NCERT EXAMPLER CLASS 9 SCIENCE CHAPTER 4-STRUCTURE OF THE ATOM

 Multiple Choice Questions

1. Which of the following correctly represent the electronic distribution in the Mg atom?

(a) 3, 8, 1

(b) 2, 8, 2

(c) 1, 8, 3

(d) 8, 2, 2

2. Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in to

discovery of

(a) Electron

(b) Proton

(c) Nucleus in the atom

(d) Atomic mass

3. The number of electrons in an element X is 15 and the number of neutronsis 16. Which of the following is the correct representation of the element?

(a) 31

           X

     15

(b) 31

            X

     16 

(c) 16  

          X

     15

(d)  15

           X

       16

4. Dalton’s atomic theory successfully explained

(i) Law of conservation of mass

(ii) Law of constant composition

(iii) Law of radioactivity

(iv) Law of multiple proportion

(a) (i), (ii) and (iii)

(b) (i), (iii) and (iv)

(c) (ii), (iii) and (iv)

(d) (i), (ii) and (iv)

5. Which of the following statements about Rutherford’s model of atom are

correct?

(i) considered the nucleus as positively charged

(ii) established that the α–particles are four times as heavy as a hydrogen

atom

(iii) can be compared to solar system

(iv) was in agreement with Thomson’s model

(a) (i) and (iii)

(b) (ii) and (iii)

(c) (i) and (iv)

(d) only (i)

6. Which of the following are true for an element?

(i) Atomic number = number of protons + number of electrons

(ii) Mass number = number of protons + number of neutrons

(iii) Atomic mass = number of protons = number of neutrons

(iv) Atomic number = number of protons = number of electrons

(a) (i) and (ii)

(b) (i) and (iii)

(c) (ii) and (iii)

(d) (ii) and (iv)

7. In the Thomson’s model of atom, which of the following statments are correct?

(i) the mass of the atom is assumed to be uniformaly distributed over the atom

(ii) the positive charge is assumed to be uniformaly distributed over the atom

(iii) the electrons are uniformaly distributed in the positively charged sphere

(iv) the electrons attract each other to stabilise the atom

(a) (i), (ii) and (iii)

(b) (i) and (iii)

(c) (i) and (iv)

(d) (i), (iii) and (iv)

8. Rutherford’s α–particle scattering experiment showed that

(i) electrons have negative charge

(ii) the mass and positive charge of the atom is concentrated in the nucleus

(iii) neutron exists in the nucleus

(iv) most of the space in atom is empty

Which of the above statements are correct?

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (i) and (iv)

(d) (iii) and (iv)

9. The ion of an element has 3 positive charges. Mass number of the atom is27 and the number of neutrons is 14. What is the number of electrons in the ion?

(a) 13

(b) 10

(c) 14

(d) 16

11. In a sample of ethyl ethanoate (CH3COOC2H5) the two oxygen atoms have the same number of electrons but different number of neutrons. Which oft the following is the correct reason for it?

(a) One of the oxygen atoms has gained electrons

(b) One of the oxygen atoms has gained two neutrons

(c) The two oxygen atoms are isotopes

(d) The two oxygen atoms are isobars.

12. Elements with valency 1 are

(a) always metals

(b) always metalloids

(c) either metals or non-metals

(d) always non-metals

13. The first model of an atom was given by

(a) N. Bohr

(b) E. Goldstein

(c) Rutherford

(d) J.J. Thomson

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

(a) 3

(b) 7

(c) 1

(d) 4

15. The electron distribution in an aluminium atom is

(a) 2, 8, 3

(b) 2, 8, 2

(c) 8, 2, 3

(d) 2, 3, 8

17. Which of the following statement is always correct?

(a) An atom has equal number of electrons and protons.

(b) An atom has equal number of electrons and neutrons.

(c) An atom has equal number of protons and neutrons.

(d) An atom has equal number of electrons, protons and neutrons.

18. Atomic models have been improved over the years. Arrange the following atomic models in the order of their chronological order 

(i) Rutherford’s atomic model

(ii) Thomson’s atomic model

(iii) Bohr’s atomic model

(a) (i), (ii) and (iii)

(b) (ii), (iii) and (i)

(c) (ii), (i) and (iii)

(d) (iii), (ii) and (i)

NCERT EXAMPLER CLASS 9 SCIENCE CHAPTER 3-ATOMS AND MOLECULES

Multiple Choice Questions

 1. Which of the following correctly represents 360 g of water?

(i) 2 moles of H20

(ii) 20 moles of water

(iii) 6.022 × 10^23 molecules of water

(iv) 1.2044×10^25 molecules of water

(a) (i) 

(b) (i) and (iv)

(c) (ii) and (iii)

 (d) (ii) and (iv)

2. Which of the following statements is not true about an atom?

(a) Atoms are not able to exist independently

(b) Atoms are the basic units from which molecules and ions are formed

(c) Atoms are always neutral in nature

(d) Atoms aggregate in large numbers to form the matter that we can see,

feel or touch

3. The chemical symbol for nitrogen gas is

(a) Ni 

(b) N2 

(c) N+

 (d) N

4. The chemical symbol for sodium is

(a) So

 (b) Sd

 (c) NA

 (d) Na

5. Which of the following would weigh the highest?

(a) 0.2 mole of sucrose (C12 H22 O11)

(b) 2 moles of CO2

(c) 2 moles of CaCO3

(d) 10 moles of H2O

6. Which of the following has maximum number of atoms?

(a) 18g of H2O

(b) 18g of O2

(c) 18g of CO2

(d) 18g of CH4

7. Which of the following contains maximum number of molecules?

(a) 1g CO2

(b) 1g N2

(c) 1g H2

(d) 1g CH4

8. 3.42 g of sucrose are dissolved in 18g of water in a beaker. The number of oxygen atoms in the solution are

(a) 6.68 × 10^23

(b) 6.09 × 10^22

(c) 6.022 × 10^23

(d) 6.022 × 10^21

9. Which of the following correctly represents 360 g of water? A change in the physical state can be brought about

(a) only when energy is given to the system

(b) only when energy is taken out from the system

(c) when energy is either given to, or taken out from the system

(d) without any energy change

NCERT EXAMPLER CLASS 9 SCIENCE CHAPTER 2-IS MATTER AROUND US

 Multiple Choice Questions

1. Which of the following statements are true for pure substances?

(i) Pure substances contain only one kind of particles

(ii) Pure substances may be compounds or mixtures

(iii) Pure substances have the same composition throughout

(iv) Pure substances can be exemplified by all elements other than nickel

(a) (i) and (ii)

(b) (i) and (iii)

(c) (iii) and (iv) 

(d) (ii) and (iii)

2. Rusting of an article made up of iron is called

(a) corrosion and it is a physical as well as chemical change

(b) dissolution and it is a physical change

(c) corrosion and it is a chemical change

(d) dissolution and it is a chemical change

3. A mixture of sulphur and carbon disulphide is

(a) heterogeneous and shows Tyndall effect

(b) homogeneous and shows Tyndall effect

(c) heterogeneous and does not show Tyndall effect

(d) homogeneous and does not show Tyndall effect

4. Tincture of iodine has antiseptic properties. This solution is made by dissolving

(a) iodine in potassium iodide

(b) iodine in vaseline

(c) iodine in water

(d) iodine in alcohol

5. Which of the following are homogeneous in nature?

(i) ice (ii) wood (iii) soil (iv) air

(a) (i) and (iii)

(b) (ii) and (iv)

(c) (i) and (iv)

(d) (iii) and (iv)

6. Which of the following are physical changes?

(i) Melting of iron metal

(ii) Rusting of iron

(iii) Bending of an iron rod

(iv) Drawing a wire of iron metal

(a) (i), (ii) and (iii)

(b) (i), (ii) and (iv)

(c) (i), (iii) and (iv)

(d) (ii), (iii) and (iv)

7. Which of the following are chemical changes?

(i) Decaying of wood

(ii) Burning of wood

(iii) Sawing of wood

(iv) Hammering of a nail into a piece of wood

(a) (i) and (ii)

(b) (ii) and (iii)

(c) (iii) and (iv)

(d) (i) and (iv)

8. Two substances, A and B were made to react to form a third substance,

A2B according to the following reaction

2 A + B → A2 B

Which of the following statements concerning this reaction are incorrect?

(i) The product A2B shows the properties of substances A and B

(ii) The product will always have a fixed composition

(iii) The product so formed cannot be classified as a compound

(iv) The product so formed is an element

(a) (i), (ii) and (iii),

(b) (ii), (iii) and (iv)

(c) (i), (iii) and (iv)

(d) (ii), (iii) and (iv)

9. Two chemical species X and Y combine together to form a product P which contains both X and Y

X + Y → P

X and Y cannot be broken down into simpler substances by simple chemicalreactions. Which of the following concerning the species X, Y and P are correct?

(i) P is a compound

(ii) X and Y are compounds

(iii) X and Y are elements

(iv) P has a fixed composition

(a) (i), (ii) and (iii)

(b) (i), (ii) and (iv)

(c) (ii), (iii) and (iv)

(d) (i), (iii) and (iv)

NCERT EXAMPLER CLASS 9 SCIENCE CHAPTER 1- MATTER IN OUR SURROUNDINGS

Multiple Choice Questions

1.Which one of the following sets of phenomena would increase on raising the temperature?

A)Diffusion, evaporation, compression of gases
B) Evaporation, compression of gases, solubility
C) Evaporation, diffusion, expansion of gases
D) Evaporation, solubility, diffusion, compression of gases

... Answer is C)
Evaporation, diffusion, expansion of gases

2.Seema visited a Natural Gas Compressing Unit and found that the gas can be liquefied under specific conditions of temperature and pressure. While sharing her experience with friends she got confused. Help her to identify the correct set of conditions

A) Low temperature, low pressure
B) High temperature, low pressure
C) Low temperature, high pressure
D) High temperature, high pressure

... Answer is C)
Low temperature, high pressure

3.The property to flow is unique to fluids. Which one of the following statements is correct?

A)Only gases behave like fluids
B) Gases and solids behave like fluids
C) Gases and liquids behave like fluids
(d) Only liquids are fluids

... Answer is C)
Gases and liquids behave like fluids

4. During summer, water kept in an earthen pot becomes cool because of the phenomenon of

(a) diffusion
(b) transpiration
(c) osmosis
(d) evaporation

... Answer is D)
evaporation

5. A few substances are arranged in the increasing order of ‘forces of attraction’ between their particles. Which one of the following represents a correct arrangement?

A) Water, air, wind
B) Air, sugar, oil
C) Oxygen, water, sugar
D) Salt, juice, air

... Answer is C)
Oxygen, water, sugar

6. On converting 25°C, 38°C and 66°C to kelvin scale, the correct sequence of temperature will be

A)298 K, 311 K and 339 K
B)298 K, 300 K and 338 K
C)273 K, 278 K and 543 K
D)298 K, 310 K and 338 K

... Answer is A)
298 K, 311 K and 339 K

7.Choose the correct statement of the following

A) conversion of solid into vapours without passing through the liquid state is called sublimation.
B) conversion of vapours into solid without passing through the liquid state is called vapourisation..
C) conversion of vapours into solid without passing through the liquid state is called freezing.
D) conversion of solid into liquid is called sublimation.

... Answer is A)
conversion of solid into vapours without passing through the liquid state is called sublimation.

8.The boiling points of diethyl ether, acetone and n-butyl alcohol are 35°C,56°C and 118°C respectively. Which one of the following correctly represents their boiling points in kelvin scale?

A) 306 K, 329 K, 391 K
B)308 K, 329 K, 392 K
C) 308 K, 329 K, 391 K
D) 329 K, 392 K, 308 K

... Answer is C)
308 K, 329 K, 391 K

9.Which condition out of the following will increase the evaporation of water?

A) Increase in temperature of water
B)Decrease in temperature of water
C)Less exposed surface area of water
D) Adding common salt to water

... Answer is A)
Increase in temperature of water

10.In which of the following conditions, the distance between the molecules of hydrogen gas would increase? (i) Increasing pressure on hydrogen contained in a closed container (ii) Some hydrogen gas leaking out of the container (iii) Increasing the volume of the container of hydrogen gas (iv) Adding more hydrogen gas to the container without increasing the volume of the container

A)(i) and (iii)
B)(i) and (iv)
C)(ii) and (iii)
D) (ii) and (iv)

... Answer is C)
(ii) and (iii)