2599 + Interview Questions in Chemistry in Class 9 Page 38 InterviewSolution

1851.	Bhavna is a student of class IX in a city school. She has a five year old younger brother Bunty who is very naughty. Bhavna's mother, Mrs. Malikm had purchased a big bottle of nail poslish remover from the market about six months back. She had used less than half of this bottle so far. One day Mrs. Malik left this bottle on the dining table by mistake and went out of the house for some work. In her absence, Bunty opened the half empty bottle of nail polish remover and filled it by adding water in it. When Mrs. Malik came back, she was very angry with Bunty and scolded him for spoiling her expensive bottle of nail polish remover. Mrs. Malik was about to throw away his bottle containing nail polish remover mixed with water when her daughter Bhavna came back from school. She told her problem to Bhavna. Bhavna throught over this problem for a while and said that there was no need to throw away the mixture of nail polish remover and water She told her mother that she could recover pure nail polish remover from this mixture. Next day, Bhavna took the bottle containing this mixture to her school laboratory. With the permission of her teacher, Bhavna set up an apparatus which included a particular type of flask fitted will a tall column. She put the mixture of nail polish remover and water in the flask and heated it gradually. On heating nail polish remover was turned into vapour, which were cooled by a water condenser to obtain pure nail polish remover. Water was left behind in the flask. Mrs. Malik was very happy to get back her nail polish remover. (a) What is nail polish remover ? (b) State whether nail polish remover and water are miscible liquids or immiscible liquids (c) Name the process used by Bhavna for the complete separation of mixture of nail polish remover and water. Also define this process. (d) On what factors does the separation of nail polish remover and water mixture of nail polish remover and water. Also define this process (d) On water factors does the separation of nail polish remover and water mixture by the above process depend ? (e) Name the tall column used in the flask during the separation of a mixture of nail polish remover and water (f) What values are displayed by Bhavna in this episode ?
Answer» Solution :(a) Nail polish remover is an organic liquid called 'acetone' It is a very good solvent (b) Nail polish remover (acetone) and WATER are completely miscible liquids (c) (i) The complete separation of a mixture of nail polish remover (acetone) and water was done by Bhavna by USING the process of fractional distillation (ii) Fractional distillation is the process of SEPARATING two (or more) miscible liquids by distillation (by using a fractionating column), the distillate being collected in fractions bolining at different temperatures. (d) The separation of nail polish remover (acetone) and water depends on the difference in their boiling points (The boling point of acetone is `56^(@)C` whereas that of water is `100^(@)C`) (e) Fractionating column (F) The various values displayed by Bhavna in this episode are (i) Knowledge of separation of a mixture of two miscible liquids (ii) Application in solving real-life problems, and (iii) Desire to help her MOTHER (by preventing wastage of expensive nail polish remover).

Discussion

1852.	Between 1000 litres water and 1000 litres CNG, CNG can be transported ealsily from one palce to another.
Answer» Solution :As the compressibility of gases is HIGHER than that of LIQUDS, large volumes of gas can be COMPRESSED into a SMALL cylinder easily.Hence CNG can be transported easily as compared to WATER.

Discussion

1853.	Batteries that are used mobile phone can be recharged. Likewise, can you recharge the batteries used in watches? Justify your answer.
Answer» Solution :A primary cell cannot be recharged. Watch batteries have a primary cell. In a primary cell, chemical ENERGY is CONVERTED into ELECTRICAL energy when current is drawn from it. Whereas MOBILE PHONES use secondary cells. In secondary cells electrical energy is converted to chemical energy when current is passed through it and chemical energy is converted to electrical energy when current is drawn from it.

Discussion

1854.	Based on separation techniques, complete the following. The first one is done for you.{:(,"Mixture","Type","Separation","Principle"),(,,,"Technique",),(1.,"Alcohol + water","Homogeneous","Frictional","Difference in"),(,,,"distillation","boiling point"),(2.,"Sulphur + carbon disulphide",-,-,-),(3.,"Sand + water",-,-,-),(4.,"Pigments of flower",-,-,-):}
Answer» Solution :2. HOMOGENEOUS, Evaporation, Difference in nature. 3. Hetereogeneous, FILTRATION, Difference in solubility in water 4. Homogeneous, Chromatography, Difference in adsorption of different COMPONENTS.

Discussion

1855.	Barium chloride reacts with sodium sulphate to form barium sulphate and sodium chloride. In an experiment to verify the law of conservation of mass, 20.8 g of barium chloride reacted with 14.2 g of sodium sulphate to form 11.7g of sodium chloride. The amount of barlum sulphate formed in the above reaction will be ....
Answer» 35.0 G 23.7 g 23.3 g 23.0 g Solution :23.3 g

Discussion

1856.	Balance the unbalanced chemical equations.
Answer» ANSWER :`2H_2+O_2rarr2H_2O` `N_2+3H_2rarr2NH_3`

Discussion

1857.	Balance the following equations. N_2 + H_2 rarrNH_3
Answer» ANSWER :`N_2 + 2H_2 rarr2NH_3`

Discussion

1858.	Balance the following equations. H_2 + O_2 rarrH_2O
Answer» ANSWER :`H_2 + O_2 rarrH_2O`

Discussion

1859.	Balance the following chemical equations. SO_2 + O_2 rarr SO_3
Answer» ANSWER :`2SO_2+O_2 RARR 2SO_3`

Discussion

1860.	Balance the following chemical equations. Zn + HCl rarr ZnCl_2 + H_2
Answer» ANSWER :`Zn+2HCl RARR ZnCl_2+H_2

Discussion

1861.	Balance the following chemical equations. Mg + O_2 rarr MgO
Answer» ANSWER :`2Mg+O_2 RARR 2MgO`

Discussion

1862.	B and AI belong to the same group but the nature of oxides formed by them are different wheres Be AI form same type of oxide although they belong to different groups comment
Answer» Solution :(i) position of B,Be,AI in the periodic table (II) comaprison of SIZE and ionsiation POTENTIAL of B,Be and AI (iii) relation between sizeIP and nature of the oxides formed

Discussion

1863.	aX to bY. The initial concentration of X is 0.6 M. After 10 min interval of time the concentration of X and Y are found to be 0.3 M and 0.2 M, respectively. Calculate the stoichiometric coefficients and rate of reaction with respect to X and Y.
Answer» Solution :`AX to bY` `{:(0.6,0,"Initial concentration"),(0.3,0.2M, "Final concentration"):}` `r=(-1)/(a)(Delta[X])/(Delta t)=(1)/(b)(Delta [Y])/(Delta t) implies (-1)/(a)((0.3-0.6))/(10)` `=(1)/(b)((0.2-0.0))/(10)` `implies (0.3)/(a)=(0.2)/(b) implies ` Least POSSIBLE VALUES of a and b are 3 and 2, respecitvely Rate with RESPECT to `X=(Delta[X])/(Delta t)=(0.3)/(10xx60)` =0.0005 mole/`L^(-1) "SEC"^(-1)` Rate with respect to `Y=(0.2)/(10xx60)` `=0.00033 " mole" //L^(-1) "sec"^(-1)`

Discussion

1864.	(a)What do the following observations stand for? (i)2O (ii)3O_(2) (b)Which amongst the following has more number of atoms and how much? (i)11.5g of sodium (ii)15.0g of calcium
Answer» Solution :Gram ATOMIC MASS of sodium (Na)=23g 23g of sodium have atoms=`N_(A)` 11.5g of sodium have atoms `=0.5xxN_(A)=0.5xx6.022xx10^(23)` `=3.011xx10^(23)` Gram atomic mass of calcium (CA)=40g 40g of Calcium have atoms =`N_(A)` 15G of calcium have atoms `=(15)/(40)xxN_(A)=0.375xx6.022xx10^(23)` `=2.258xx10^(23)` 11.5g of sodium has more atoms=`(3.011-2.258)xx10^(23)` `=7.53xx10^(22)"atoms:`

Discussion

1865.	Avogadro constant represents ..................... particles.
Answer» SOLUTION :`6.022xx10^(23)`

Discussion

1866.	Avogadaro's number represents the number of atoms in
Answer» `12 G "of" ""_(C)^(12)C` 320G of Sulphur 32 of of oxygen 1 g of `12_(c)` ANSWER :A

Discussion

1867.	Atoms whose nuclei contain different number of protons but same number of neutrons are called
Answer» ANSWER :Isotpes

Discussion

1868.	Atoms of different elements have the same mass .
Answer» ANSWER :F

Discussion

1869.	Atoms form the compound by combining in proper ratio of small integer number. The smallest part of this compound is called …...... .
Answer» SOLUTION :MOLECULE

Discussion

1870.	Atomicweights of three elements in a doberenier traid are x , 81 and 127 .Find the missing atomic weight
Answer» 104 35 46 23 Answer :B

Discussion

1871.	Atomic number of the isotopes of an element are different
Answer» ANSWER :FALSE

Discussion

1872.	Atomic number and Atomic mass number
Answer» SOLUTION :

Discussion

1873.	Atomic number
Answer» SOLUTION :The NUMBER of protons in neutral ATOM of an element is called atomic number (Z) of an element.

Discussion

1874.	Atomic mass number
Answer» Solution :The sum of NUMBER of protons (p) and number of neutrons (N) PRESENT in the nucleus of an ATOM is called its atomic mass number.

Discussion

1875.	At what temperature in Kelvin scale does water boil? Explain what happens whenwe supply heat energy to water till it changes its state? What is the heat energy called?
Answer» Solution :Water BOILS at 373 K. EXPLANATION: This heat energy is called heat of VAPORISATION.

Discussion

1876.	At what temperature does water boil at atmospheric pressure?
Answer» 100K `100^(@)C` `-100^(@)C` `273K` ANSWER :B

Discussion

1877.	At what temperature does ice melt at atmospheric pressure?
Answer» `0^(@)C` `0K` `-0^(@)C` `100K` ANSWER :A

Discussion

1878.	At the end of the process of preparation of soap.common salt is added.Explain the role of common salt in the process.
Answer» Solution :application of Le Chatelier principle (ii) composition of soap TYPES (iii) of REACTIONS INVOLVED in the preparation of soap (iv) EFFECT of common salt on the final STEP of the reaction

Discussion

1879.	At room temperature, the force of attraction between the particles in solid matter is ………….than tha to of particle sof gaseous state of the same matter.
Answer» ANSWER :more

Discussion

1880.	At room temperature (30^(@)C) a student sets up an apparatus to determine the melting point of ice. He takes a beater half filled with ice and dips a mercury thermometer in it. The correct observation is……………………
Answer» mercury in the thermometer KEEPS on falling till it reads `-1^(@)C`. it remains CONSTAT thereafter. TEMPERATURE falls, reached `0^(@)C`, then it remains constnat even after the whole of the ice has melted. temperature falls, REACHES `0^(@)C` and remains constnat only as long as both ice and WATER present in it. temperature falls in the beginning but start rising as soon as the ice starts melting. Answer :C

Discussion

1881.	At melting point,
Answer» kinetic energy remains constant and potential energy increases kinetic energy increases and potential energy remains constant both potantial energy and kinetic energy INCREASE potential energy increases with a DECREASE in kinetic energy Solution :kineticenergy does notchange but potentialenergyincrease at MELTING POINT.

Discussion

1882.	At equilibrium properties, like, pressure, concentratio, density and colour remain constant.
Answer» ANSWER :TRUE

Discussion

1883.	At a fixed temperature, a solution in which no more solute can be added is called _____ solution.
Answer» ANSWER :SATURATED

Discussion

1884.	At 0^(@) and 760 mm Hg pressure, a gas occupies a volume of 100cm^(3). The Kelvin temperature of the gas is increased by one fifth, while the pressure is decreased by one fifth times. Calculate the final volume of the gas.
Answer» <P> Solution :`T_(1)=273orT""T_(2)=273+1/5xx273or6/5T` `P_(1)=760orP""P_(2)=760-1/5xx760or4/5P` `V_(1)=100""V_(2)=?` `(P_(1)V_(1))/T_(1)=(P_(2)V_(2))/T_(2),""(Pxx100)/T=(4PxxV_(2)xx5)/(5xx6T)` `(100xx6)/4=V_(2)` `V_(2)=150cm^(3)`

Discussion

1885.	Assertion (A) : In the preparation of oxygen from KClO_(3),MnO_(2) acts as a positive catalyst. Reasson (R ) : MnO_(2) decreases the activation energy of the reaction
Answer» Both A and R are CORRECT is the correct explanation of A. Both A and R are correct and R is not the correct explanation of A. A is correct and R is WRONG A is wrong and R is correct. Solution :Positive CATALYST DECREASES the ACTIVATION energy of the reaction. Hence, the rate of reaction increases.

Discussion

1886.	Asseration: Wrought iron is much more maleable than pig iron. Reason : Wrought iron is the purest form of iron.
Answer» Both A and R are true and R is the correct EXPLANATION for A. Both A and R are true but R is the correct explanation for A. A is true but R is false. A is false but R is true. Solution :Wrought iron is the PUREST form of iron and its carbon CONTENT is the least. Hence, it is highly malleable.

Discussion

1887.	Asseration : Diamond is agood condutor of heat. Reason : In diamond each carbon atom is bonded strongly to four other carbon atoms.
Answer» Both A and R are true and R is the correct EXPLANATION for A. Both A and R are true but R is the correct explanation for A. A is true but R is false. A is false but R is true. Solution :In diamond each carbon atom is bonded to four other carbon atoms and foroming RIGID three -dimensional structure. HENCE , it is a good conductor of HEAT.

Discussion

1888.	Aspirin is composed of 60% carbon, 4.5% Hydrogen 35.5% Oxygen by mass Aspirin is a mixture
Answer» Solution :Correct STATEMENT: The CONSTITUENTS of Aspirin are PRESENT in a fixed ratio by by MASS. So it is a compound.

Discussion

1889.	Aspirin is an …………………..
Answer» ANSWER :ANALGESICS

Discussion

1890.	As the presure of air decreases, the boiling point of a liquid
Answer» increases DECREASES remains fixed NONE of these ANSWER :B

Discussion

1891.	A_((s)) hArr B_((s))+C_((g))-"Heat" Arrange the conditions which are given below and applied on the above reaction in the increasing order of the yield : 1. low temperature and low pressure 2. high temperature and low pressure 3. continuous removal of the gas C and high temperature 4. low temperature and high pressure
Answer» 1 4 3 2 4 1 2 3 3 2 4 1 1 3 2 4 Solution :(i) low temperature and HIGH PRESSURE (II) low temperature and low pressure (iii) high temperature and low pressure (iv) continous removal of the gas C and high temperature

Discussion

1892.	Arun has prepared 0.01% (by mass) solution of sodium chloride in water. Which of the following correctly represents the composition of thesolutions?
Answer» 1.00 g of NaCl + 100 g of water 0.11 g of NaCl + 100 g water 0.01 g of NaCl + 99.99 g of water 0.10 g of NaCl + 99.90 g of water Solution :By definition 0.01% (by mass) solution means that 0.01 g of sodium CHLORIDE is dissolved in 0.99 g (by mass) of water. Therefore (c ) represents the correct COMPOSITION of the solution. This can be further VERIFIED as follows : Mass PERCENT = `("Mass of sodium chloride")/("Mass of solution")xx 100` `=((0.01g))/((0.99 + 0.01))xx 100 =0.01%`

Discussion

1893.	Arun has prepared 0.01% solution of sodium chloride in water. Which of the following correctly represents the composition of the solutions.
Answer» 1.00g of NACL + 100G of WATER 0.11g of Nacl + 100g of water 0.01g of Nacl + 99.99 of water 0.10g of Nacl + 99.90 of water Answer :C

Discussion

1894.	Arrange the statements in sequence for the calculation of weight of aluminium deposited during the electrolysis of molten aluminium chloride by passing c amperes of current for t minutes. (1) Find the product of current (c) and time (t). (2) Convert time in minutes to seconds. (3) Write reduction equation of the metal ion. (4) Conversion of charge into Faradays. (5) Relation between mass of metal and number of Faradays passed through
Answer» 2 1 4 3 5 1 2 3 4 5 4 2 1 5 3 2 1 4 5 3 Solution :(i) convert time in minutes to seconds (ii) Find the product of y current (c) and time (t). (iii) CONVERSION of CHARGE into Faradays. (iv) Write reduction equation of METAL ion. (v) relation between mass of metal and Faradays passed through

Discussion

1895.	Arrange the following substances in increasing order of forc es of attraction between the particles-water, sugar, oxygen.
Answer» Solution :The FORCES of attraction between the particles in a solid are the strongest, in liquids are less strong whereas in gases are the WEAKEST. Now, out of water, sugar and oxygen : (i)oxygen is a gas, so it has the weakest forces of attraction between its particles. (II)water is a LIQUID, so it has stronger forces of attraction between its particles (than oxygen). (iii) sugar is a solid, so it has the strongest forces of attraction between its particles. Thus, the increasing order of forces of attraction between the particles of water, sugar and oxygen will be : oxygen `lt`water `lt` sugar

Discussion

1896.	Arrange the following substances in increasing order to forces of attraction between the particles. Water, Sugar, Oxygen.
Answer» Solution :The FORCE of ATTRACTION will be highest in solids, FOLLOWED by liquids and the least in GASES. Oxygen is a gas, water is liquid and sugar is a crystalline solid. So the increasing order of forces at attraction is Oxygen

Discussion

1897.	Arrange the following substace in increasing order forces of attraction between the particles: Water, Sugar, Oxygen.
Answer» Solution :`UNDERSET(("Minimum force of ATTRACTION"))("Oxygen")lt"WATER"lt underset(("MAXIMUM force of attraction"))("Sugar")`

Discussion

1898.	Arrange the following steps which are carreid out in mu-ray experiment in the correct sequence: (i) Passage of mu- particles thorugh a slit. (ii) bombardment of mu-partilces with a gold foil (iii) deflection of mu-particles (iv) production of mu -particles
Answer» 4123 4132 1432 1423 Solution :(i) production of `alpha`-particles (II) production of a narrow beam of `alpha`-particles. (III) BOMBARDMENT of `alpha`-particles with gold foil (iv) DEFLECTION of `alpha`-particles.

Discussion

1899.	Arrange the following statements in chronological order :
Answer» 142 1342 4213 2413 Solution :(i) some element be grouped in sets of three elemets in the increasing order of their atomic weeghts in which the atomic weight of the middle element was FOUND to be the arithmetic mean of the atomicweightof the other TWO elements (ii) when the elements are arranged in the increasingorderof their ATOMICWEIGHT the eight element RESEMBLES the first in physical and chmeical porerties just as the eighth note on a musical scale resembles the first one (iii) The physical and chemical properites of elements are periodic functions of thei atomic weights (iv) The physical and chemical properites of elecments are periodic FUNCTION of their atomic number

Discussion

1900.	Arrange the following statements given by various scientists in chronological order :
Answer» 4 3 12 42 31 2431 4321 Solution :(i) ATOMS of the same elements are identical in all respects. (ii) Assumpation of thinly spread positively-charged mass. (iii) Calculation of the DIAMETERS of the nucleus and the atom (iv) Calculation of energy and RADIUS of orbit

Discussion

Explore topic-wise InterviewSolutions in .

Between 1000 litres water and 1000 litres CNG, CNG can be transported ealsily from one palce to another.

Batteries that are used mobile phone can be recharged. Likewise, can you recharge the batteries used in watches? Justify your answer.

Balance the unbalanced chemical equations.

Balance the following equations. N_2 + H_2 rarrNH_3

Balance the following equations. H_2 + O_2 rarrH_2O

Balance the following chemical equations. SO_2 + O_2 rarr SO_3

Balance the following chemical equations. Zn + HCl rarr ZnCl_2 + H_2

Balance the following chemical equations. Mg + O_2 rarr MgO

B and AI belong to the same group but the nature of oxides formed by them are different wheres Be AI form same type of oxide although they belong to different groups comment

aX to bY. The initial concentration of X is 0.6 M. After 10 min interval of time the concentration of X and Y are found to be 0.3 M and 0.2 M, respectively. Calculate the stoichiometric coefficients and rate of reaction with respect to X and Y.

(a)What do the following observations stand for? (i)2O (ii)3O_(2) (b)Which amongst the following has more number of atoms and how much? (i)11.5g of sodium (ii)15.0g of calcium

Avogadro constant represents ..................... particles.

Avogadaro's number represents the number of atoms in

Atoms whose nuclei contain different number of protons but same number of neutrons are called

Atoms of different elements have the same mass .

Atoms form the compound by combining in proper ratio of small integer number. The smallest part of this compound is called …...... .

Atomicweights of three elements in a doberenier traid are x , 81 and 127 .Find the missing atomic weight

Atomic number of the isotopes of an element are different

Atomic number and Atomic mass number

Atomic number

Atomic mass number

At what temperature in Kelvin scale does water boil? Explain what happens whenwe supply heat energy to water till it changes its state? What is the heat energy called?

At what temperature does water boil at atmospheric pressure?

At what temperature does ice melt at atmospheric pressure?

At the end of the process of preparation of soap.common salt is added.Explain the role of common salt in the process.

At room temperature, the force of attraction between the particles in solid matter is ………….than tha to of particle sof gaseous state of the same matter.

At room temperature (30^(@)C) a student sets up an apparatus to determine the melting point of ice. He takes a beater half filled with ice and dips a mercury thermometer in it. The correct observation is……………………

At melting point,

At equilibrium properties, like, pressure, concentratio, density and colour remain constant.

At a fixed temperature, a solution in which no more solute can be added is called _____ solution.

At 0^(@) and 760 mm Hg pressure, a gas occupies a volume of 100cm^(3). The Kelvin temperature of the gas is increased by one fifth, while the pressure is decreased by one fifth times. Calculate the final volume of the gas.

Assertion (A) : In the preparation of oxygen from KClO_(3),MnO_(2) acts as a positive catalyst. Reasson (R ) : MnO_(2) decreases the activation energy of the reaction

Asseration: Wrought iron is much more maleable than pig iron. Reason : Wrought iron is the purest form of iron.

Asseration : Diamond is agood condutor of heat. Reason : In diamond each carbon atom is bonded strongly to four other carbon atoms.

Aspirin is composed of 60% carbon, 4.5% Hydrogen 35.5% Oxygen by mass Aspirin is a mixture

Aspirin is an …………………..

As the presure of air decreases, the boiling point of a liquid

Arun has prepared 0.01% (by mass) solution of sodium chloride in water. Which of the following correctly represents the composition of thesolutions?

Arun has prepared 0.01% solution of sodium chloride in water. Which of the following correctly represents the composition of the solutions.

Arrange the following substances in increasing order of forc es of attraction between the particles-water, sugar, oxygen.

Arrange the following substances in increasing order to forces of attraction between the particles. Water, Sugar, Oxygen.

Arrange the following substace in increasing order forces of attraction between the particles: Water, Sugar, Oxygen.

Arrange the following steps which are carreid out in mu-ray experiment in the correct sequence: (i) Passage of mu- particles thorugh a slit. (ii) bombardment of mu-partilces with a gold foil (iii) deflection of mu-particles (iv) production of mu -particles

Arrange the following statements in chronological order :

Arrange the following statements given by various scientists in chronological order :