1. Draw a sketch of Bohr’s model of an atom with four shells.

2. Name the radio isotopes used to–(a) determine the activity of thyroid gland. (b) detect blood


3. What weight in grams is represented by(a) 2 moles of CO2(b) 5 moles of NH3

4. Give a brief account of the observations made by Rutherford in his alpha particle scattering

5. Define Relative Molecular Mass

Topic related to polytechnic entrance exam

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