Extra Questions
1. Is there any similarity in materials?
2. When 50 g of sugar is dissolved in 100 mL of water, there is no increase in volume. What characteristic of matter is illustrated by this observation?
3. What happens when an inflated air balloon is pricked with a pin? Name the property of the gaseous state exhibited by this observation.
4. Name the process which occurs when a drop of dettol is added to water.
5. To which physical state of matter do the following statements apply?
a. Incompressible, no fixed shape
b. Compressible, no definite volume
6. Name the state of matter in which:
a. Layers of particles can slip and slide over one another easily.
b. Particles just move around randomly because of very weak force of attraction.
7. Define density and give its SI unit.
8. In which of the following, the particles have highest forces of attraction?
Water, NaCl (solid), ice or, wax.
9. Why do the gases exert more pressure on the walls of the container than the solids?
10. Which of the following diffuses faster?
Water vapour, wax or, ethyl alcohol.
11. Why do we see water droplets on the outer surface of a glass containing ice cold water?
12. Can materials exist in all the three states?
13. Kinetic energy of particles of water in three vessels A, B and C are EA, EB and EC respectively and EA > EB > EC. Arrange the temperatures, TA, TBand TC of water in the three vessels in increasing order.
15. Why do solids have a regular geometrical shape?
16. Why are gases compressible but not liquids?
17. Can a rubber band change its shape on stretching? Is it a solid?
18. Why steam at 100°C is better for heating purposes than water at 100°C?
19. Why does the temperature of a substance remain constant during its melting point or boiling point?
20. What do you understand by the term ‘latent heat of fusion’? How much is the latent heat of fusion of ice?
Multiple Choice Questions
Which of the following 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
Ila 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
The property of 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
During summer, water kept in an earthen pot becomes cool because of the phenomenon of
(a) diffusion
(b) transpiration
(c) osmosis
(d) evaporation
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
Choose the correct statement from the following:
(a) Conversion of solid into vapour without passing through the liquid state is called vapourisation.
(b) Conversion of vapour into solid without passing through the liquid state is called sublimation.
(c) Conversion of vapour into solid without passing through the liquid state is called freezing.
(d) Conversion of solid into liquid is called sublimation.
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
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)
The boiling point of water at sea level is
(a) 0°C
(b) 273 K
(c) 373 K
(d) 273°C
Which of the following has the strongest interparticle forces at room temperature?
(a) Oxygen
(b) Water
(c) Bromine
(d) Iron
Extra Questions
1. How can you change a saturated solution to an unsaturated solution without adding any more solvent to it?
2. Sucrose (sugar) crystals obtained from sugarcane and beetroot are mixed together. Will it be a pure substance or a mixture? Give reasons for the same.
3. Based on which factor a solution is said to be diluted, concentrated or saturated?
4. Identify solute and solvent in ‘tincture of iodine’.
5. What is mass per cent of a solution?
6. What are the two components of a colloidal solution?
7. In what respect does a true solution differ from a colloidal solution?
8. Two liquids ‘A’ and ‘B’ are miscible with each other at room temperature. Which separation technique will you apply to separate the mixture of ‘A’ and ‘B’ if the difference in their boiling points is 27°C?
9. Define crystallisation.
10. Why is crystallisation technique considered better than simple evaporation to purify solids?
11. Why is water called universal solvent?
12. Which of the following are physical changes?
Melting of iron metal, rusting of iron, bending of iron rod, drawing a wire of iron metal.
13. Name two elements which exist in liquid state at room temperature.
14. An unknown substance ‘A’ on thermal decomposition produces ‘B’ and ‘C’. What is ‘A’—an element, a compound or a mixture?
15. Identify the elements from the following substances: sulphur, brine, hydrochloric acid, water, neon, paper, sugar.
16. ‘Sea water can be classified as homogeneous as well as heterogeneous mixture.’ Comment.
17. Why is it not possible to distinguish particles of a solute from the solvent in solution?
18. Explain why particles of a colloidal solution do not settle down when left undisturbed, while in the case of a suspension they do.
19. Identify colloids and true solutions from the following:
Pond water, fog, aluminium paint, vinegar and glucose solution.
20. What do you understand by the term distillation? Give its one application.
Multiple Choice Questions
Rusting of a particle 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
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
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
Blood and sea water are
(a) both mixtures
(b) both are compounds
(c) blood is a mixture whereas sea water is a compound
(d) blood is a compound and sea water is a mixture
Sol and gel are examples of
(a) Solid-solid colloids
(b) Sol is a solid-liquid colloid and gel is liquid solid colloid
(c) Sol is solid-solid colloid and gel is solid-liquid colloid
(d) Sol is a liquid-solid colloid and gel is a solid-liquid colloid
In a water-sugar solution
(a) water is solute and sugar is solvent
(b) water is solvent and sugar is solute
(c) water is solute and water is also solvent
(d) none of these
Boron and carbon are
(a) metalloids
(b) metalloid and non-metal respectively
(c) metal
(d) non-metal and metalloid respectively
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)
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)
Which of the following methods would you use to separate cream from milk?
(a) Fractional distillation
(b) Distillation
(c) Centrifugation
(d) Filtration
Extra Questions
1. Name two scientists who established the laws of chemical combination?
2. Give an example of a triatomic molecule of an element.
3. What is atomicity.
4. Write the atomicity of the following molecules:
a. Sulphur
b. Phosphorus
5. What is an ion? Give one example.
6. Give one word for the following:
a. A group of atoms carrying a charge
b. Positively charged ion
7. The atomic number of three elements A, B and C are 9, 10 and 13 respectively. Which of them will form a cation?
8. What is wrong in saying ‘one mole of nitrogen’?
9. ‘Dalton’s atomic theory is contradicted by the formula of sucrose (C12H22O11).’ Justify the statement.
10. How many times heavier is one atom of carbon than one atom of oxygen?
11. Give an example to show law of conservation of mass applies to physical changes also.
12. Differentiate between the actual mass of a molecule and gram molecular mass.
13. Calculate the formula mass of sodium carbonate (Na2CO3.10H2O).
14. Calculate the mass of one atom of hydrogen atom.
15. Does the solubility of a substance change with temperature? Explain with the help of an example.
16. Calculate the mass percentage of oxygen present in the following compounds and state the law of chemical combination associated. Given, H = 1, O = 16.
(i) Water (H2O)
(ii) Hydrogen peroxide (H2O2)
17. Calculate the molecular mass of the following:
(a) H2CO3
(b) C2H5OH
(C) MgSO4
18. Ram took 5 moles of carbon atoms in a container and Krishna also took 5 moles of sodium atoms in another container of same weight.
a. Whose container is heavier?
b. Whose container has more number of atoms?
19. Calcium chloride when dissolved in water dissociates into its ions according to the following equation.
CaCl2 (aq) → Ca2+ (aq) + 2Cl– (aq)
Calculate the number of ions obtained from CaCl2 when 222 g of it is dissolved in water.
20. A silver ornament of mass ‘m’ gram is polished with gold equivalent to 1% of the mass of silver. Compute the ratio of the number of atoms of gold and silver in the ornament.
Multiple Choice Questions
The chemical symbol for sodium is (a) So
(b) Sd
(c) NA
(d) Na
Which of the following would weigh the highest?
(a) 0.2 mole of sucrose (C12H22O11)
(b) 2 moles of CO2
(c) 2 moles of CaCO3
(d) 10 moles of H2O
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
The relative molecular mass of Na2S2O3.5H2O is
(a) 250 amu
(b) 250 g
(c) 248 amu
(d) 248 g
Which of the following has maximum number of atom?
(a) 18 g H2O
(b) 18 g of O2
(c) 18 g of CO2
(d) 18 g of CH4
Percentage of calcium in calcium carbonate is
(a) 40
(b) 30
(c) 48
(d) 36
Which has maximum number of molecules?
(a) 1 g of CO2
(b) 1 g of N2
(c) 1 g of H2
(d 1 g of CH4
The value of Avogadro’s constant is: (a) 6.0 × 1024
(b) 6.01 × 1022
(c) 6.022 × 1023
(d) 6.022 × 10-23
How many times an atom of sulphur is heavier than an atom of carbon?
(a) 32 times
(b) 12 times
(c) 8/3 times
(d) 12/32 times
Which of the following represents 12 u?
(a) Mass of 1 hydrogen atom
(b) Mass of C-12 atom
(c) Mass of 0-16 atom
(d) 1/12th of mass of C-12 atom.
1. Which subatomic particle is absent in an ordinary hydrogen atom?
2. J. Chadwick discovered a subatomic particle which has no charge and has mass nearly equal to that of a proton. Name the particle and give its location in the atom.
3. Electron attributes negative charge, protons attribute positive charge. An atom has both but why there is no charge?
4. Is it possible for the atom of an element to have one electron, one proton and no neutron? If so, name the element.
5. Write the electronic configuration of an element whose atomic number is 13.
6. What do you understand by ground state of an atom?
7. What is the maximum number of electrons which can be accommodated in ‘N’ shell?
8. Write the correct representation of an element ‘X’ which contains 15 electrons and sixteen neutrons.
9. What will be the valency of an atom if it contains 3 protons and 4 neutrons?
10. One electron is present in the outermost shell of the atom of an element X. What would be the nature and value of charge on the ion formed if this electron is removed from the outermost shell?
11. In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting requisite number of electrons, then what would be the charge on the ion so formed ?
12. Which isotope of hydrogen is present in heavy water?
13. Chemical formula of a metal sulphate is MSO4. What will be the formula of its chloride?
14. Valency of an element X is 3. Write the chemical formula of its oxide.
15. The atomic number of calcium and argon are 20 and 18 respectively, but the mass number of both these elements is 40. What is the name given to such a pair of elements?
16. How do you know that nucleus is very small as compared to the size of atom?
17. Write two characteristics of the canal rays.
18. The atomic number of lithium is 3. Its mass number is 7.
a. How many protons and neutrons are present in a lithium atom?
b. Draw the diagram of a lithium atom.
19. Write the formula of the compounds formed by the following ions.
(a) Mg2+ and S2-
(b) Cu2+ and OH
20. What is the gold foil experiment? Name the scientist who performed this experiment. Write the conclusions and shortcomings of Rutherford’s model of atom.
21. What is the maximum number of electrons which can be accommodated in ‘M’ shell?
22. Why atom is nuetral in nature?
23. Write the correct representation of an element ‘X’ which contains 3 electrons and 4 neutrons.
24. What will be the valency of an atom if it contains 15 protons and 16 neutrons?
25. One electron is present in the outermost shell of the atom of an element X. What would be the nature and value of charge on the ion formed if this electron is removed from the outermost shell?
26. Which isotope of hydrogen is present in heavy water?
27. Chemical formula of a metal sulphate is MSO4. What will be the formula of its oxide?
28. Will 35Cl and 37Cl have different valencies? Justify your answer.
29. Write the electronic configuration of a positively charged Magnesium ion (Mg2+). Atomic number of magnesium is 12.
30. Why do inert gases have a zero valency?
31. Why do isotopes show similar chemical properties?
32. An atom of an element has electronic configuration 2,8,6.
a. what will be it's atomic number?
b. write valency.
33. What is an octate? Why would atoms want to complete their octate?
34. Why did Rutherford select a gold foil for his experiment?
35. Which subatomic particle determines the mass of an atom?
Multiple Choice Questions
Which of the following correctly represents the electronic distribution in the Mg atom?
(a) 3, 8, 1
(b) 2, 8, 2
(c) 1, 8, 3
(d) 8, 2, 2
Rutherford’s ‘alpha (α) particles scattering experiment’ resulted in the discovery of
(a) electron
(b) proton
(c) nucleus in the atom
(d) atomic mass
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)
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
(ii) Bohr’s atomic model
(a) (i), (ii) and (iii)
(b) (ii), (iii) and (i)
(c) (ii), (i) and (iii)
(d) (iii), (ii) and (i)
The ion of an element has 3 positive charges. Mass number of the atom is 27 and the number of neutrons is 14. What is the number of electrons in the ion?
(a) 13
(b) 10
(c) 14
(d) 16
The first model of an atom was given by
(a) N. Bohr
(b) E. Goldstein
(c) Rutherford
(d) J.J. Thomson
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.
Which of the following statements about Rutherford’s model of atom are correct?
(i) Considered the nucleus as positively charged.
(ii) Established that the a-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)
How many electrons are present in M-shell of an element with atomic number 20?
(a) 5
(b) 8
(c) 12
(d) 18
An alpha particle is also known as:
(a) subatomic particle
(b) an unionised helium atom
(c) a neutral particle
(d) a doubly-charged helium ion