InterviewSolution
Saved Bookmarks
InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 1651. |
Give reasons : Hydrogen is not used in balloons inspite of being the lightest gas. |
| Answer» SOLUTION :HYDROGEN is INFLAMMABLE. | |
| 1652. |
Give reasons for the following observation: The smell of hot sizzling food reaches you several metres away. But to get the smell from cold food you have to go close. |
| Answer» SOLUTION :The smell of food reaches us by the PROCESS of DIFFUSION of gases (released by the food) into the air. The rate of diffusion of hot gases into air is faster than that of cold gases. So, the smell of hot SIZZLING food reaches us quickly even when we are several METRES away because the rate fo diffusion of hot gases (released by the hot sizzling food) is much faster than the rate of diffusion of cold gases released by the cold food. | |
| 1653. |
Give reasons for the following observations (a) The smell of lighted incrense stick spreads several metres away. (b) A liquid has a fixed volume but not a fixed shape. (c ) Ice floats over water. (d) A wooden table is called a solid at room temperature. |
| Answer» SOLUTION :(a) This happens because of DIFFUSION. | |
| 1654. |
Give reasons for the following observations (a) The smell of lighted incense stick spreads several metres away. (b) A liquid has a fixed volume but not a fixed shape. (c ) Ice floats over water. |
| Answer» SOLUTION :(a) This happens because of DIFFUSION. | |
| 1655. |
Give reason for the following observations. (a)Naphthalene balls disappear with time without leaving any solid. (b) We can get the smell of perfume sitting several metres away. |
|
Answer» Solution :(a) Naphthalene is a volatile SOLID organic compound which can undergo sublimation (change from solid state directly into vapour state).The solid naphthalene balls keep subliming slowly (keep CHANGING into VAPOURS slowly). And after a certain time, the naphthalene balls sublime completely forming naphthalene vapours (which go into air), and hence they disappear without leaving any solid residue. (b)We can get the smell of perfume sitting SEVERAL metres away due to the diffusion of perfume vapours into air. This can be explained as follows : Perfume is a volatile liquid. When liquid perfume is applied by a person, it quickly changes into vapours (or gas). The perfume vapours move very rapidly in all directions in air, mix up with air particles and SPREAD in the air by diffusion. When this air containing perfume vapours reaches several metres away, we can smell the perfume. |
|
| 1656. |
Give reasons for the following observation: The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food yhou have to go close. |
| Answer» Solution :The smell (aroma) of hot SIZZLING food reaches us several metres away because the PARTICLES of hot food have more kinetic energy due to HIGH TEMPERATURE and they diffuse faster in air.The particles of cold food diffuse very slowly in air, THEREFORE we have to go close to the cold food to get the smell. | |
| 1657. |
Give reasons for the following: (a) Petroleum deposits are always associated with a layer of natural gas The volatile products obtained by distillation of coal are passed through water. ( c) A mixture of acetylene and oxygen is used ofr welding metals. ( d) Anthratic coal is of better quality than bituminous coal. ( e) It is possible to perpare an alkane with one car-bon atom from a carboxylic acid with two carbon atoms. |
|
Answer» Solution :(a) The most volatile HYDROCARBONS under the earth s crust vaporise under high temperatureand pressure conditions and form a layer of natural gas (b) The volatile products obtained by distillation of coal may contain some water soluble gases such as `NH_3` as impurities. THEREFORE, they are passed through water to remove the volatile impurities (c) Acetyleneu ndergoes combustion to produce large amount of heat. A mixture of acetylene and oxygen produce a tempereture of `3800^@C` which is higher than the meting points of metals . Therefore , it is used for welding purpose (d) Anthracite coal contains 90 per CENT and 10 per cent of other components such as sulphur or nitrogen. BITUMINOUS coal contains 70 per cent of other components such as sulphur and nitrogen .As sulphur and nitrogen contribute much to the air water POLLUTION anthracite is colsodered as a better type of coal Decarboxylation involves removal of `CO_2` and resultant reducation of atoms from the parent corboxylic acid . Hence alkane with one carbon atom is prepared from carboxylic acid with two carbon atoms |
|
| 1658. |
Give reasons for the following: (a) Isotopes of an element are chemically similar. , (b) An atom is electrically neutral (c ) Nobles gases show least reactivity , (d) Nucleus of an atom is heavy and positively charged (e ) Ions are more stable than atoms. |
|
Answer» Solution :(a) Isotopes ofan element have same atomic number as well as electronic distribution . Since the chemical properties of the element are related to their electronic distribution or configuration the elements with similar configuration have similar properites .Thus the isotopes of an element are chemically similar . (b) In an atom the number of protons in the nucleus ISTHE equal to the number of electrons in the extra nuclear portion .since each proton and each electron has the same CHARGE but with opposite magnitude atom is therefore electically neutral . (c ) The atoms of the NOBLE GAS elements have complete outermost electron shells .With the exception of helium (He) which has two electrons in its only shell (k shell )the rest of the members of the family have eight electrons in their outermost or valence shell. This means that atoms of these elements have no urge to take part in chemical combination or they are least reactive in nature. (d) for answer consult section 4.4 (e ) When an atom changs inn to ion (cation or anion) the valence shell of the ion has a complete octert (i.e it has eight electrons in the outermost or valence shell ) .In some ions the valence shell is K shell and it has only two electrons (e.g `Li^(+)` ion or `H^(-)` ion ) The ions are therefore , quite stable in nature. |
|
| 1659. |
Give reasons for the following : (a) A liquid generally flows easily. (b) Ice at 0^(@)C appears colder in the mouth than water at 0^(@)C. (c ) Doctors advise to put strips of wet cloth on the forehead of a person having high fever. |
|
Answer» Solution :(a) The intermolecular forces in a liquid are weak. Its molecules are able to slide over ONE another and liquid GENERALLY flows EASILY. (b) Latent heat of fusion of ice is QUITE high. In the mouth, ice absorbs this heat and melts. That is why ice at `0^(@)C` gives more cooling sensation in the mouth than water at the same temperature. (c ) As water evaporates from the strips of wet cloth placed on the forehead of a person, it absorbs heat from the body. The body temperature gets lowered and the person get some relief from FEVER. |
|
| 1660. |
Give reasons : A white powder is formed on the surface of washing soda crystals when left exposed to atmosphere. |
| Answer» SOLUTION :LOOSE WATER of CRYSTALLISATION (EFFLORESCENCE) | |
| 1661. |
Give reasons. A gas fills completely the vessel in which it is kept. |
| Answer» Solution :The force of attraction between particles of gas in NEGLIGIBLE. Because of this, particles of gas MOVE in all DIRECTIONS. THUS a gas fills the vessel COMPLETELY in which it is kept. | |
| 1662. |
Give reasons. A gas exerts pressure on the walls of the container. |
| Answer» Solution :Particles of gas move randomly in all DIRECTIONS at HIGH speed. As a RESULT, the particles HIT each other and ALSO hit the walls of the container with a force. Therefore, gas exerts pressure on the walls of the container. | |
| 1663. |
Give reasons: a. A gas fills completely the vessel in which it is kept. b. A gas exerts pressure on the walls of the container. c. A wooden table should be called a solid. d. We can easily move our hand in air but to do the same through a solid block of wood we need a karate expert. |
|
Answer» Solution :a. The force of ATTRACTION between the particles of GAS is very less. They have high kinetic energy. So the particles of gas ove in alldirections and fill the vessel completely in which it is KEPT. b. The particles of gas are moving randomly at high speed in al directions due to high kinetic energy. They vibrate constantly and collide with the walls of the container. THe impact of force of the moving particles exert pressure on the walls of the container. c. THe particles o wooden table are very CLOSE to each other. It cannotbe compressed and retain shape even if the force is APPLIED to it. It has all the characteristics of a solid. Therefore, a wooden table should be called a solid. d. The particles of air have negligible force between them. There is much intermolecular space between the particles of air. So a very small exteral forc ecan separate the particles of air. Block of wood is solid. The force of attraction between the particles so wood is very high. Therefore and extremely large amount of external force is required to pass through the block of wood. |
|
| 1664. |
Give reasons (a) A gas fills completely the vessel in which it is kept. (b) A gas exerts pressure on the walls of the container. (c) A wooden table should be called a solid. (c) We can easily move our hand in air but to do the same through a solid blocked of wood. we need a karate expert. |
|
Answer» Solution :(a) The particles of a gas have high kinetic energy and negligible forces of attraction amongst them. Due to this the particles of a gas are CONSTANTLY moving with high speeds in all the directions and the gas completely fills the vessel in which it is KEPT. (b)Because of high kinetic energy and negligible forces of attraction, the particles of a gas move with high speeds in all directions. When the FAST moving gas particles hit the walls of its container from inside, they exert a pressure (CALLED gas pressure). Thus, the pressure exerted by a gas is due to the constant collisions of the fast moving gas particles against the inner walls of the container. (c ) A wooden table is a rigid object having a definite shape and a definite volume. Since a wooden table has these basic characteristics of solid state (rigidity, definite shape and definite volume), it should be calleda solid. (d) Air is a gas (or a mixture of gases) whose particles are very far APART and there are very weak forces of attraction between them. The extremely weak forces between particles of air can be overcome easily due to which we can easily move our hand in air. On the other hand, the particles of a solid block of wood are very closely packed and there are very strong forces of attraction between the particles of wood. It needs a huge outside force to overcome the strong interparticle attractions of a block of wood and break it apart by moving hand which only a karate expert can apply. |
|
| 1665. |
Give reason for the following : (a) Gases fill up completely the vessel in which they are kept. (b) Gases exert pressure on the walls of the containing vessel. |
|
Answer» Solution :(a) Particles constituting GASES are very FAST MOVING and diffuse at a fast speed. They therefore, readily FILL up the vessel completely in which these are kept. (b)j Particles of gases COLLIDE against the walls of the containing vessel and impart momentum to them. This is responsible for the pressure of the gas. |
|
| 1666. |
Give one similarity and one dissimalarity between a liquid and a gas. |
|
Answer» SOLUTION :SIMILARITY: Liquids and gases are are fluids are the take the SHAPE of the container. Dissimilarity: Gases are highly compressible WHEREAS liquids are not. Liquids have definite volume, gases do not have definite volume. |
|
| 1667. |
Give one example of water undergoing a physical change and one where it undergoes a chemical change . |
| Answer» Solution :BOILING of WATER is a physical CHANGE , and electrolysis of water is a CHEMICALCHANGE . | |
| 1668. |
Give one example of Tyndall effect in day-to-day life. |
| Answer» SOLUTION :Scattering of LIGHT by dust particles suspended in AIR is an EXAMPLE of Tyndall effect in day-to-day LIFE. | |
| 1669. |
Give one example each of polyatomic element and polyatomic ion. |
|
Answer» Solution :Poly atomic ELEMENT : phosphorous `(P_(4))` Polyatomic ION: `(SO_(4)^(2-))` |
|
| 1670. |
Give IUPAC names for the following |
|
Answer» `H_3C-underset(CH_(3))underset(|)"CH"-CH_2-CH=CH_2` |
|
| 1671. |
Give information about isotopes. |
|
Answer» Solution :(1) Isotopes have same atomle number but different mass NUMBERS, i.e.. number of protons are same but the number of neutrons are different. (2) The chemical PROPERTIES of isotopes are similar but THELR physical properties are different. e.g. chlorine has TWO isotopes with atomic number 17, but mass numbers as 35 and 37. |
|
| 1672. |
Give four examples each for reversible and irreversible reactions. |
| Answer» | |
| 1673. |
(a) What is a mixture? Give to examples of mixtures. (b) What is meant by (i) homogeneous mixtures, and (ii) heterogeneous mixtures? Give two example os homogeneous mixtures and two of heterogenous mixtures. |
| Answer» SOLUTION :The TWO examples are (a) a MIXTUREOF soil and water , and ( b) a mixtureof IRON filings and sulphure . | |
| 1674. |
Give examples of polyatomic ions. |
| Answer» Solution :Ammonium : `NH_(4)^(+)`, Carbonate: `CO_(3)^(2-)`, Hydrogen carbonate : `HCO_(3)^(-)`, Phosphate : `PO_(4)^(3-)` are the examples of polyatomic ions. | |
| 1675. |
Give differences between reversible and irreversible reactions. |
| Answer» | |
| 1676. |
Give definition of theValency |
| Answer» SOLUTION :The combining CAPACITY of an ELEMENT is known as its valency. | |
| 1677. |
Give definition of thePolyatomic ion |
| Answer» Solution :The GROUP of ATOMS which acts as an ion, is CALLED POLYATOMIC ion. | |
| 1678. |
Give definition of theMolecule |
| Answer» SOLUTION :The SMALLEST particle of an ELEMENT or a COMPOUND is called molecule. | |
| 1679. |
Give definition of the Molecular mass |
| Answer» Solution :The SUM of the atomic MASSES of all ATOMS in a MOLECULE of the substance is called molecular mass. | |
| 1680. |
Give definition of the Molar mass |
| Answer» SOLUTION :The mass of 1 mole of ATOM of the substance in gram is called MOLAR mass. | |
| 1681. |
Give definition of the following : Unsaturated solution |
| Answer» Solution :A solution in which the AMOUNT of solute is less than the saturation LEVEL is CALLED an UNSATURATED solution. | |
| 1682. |
Give definition of the following : Suspension |
| Answer» Solution :A heterogeneous SYSTEM in which SOLIDS are dispersed in LIQUIDS is CALLED suspension. | |
| 1683. |
Give definition of the following : Solid sol |
| Answer» Solution :A COLLOID in which both the dispersed phase and dispersing medium are LIQUID is CALLED solid sol. | |
| 1684. |
Give definition of the following : Homogeneous mixture |
| Answer» SOLUTION :A MIXTURE which contains uniform composition is called HOMOGENEOUS mixture. | |
| 1685. |
Give definition of the following : Saturated solution |
| Answer» SOLUTION :At any particular temperature, a solution that has DISSOLVED as much solute as it is CAPABLE of dissolving is CALLED a saturated solution. | |
| 1686. |
Give definition of the following : Crystallisation |
| Answer» SOLUTION :The process used to SEPARATE PURE SOLID SUBSTANCE from the solution in the form of crystals is called crystallisation. | |
| 1687. |
Give definition of the following : Emulsion |
| Answer» SOLUTION :A COLLOID in which both the DISPERSED phase and DISPERSING medium are liquid is CALLED emulsion. | |
| 1688. |
Give definition of the following : Pure substance |
| Answer» SOLUTION :A substance MADE from same type of PARTICLES is called pure substance. | |
| 1689. |
Give definition of the following : Concentration of the solution |
| Answer» SOLUTION :The amount of solute present in a GIVEN amount (mass or VOLUME) of solution is CALLED the CONCENTRATION of the solution. | |
| 1690. |
Give definition of the following : Colloid |
| Answer» SOLUTION :A solution in which the SOLUTE substance is in dispersed phase in the solvent is called COLLOID. | |
| 1691. |
Give definition of the following : Alloy |
| Answer» Solution :A MIXTURE of TWO or more METALS or a metal and a non-metal is CALLED an alloy. | |
| 1692. |
Give definition of the following : Compound |
| Answer» Solution :A SUBSTANCE formed by the chemical COMBINATION of TWO or more elements in a fixed PROPORTION is called a COMPOUND. | |
| 1693. |
Give definition of the following : Aerosol |
| Answer» Solution :A colloid in which the DISPERSED PHASE is either LIQUID or solid and dispersing medium is GAS, is called aerosol. | |
| 1694. |
Give definition of theAtomicity |
| Answer» Solution :The NUMBER of atoms CONSTITUTING a MOLECULE is KNOWN as its atomicity. | |
| 1695. |
Give definition of the Atomic mass |
| Answer» Solution :The mass of the ATOM as compared to `(1)/(12)`TH mass of ONE carbon-12 atom is called ATOMIC mass. | |
| 1696. |
Give brief description of mendeleev 's periodic table |
| Answer» | |
| 1697. |
Give balanced equations to show the preparation of hydrogen by the following: steam |
| Answer» SOLUTION :`Zn+H_(2)OtoZnO+H_(2)` | |
| 1698. |
Give balanced equations to show the preparation of hydrogen by the following: nitric acid |
| Answer» SOLUTION :`Mg+underset(("V.dilute"))(2HNO_(3))toMg(NO_(3))_(2)+H_(2)` | |
| 1699. |
Give balanced equations to show the preparation of hydrogen by the following: iron |
| Answer» SOLUTION :`3Fe+4H_(2)OtoFe_(3)O_(4)+4H_(2)` | |
| 1700. |
Give balanced equations to show the preparation of hydrogen by the following: cold water. |
| Answer» SOLUTION :`2Na+2H_(2)Oto2NaOH+H_(2)` | |