2599 + Interview Questions in Chemistry in Class 9 Page 4 InterviewSolution

151.	What is the mass of (a) 1 moleof nitrogen atoms? (b) 4 moles of aluminium atoms (Atomic mass of aluminium = 27 ?) (C) 10 moles of sodium sulphite (Na_(2)SO_(3)) ?
Answer» Solution :(a) The mass of 1 mole of nitrogen atoms is 14g. (b) The mass of 4 moles of ALUMININUM atoms is `(4x27)=108g`. (C) The mass of 10 moles of Sodium Sulphite `(Na_(2)SO_(3))` is `10x[2x23+32+3x16]g=10x126g=1260g`

Discussion

152.	What is top soil?
Answer» Solution :The TOPMOST layer of the soil is CALLED TOPSOIL or SURFACE soil.

Discussion

153.	When heat is constantly supplied by a burner to boiling water, then the temperature of water during vaporisation :
Answer» rises very slowly rises rapidly until steam is produced FIRST rises and then BECOMES constant does not rise at all Answer :D

Discussion

154.	Write the electronic configuration of the most stable cation of the element having the lowest ionisation potential value and belonging to the 4th peroid justify you answer
Answer» Solution :(i) TREND of IP VALUE along a period (II) trend of ionisaton potential along a period (iii) the group that has elemtns with lowestionisation potential in their respective the PERIODS (iv) electronic configuratioin of the element and cation

Discussion

155.	What are colloids ? Explain why filter paper cannot be used to separate colloids.
Answer» Solution :Colloids are intermediate state of the solution and SUSPENSION. The SIZE of COLLOID particles is between 1 NM and 100 nm. Because of this SMALL size, colloid passes through a filter paper and hence filter paper cannot be used to separate colloids.

Discussion

156.	In which of the following conditions, the distance between the molecules of hydrogen gas would increase ? (i) Increasing pressure on hydrongen contained in a closed container. (ii) Some hydrogen gas leaking out of the container. (iii) Increasing the volume of the contianer of hydrogen gas . (iv) Adding more hydrogen gas to the container without increasing the volume of the container.
Answer» (i) and (III) (i) and (IV) (ii) and (iii) (ii) and (iv). Solution :Both these CONDITIONS WOULD INCREASE the distance in the molecules of hydrogen.

Discussion

157.	Then what about those having the low ionization energy?
Answer» ANSWER :METALS

Discussion

158.	Write the distribution of electrons incarbon and sodium atoms.
Answer» Solution :CARBON (a-6):2(K-shell),4(L-shell) Sodium (=11):2(K-shell),10(L-shell),(M-shell)

Discussion

159.	What are groups and periods in the mordern periodic table ?
Answer» Solution :The horizontal rows are called periods. There are seven periods in the periodic table. Vertical columns in the periodic table STARTING from TOP to BOTTOM are called groups. There are 18 groups in the periodic table.

Discussion

160.	What do you think would be the observation if the alpha-particle scattering experiment is carried out using a foil of a metal other than gold ?
Answer» Solution :If the metal is a heavey one like gold(e.g silver , platimum etc) similar results will be obtained .However if the meta is quite light (e.g sodium magnesium etc) it is just POSSIBLE that the fast moving and massive `alpha` particles (4`mu` MASS) may push the nucleus aside and pas through with slight deviation only

Discussion

161.	Which of the followingrepresents an element ?
Answer» BRASS STAINLESS stell arsenic SILICA ANSWER :C

Discussion

162.	The salt which is deliquescent : Washing soda;Glaubers salt ;Iron (III) chloride;Sodium chloride;
Answer» WASHING soda Glaubers salt Iron (III) chloride Sodium chloride Answer :C

Discussion

163.	What are negative catalysts ? Give an example.
Answer»

Discussion

164.	What is the mass of (a) i mole of nitrogen atoms? (b) 4 moles of aluminium atoms (Atomic mass of aluminium = 27)? (c) 10 moles of sodium sulphite (Na_(2)SO_(3)) ?
Answer» Solution :(a) Mass of 1 mole of NITROGEN = 14 g (b) Mass of L mole of ALUMINIUM atoms = 27 g `:.` mass of 4 moles of aluminium atoms = `4 xx 27 = 108` g (c) Mass of 1 mole of `Na_(2)SO_(3) = (2 xx 23) + (1 xx 32) + (3 xx 16)` = 46 + 32 + 48 = 126 g `:.` mass of 10 moles of `Na_(2)SO_(3) = 10 xx 126 = 1260 g`

Discussion

165.	Though the kinetic energy of electrons decreases with an increase in the distance from the nucleus, the potential energy of the electron increases. How do you account for this ?
Answer» Solution :The kinetic energy of an electron is proportional to its velcity. With the increase in DISTANCE from the nucleus , the VELOCITY of the electron decreases as the electron has to overcome a lesser nuclear force of attraction. An electron LOSES its potential energy when it approaches TOWARDS an atom that is a nucleus because it WORKS towards the force of attraction during this process. Hence, the potential energy of the electron decreases with decrease in distance between the nucleus and the electron and increases with increase in distance between the nucleus and electron.

Discussion

166.	Though they are found rare, they have many uses. Justify this statement.
Answer» Solution :Helium, Neon, Argon, Kryton, Xenon and Radon are called the Noble or rare GASES and are placed in group 18 in the periodic table. They are monoatomic and do not react with other substances EASILY. Though these gases are chemically inert, they have stable ELECTRONIC structures which are difficult to change. Their USES are as follows- (i) Helium has a very low density and used for filling weather ballon. (ii) Neon gas is used in discharge lamps. (iii) Argon is filled in ELECTRICAL bulbs to prevent evaporation of the filament. (iv) Radon is a radioactive gas.

Discussion

167.	What is the colour of the precipitate formed ?
Answer» ANSWER :PALE YELLOW

Discussion

168.	There are three shells in the atom of element 'X', 6 electrons are present in its outermost shell. In which group is this element included?
Answer» ANSWER :16

Discussion

169.	There are three shells in the atom of element 'X', 6 electrons are present in its outermost shell. In which period does this element belong?
Answer» ANSWER :3

Discussion

170.	What are drugs? What ar their characteristics?
Answer» Solution :The chemicals used for treating DISEASES are termed as DRUG. Characteristics of drugs: A drug must possess the following: a. It should not be toxic b. It should not CAUSE any side effects. c. It should not affect the receptor tissue d. It should not affect the normal physiological activities e. It should be EFFECTIVE in its ACTION.

Discussion

171.	What would you observe when (a) a saturated solution of potassium chloride prepared at 60^(@)C is allowed to cool at room temperature? (b) an aqueous sugar solution is heated to dryness? (c) a mixture of iron filings and sulphur powder is heated strongly?
Answer» Solution :(a) Upon cooling, crystals of potassium chloride would SEPARATE. (B) Initially, entire water SLOWLY gets removed.Upon further heating, sugar gets charred and burning smell will be noticed. (c ) Iron SULPHIDE is formed as a greyish black RESIDUE.

Discussion

172.	What is the mass of proton as compared to electron ?
Answer» SOLUTION :MASS of PROTON was found approximately 2000 times (1840 times) as that of electron. It is `1.67xx10^(-24)g` approximately.

Discussion

173.	When does the pressure of the gas increase?
Answer» Solution :When the volume of the GAS decreases, the gas gets COMPRESSED The PARTICLES of the gas have only lesser space to move AROUND. So the particles start hitting o the walls of the container and the pressure of the gas increases.

Discussion

174.	What are the characteristics of transition elements?
Answer» ANSWER :

Discussion

175.	While doing an experiment to determine the melting paint of ice state the role of glass stirrer and mention the correct position of bulb of the thermometer.
Answer» Solution :Stirring the contents of the beker with a glass stirrer KEEPS the heating uniform .The position of the THERMOMETER should be such the bulb is just TOUCHING the ice cubes .For details CONSULT text part (PAGE 41)

Discussion

176.	The substances that cause pollution are called poisons.
Answer» ANSWER :F

Discussion

177.	The value of the Avogadro constant is
Answer» `6.022 xx 10^(24)` `6.022 xx 10^(22)` `60.22 xx 10^(23)` `6.022 xx 10^(23)` ANSWER :D

Discussion

178.	Which fundamental particle was discovered by J. J. Thomson ?
Answer» SOLUTION :Electron, the FUNDAMENTAL PARTICLE, was discovered by J. J. THOMSON.

Discussion

179.	What are alpha-particles made-up of ?
Answer» 2 ELECTRONS and 2 protons 2 protons and 2 NEUTRONS 2 electrons and 2 neutrons Helium atom Solution :FORMULAOF `alpha`-particle : `""_(2)^(4)He^(+)`.

Discussion

180.	Which of the following substance acts as a pure substance ?
Answer» SODIUM chloride Cold drinks Aerosol Soil Answer :C::D

Discussion

181.	Which of the following statements about theanode rays is (are) wrong ?
Answer» The anode rays originate from the cathode . The anode rays are deflected TOWARDS the NEGATIVE plate of an electric field. The e/m ratio for the particles of the anode rays is the same for all gases used in the discharge tube . The anode rays can rotate a light paddle wheel placed in their path. ANSWER :C

Discussion

182.	What is the shape of the meniscus observed when water and mercury are taken in two differentcapillary tubes and why ?
Answer» Solution :Mercury shows a convex meniscus as it has higher COHESIVE forces than adhesive forces with glass. Water, on the other hand, shows a CONCAVE meniscus as the adhesive forces between water and glass are higher than the cohesive forces between water MOLECULES.

Discussion

183.	Which of the following figures do not denote the atom truely as per Bohr's model of atom?
Answer» (i) and (II) (ii) and (III) (ii) and (IV) (i) and (iv) ANSWER :A::D

Discussion

184.	Total number of groups?
Answer» ANSWER :18

Discussion

185.	What type of Mixtures are seperated by technique of crystilisation ?
Answer» SOLUTION :The crystallization METHOD is USED to purify solids.

Discussion

186.	Which of the following is a liquid-liquid colloid ?
Answer» Fog Butter Milk Milk of MAGNESIA

Discussion

187.	Which of the following parameters remains constant in a chemical reaction ?
Answer» TOTAL MASS Total volume Mass of the reactants None of the above Solution :Total mass

Discussion

188.	What is electroplating? Why is it done?
Answer» Solution :The process of depositing a thin layer of one METAL over ANOTHER metal by the process of electrolysis is called electroplating. It is done to PROTECT the metal from corrosion. For example, metals like iron are electroplated with TIN, NICKEL or chromium to protect from rusting.

Discussion

189.	What is the physical state of water at: a. 250^(@)Cb. 100^(@)C ?
Answer» Solution :(a) The BOILING point of water is `100^(@)C`. So, the physical state of water at a temperature of `250^(@)C` (which is much above its boiling point) will be 'gaseous state'. (b)The physical state of water at its boiling point temperature of `100^(@)C` will be both 'liquid state' as well as 'gaseous state'. This is because at its boiling point (of `100^(@)C`), the liquid state of water STARTS CHANGING into its gaseous state (steam).

Discussion

190.	Whne canal rays experiment is conducted with hydrogen gas, scientists were found to give particles with different (e)/(m) values. Justify.
Answer» SOLUTION :(i) e/m depends on NUMBER of protons and NEUTRONS (ii) existence of ISOTOPES (iii) variation in e/m for isotopes.

Discussion

191.	What happens when temperature of a reaction mixture increases from 20^(@)C " to " 60^(@)C ?
Answer» the RATE of the reaction increases and rate CONSTANT decreases the rate of reaction and the rate constant, decreases the rate of reaction REMAINS UNCHANGED and rate constant increases both rate and rate constant of the reaction increases Answer :D

Discussion

192.	Two solid non-metals X and Y are taken which are used for purpose of vulcanisation of rubber and for use in sugar industry , respectively.A mixture of X,Y, and Z, which is a salt of an alkali metal of corresponding 'ic' acid of nitrogen cam explode on heating even in the absence of oxygen. Justify.
Answer» Solution :(i) identification os X,Y and salt Z (II) effect of heat on Z. (iii) nature of the PRODUCTS formed (iv) REACTION of the GASEOUS product with X and Y (v) change in pressure and heat CONTENT due to above reactions.

Discussion

193.	Which of the followingare involved in the condensation of water vapour leading to theformation of clouds ?
Answer» Temperature DUST PARTICLES Carbon dioxide OZONE layer ANSWER :A::B

Discussion

194.	Which condition out of the following will increase the evaporation of water ?
Answer» INCREASE in temperature of water Decrease in temperature of water Less exposed surface area of water Adding common salt to water. Solution :Increase in temperature always HELPS in evaporation of a LIQUID.

Discussion

195.	Which of the following is expected to showtyndall effect ?
Answer» a SOLUTION of common salt milk a solution of SODIUMCARBONATE STARCH solution ANSWER :D

Discussion

196.	What are acids?
Answer» Solution :Acids are those with CHEMICAL PROPERTIES that INCLUDES, turning litmus red, neutralizing "ALKALIS, and dissolving some metals, typically, a corrosive or sour-tasting liquid present in curd, fruit juices, vinegar, etc. The word .acid. is derived from the Latin NAME "acidus” which means sour taste.

Discussion

197.	What is an ionic or electrovalent bonus
Answer» Solution :The oppositely charged ions are HELD together by electrostatic FORCE of ATTRACTION which is called IONIC or Electrovalent BOND.

Discussion

198.	What is nucleus in an atom ?
Answer» Solution :The positively charged CENTRAL part of an ATOM is called the nucleus.

Discussion

199.	Two substances, A and B were made to react to form a third substance, A_(2)B according to the following reaction 2A+B to A_(2)B. Which of the following statements concerning this reaction are incorrect ? (i) The product A_(2)B 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.
Answer» (i), (ii) and (iii) (ii), (iii) and (IV) (i), (iii) and (iv) (ii) and (iv). SOLUTION :EXCEPT for (ii) all other STATEMENTS are incorrect.

Discussion

200.	Though there is only one electron in a hydrogen atom, the spectrum of hydrogne contains a number of lines, How do you explain this?
Answer» Solution :(i) BOHR's MODEL of atom (II) relation between energy absorbed and EXCITATION (iii) relation between the path of electron during dedxacitation and energy emitted (iv) relation between energy emitted and spectrum

Discussion

Explore topic-wise InterviewSolutions in .

What is the mass of (a) 1 moleof nitrogen atoms? (b) 4 moles of aluminium atoms (Atomic mass of aluminium = 27 ?) (C) 10 moles of sodium sulphite (Na_(2)SO_(3)) ?

What is top soil?

When heat is constantly supplied by a burner to boiling water, then the temperature of water during vaporisation :

Write the electronic configuration of the most stable cation of the element having the lowest ionisation potential value and belonging to the 4th peroid justify you answer

What are colloids ? Explain why filter paper cannot be used to separate colloids.

Then what about those having the low ionization energy?

Write the distribution of electrons incarbon and sodium atoms.

What are groups and periods in the mordern periodic table ?

What do you think would be the observation if the alpha-particle scattering experiment is carried out using a foil of a metal other than gold ?

Which of the followingrepresents an element ?

The salt which is deliquescent : Washing soda;Glaubers salt ;Iron (III) chloride;Sodium chloride;

What are negative catalysts ? Give an example.

What is the mass of (a) i mole of nitrogen atoms? (b) 4 moles of aluminium atoms (Atomic mass of aluminium = 27)? (c) 10 moles of sodium sulphite (Na_(2)SO_(3)) ?

Though the kinetic energy of electrons decreases with an increase in the distance from the nucleus, the potential energy of the electron increases. How do you account for this ?

Though they are found rare, they have many uses. Justify this statement.

What is the colour of the precipitate formed ?

There are three shells in the atom of element 'X', 6 electrons are present in its outermost shell. In which group is this element included?

There are three shells in the atom of element 'X', 6 electrons are present in its outermost shell. In which period does this element belong?

What are drugs? What ar their characteristics?

What would you observe when (a) a saturated solution of potassium chloride prepared at 60^(@)C is allowed to cool at room temperature? (b) an aqueous sugar solution is heated to dryness? (c) a mixture of iron filings and sulphur powder is heated strongly?

What is the mass of proton as compared to electron ?

When does the pressure of the gas increase?

What are the characteristics of transition elements?

While doing an experiment to determine the melting paint of ice state the role of glass stirrer and mention the correct position of bulb of the thermometer.

The substances that cause pollution are called poisons.

The value of the Avogadro constant is

Which fundamental particle was discovered by J. J. Thomson ?

What are alpha-particles made-up of ?

Which of the following substance acts as a pure substance ?

Which of the following statements about theanode rays is (are) wrong ?

What is the shape of the meniscus observed when water and mercury are taken in two differentcapillary tubes and why ?

Which of the following figures do not denote the atom truely as per Bohr's model of atom?

Total number of groups?

What type of Mixtures are seperated by technique of crystilisation ?

Which of the following is a liquid-liquid colloid ?

Which of the following parameters remains constant in a chemical reaction ?

What is electroplating? Why is it done?

What is the physical state of water at: a. 250^(@)Cb. 100^(@)C ?

Whne canal rays experiment is conducted with hydrogen gas, scientists were found to give particles with different (e)/(m) values. Justify.

What happens when temperature of a reaction mixture increases from 20^(@)C " to " 60^(@)C ?

Two solid non-metals X and Y are taken which are used for purpose of vulcanisation of rubber and for use in sugar industry , respectively.A mixture of X,Y, and Z, which is a salt of an alkali metal of corresponding 'ic' acid of nitrogen cam explode on heating even in the absence of oxygen. Justify.

Which of the followingare involved in the condensation of water vapour leading to theformation of clouds ?

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

Which of the following is expected to showtyndall effect ?

What are acids?

What is an ionic or electrovalent bonus

What is nucleus in an atom ?

Though there is only one electron in a hydrogen atom, the spectrum of hydrogne contains a number of lines, How do you explain this?