8881 + Interview Questions in Chemistry in Class 10 Page 149 InterviewSolution

7401.	At present, naturally occurring elements are 98.
Answer» ANSWER :TRUE

Discussion

7402.	At NTP, the mass of 1 litre of gas is 3 g. Molecular mass of the gas is _____________
Answer» ANSWER :67.2

Discussion

7403.	At theequilibriumof a reversiblereaction , theconcentrationof thereactantsand theproducts willbe equal .
Answer» ANSWER :TRUE

Discussion

7404.	At a certain temperature, K_(w) was found to be 1 xx 10^(-10) mol^(2)//L^(2). At this temperature, a solution is taken and red litmus is added to this solution. The solution turned to blue. pH range of the solution could be
Answer» between 5 and 7 between 7 and 10 less than 5 both 1 and 2 Answer :D

Discussion

7405.	Assuming that 2NO + O_(2) to 2NO_(2) is a single-step reaction, what will be the rate of reaction when the volume of the reaction vessel is reduced of 1//4^(th) of the initial value ? The original rate of reaction is 64 mol/L/s.
Answer» Solution :`2NO + O_(2)to 2NO_(2)` The rate of the reactioin r`=k[NO]^(2)[O_(2)]`, as it is a single-step reaction. When the volume of the reaction vessel is reduced to `1//4^(TH)` of the initial volume, the concentration of each reactant is increased by four-times. Since the reaction is a second order with respect to NO and first order with respect to `O_(2)` , the rate of reaction INCREASES by 16-times for NO and 4-times for `O_(2)`. On the WHOLE , the rate of reaction increases by 64-times . The ORIGINAL rate of reaction is 64 mol/L/s and the new rate of reaction is 64-times more than this. `r_(2)=64xx64=4096=4.096xx10^(3)` mol/L/s.

Discussion

7406.	Assertion(A):When lead nitrate is heated the gas released has red orange colour and it is lead oxide. Reason (R ):Lead nitrate on heating undergoes combination reaction.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :B

Discussion

7407.	Assertion(A)When glucose is kept on our tongue ,a cooling effect is felt. Reason(R ):It is an endothermic reaction in which heat is absorbed .
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :A

Discussion

7408.	Assertion(A):Powdered calcium carbonate reacts more quickly with hydrochloric acid than marble chips. Reason(R ):Powdered calcium carbonate offers large offers large surface area than marble chips .Because greater the surface area,the greater is the rate of the reaction.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :B

Discussion

7409.	Assertion(A):Iron is more reactive than copper. Reason(R ):Iron is displaced from than sulphate by copper.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :B

Discussion

7410.	Assertion(A):Combination reaction are exothemic in nature. Reason (R ):During the formation of new bonds,releases a huge amount of enerfy in the form of heat.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :A

Discussion

7411.	Assertion(A):All combustion reactions are exothermic reactions. Reason (R ):During combustion reaction,heat energy is liberated.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :A

Discussion

7412.	Assertion(A): When copper carbonate is heated strongly ,the green colour is changed into black colour Reason(R ):The colour change is due to the decomposition of copper carbonate into copper oxide.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :A

Discussion

7413.	Assertion(A): During the reaction of calcium carbonate with dilute with dilute hydrochloric acid,brisk effervscence takes place. Reason (R ):Brisk effervescence is due to the evolution of carbondioxide gas
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :B

Discussion

7414.	Assertion(A): Copper displaces zinc (or)lead from salt solution. Reason (R ):Copper is more reactivee than zinc and lead.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :D

Discussion

7415.	Assertion : Thereare more than 5 milion hydrocarbons. Reason : Carbonhas unique propretiessuch as catenation , tetra valency and multiplebonding .
Answer» Both ASSERTION and REASON are trueand Reason is correct EXPLANATION of Assertion . Both Assertion and Reason are true but Reasonis not the correct explanation of Assertion . Assertion is true but Reasonis FALSE . Assertion is falsebut Reason is true . ANSWER :A

Discussion

7416.	Assertion : therelativemolecularmassofchlorineis 35.5 a.m.u Reason :the naturalabundanceofchlorineisotopesare notequal .
Answer» A andR arecorrect. Rexplainsthe A . A is correct, Ris WRONG. A ISWRONG, Riscorrect A and Rare correct, Rdoesn'texplains A . Solution :ATOMICMASS ofchlorinein35.5 amu. Molecularmass wouldbe twicethe atomicmass , thatis 71amu.

Discussion

7417.	Assertion : The Relative Molecular Mass of Chlorine is 35.5 a.m.u. Reason : The natural abundance of Chlorine isotopes are not equal.
Answer» A and R CORRECT, R EXPLAINS the A. A is correct, R is WRONG. A is wrong, R is correct. A and R are correct, R doesn't explains A. Solution :A and R are correct, R explains the A.

Discussion

7418.	Assertion : The nature of bond is HF molecule is ionic . Reason : The electronegativity difference between H and F is 1.9.
Answer» A and R are correct , R explain the A . A is correct, R is correct A is wrongR is correct . A and R are correct , R doesn't explain A . Solution :Bond between H and F in HF consideredpolar COVALENT .

Discussion

7419.	Assertion : The nature of bond in HF molecule is ionic Reason : The electronegativitiy difference between H and F is 1.9
Answer» A and R are CORRECT, R EXPLAINS the A. A is correct, R is WRONG A is wrong, R is correct A and R are correct, R doesn't explains A. SOLUTION :N/A

Discussion

7420.	Assertion : The molecular weight of oxygen is 32 amu. Reason : The atomic weight of oxygen is 16 amu
Answer» If both ASSERTION & Reason are true and the reason is the correctexplanation of the assertion. If both Assertion & Reason are true but the reason is not the correctexplanation of the assertion. If Assertion is true statement but Reason is FALSE. If both Assertion and Reason are false statements. ANSWER :A

Discussion

7421.	Assertion: oneamuof anatomequalto exactly(1)/(12^(th))of massofC-12atom . Reason:Carbon- 12isotopeswasselected asstandard.
Answer» BothassertionandReasonaretrueandReasonis correctexplanationof ASSERTION bothassertionand Reasonis notthe correctexplanationof assertion Assertionis falsebutreasonis true Assertionis truebut reason is FALSE ANSWER :A

Discussion

7422.	Assertion : Number of atoms of He in 60 u of He is 15. Reason :Atomic weight of He is 4 u.
Answer» If both ASSERTION & Reason are TRUE and the reason is the CORRECTEXPLANATION of the assertion. If both Assertion & Reason are true but the reason is not the correctexplanation of the assertion. If Assertion is true statement but Reason is false. If both Assertion and Reason are false statements. ANSWER :A

Discussion

7423.	Assertion : Noblegaseshavezero electron affinity . Reason : Noblegaseshave completely filled electronic configuration .
Answer» Both Assertionand REASON are ture and Reason is correct explanation of ASSERTION. Both Assertionand Reasonare true but Reason is OT the correct explanation of Assertion. Assertion is true but Reason is FALSE. Assertion is false but reason is true. ANSWER :A

Discussion

7424.	Assertion : No of moles of H2 in 0.224 L of hydrogen is 0.01 mole. Reason : 22.4 L of H_(2)at STP contain 6.023 xx 10^(23) moles.
Answer» If both ASSERTION & Reason are true and the reason is the CORRECTEXPLANATION of the assertion. If both Assertion & Reason are true but the reason is not the correctexplanation of the assertion. If Assertion is true STATEMENT but Reason is false. If both Assertion and Reason are false STATEMENTS. Answer :C

Discussion

7425.	Assertion : NA uncleanedcoppervessel is covered with greenish layer. Reason : Copper is not attacked by alkali.
Answer» A and R are CORRECT , R EXPLAIN the A . A is correct, R is correct A is WRONGR is correct . A and R are correct , R doesn't explain A . ANSWER :D

Discussion

7426.	Assertion: Molecularweightof SO_(2)is doubletothat of O_(2)Reason : one moleof SO_(2)containsdoublethenumberof molecule presentin onemoleof O_(2)
Answer» BothassertionandReasonaretrueandReasonis correctexplanationof ASSERTION bothassertionand REASONIS NOTTHE correctexplanationof assertion Assertionis falsebutreasonis true Assertionis truebut reason is false ANSWER :D

Discussion

7427.	Assertion : Magnesium is used to protect steel from rusting Reason : Magnesium is more reactive than iron
Answer» A and R are CORRECT, R EXPLAINS the A. A is correct, R is WRONG A is wrong, R is correct A and R are correct, R doesn't explains A. SOLUTION :N/A

Discussion

7428.	Assertion : Magnesium is used to protect steel from rusting . Reason : Magnesiumis more reactivethan iron .
Answer» A and R are CORRECT , R EXPLAIN the A . A is correct, R is correct A is WRONGR is correct . A and R are correct , R doesn't explain A . ANSWER :A

Discussion

7429.	Assertion : Ionizationenergy increase does the group. Reason :Atomic size increasesdown the group.
Answer» Both Assertionand Reason are ture and Reason is correct EXPLANATION of ASSERTION. Both Assertionand Reasonare true but Reason is OT the correct explanation of Assertion. Assertion is true but Reason is false. Assertion is false but reason is true. ANSWER :D

Discussion

7430.	Assertion :Ionic radius of Na^+is smaller than Na Reason: Effective nuclear charge of Na^+is higher than Na
Answer» If both Assertion & REASON are TRUE and the reason is the CORRECTEXPLANATION of the assertion. If both Assertion & Reason are true but the reason is not the correctexplanation of the assertion. If Assertion is true statement but Reason is FALSE. If both Assertion and Reason are false statements. Answer :A

Discussion

7431.	Assertion : In thermite welding , aluminium powder and Fe_2O_3 are used Reason : Aluminium powder is a strong reducing agent .
Answer» Both Assertionand REASON are TURE and Reason is correct EXPLANATION of Assertion. Both Assertionand Reasonare true but Reason is OT the correct explanation of Assertion. Assertion is true but Reason is FALSE. Assertion is false but reason is true. Answer :A

Discussion

7432.	Assertion : I.E_1 gt I.E_2 gt I.E_3.Reason : Increase innuclear charge shows strong force of attraction.
Answer» Both Assertionand REASON are ture and Reason is CORRECT EXPLANATION of Assertion. Both Assertionand Reasonare true but Reason is ot the correct explanation of Assertion. Assertion is true but Reason is false. Assertion is false but reason is true. Answer :A

Discussion

7433.	Assertion: Homoatomicmoleculesare madeofatomsof the sameelements reason: H_(2)Oconsistsofhydrogen andoxygen
Answer» AssertionisrightReasonis WRONG Assertionis wrongReasonis RIGHT ReasonexplainAssertion Reasondoes notexplainassertion Answer :D

Discussion

7434.	Assertion : First ionisation enthalpy of Galium is higher than aluminium. Reason : Weak sheliding effect of 3d subshell is Galium.
Answer» If both ASSERTION & Reason are TRUE and the reason is the correctexplanation of the assertion. If both Assertion & Reason are true but the reason is not the correctexplanation of the assertion. If Assertion is true statement but Reason is FALSE. If both Assertion and Reason are false statements. Answer :A

Discussion

7435.	Assertion : First ionisation enthalpy of N is higher than O. Reason : Extra stability of fully filled up 2p subshell of N atom
Answer» If both ASSERTION & REASON are true and the reason is the CORRECTEXPLANATION of the assertion. If both Assertion & Reason are true but the reason is not the correctexplanation of the assertion. If Assertion is true STATEMENT but Reason is false. If both Assertion and Reason are false statements. Answer :A

Discussion

7436.	Assertion : Electron gain enthalpy of Cl is more negative than F atom. Reason : F is more electronegative than Cl atom.
Answer» If both ASSERTION & REASON are TRUE and the reason is the correctexplanation of the assertion. If both Assertion & Reason are true but the reason is not the correctexplanation of the assertion. If Assertion is true statement but Reason is false. If both Assertion and Reason are false statements. Answer :B

Discussion

7437.	Assertion: Detergents are more effective cleansing agents than soaps in hard water. Reason: Calcium and magnesium salts of detergents are water soluble.
Answer» A and R are CORRECT, R EXPLAINS the A. A is correct, R is WRONG. A is wrong, R is correct. A and R are correct, R doesn't explains A. Answer :ii

Discussion

7438.	Assertion : Detergents are more effective cleansingagentsthan soaps in hard water . Reason : Calcium and magnesiumsaltsof detergentsare water soluble .
Answer» AAND R are CORRECT , R explain the A . A is correct, R is WRONG . A is wrong, R is correct A and Rare correct , R doesn't explain A . ANSWER :A

Discussion

7439.	Assertion : Copper pyrite is concentrated by froth flotation. Reason : Copper pyriteis an oxide ore.
Answer» Both Assertionand Reason are ture and Reason is CORRECT explanation of Assertion. Both Assertionand Reasonare TRUE but Reason is ot the correct explanation of Assertion. Assertion is true but Reason is FALSE. Assertion is false but reason is true. ANSWER :C

Discussion

7440.	Assertion : Copperis extensively used in manufactureof electric cables Reason : Copper is a very poor conductor of heat and electricity.
Answer» Both Assertionand Reason are TURE and Reason is CORRECT explanation of ASSERTION. Both Assertionand Reasonare true but Reason is ot the correct explanation of Assertion. Assertion is true but Reason is FALSE. Assertion is false but reason is true. Answer :C

Discussion

7441.	Assertion (A):When glucose is kept on our tongue,a cooling effect is felt. Reason (R ):It is an endothermic reaction in which heat is absorbed.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :A

Discussion

7442.	Assertion: Atomicityofsulphuris 8 Reason :1 moleof anelementcontains6.023xx 10 ^(23)atoms .
Answer» BothassertionandReasonaretrueandReasonis correctexplanationof ASSERTION bothassertionand REASON are true and reasonis notthe correctexplanationof assertion Assertionis falsebutreasonis true Assertionis truebut reason is FALSE ANSWER :B

Discussion

7443.	Assertion:Atomicityof nitrogen is 2 Reason : Atpmicity =("Molecularmass ")/( "Atomicmass ")
Answer» BothassertionandReasonaretrueandReasonis correctexplanationof ASSERTION bothassertionand REASONIS notthe correctexplanationof assertion Assertionis falsebutreasonis TRUE Assertionis truebut reason is false Solution :Atomicmassesof mostof THEELEMENTS are notwholenumbers.

Discussion

7444.	Assertion: atomicmassesof elements arewholenumbers . Reason: atoms of thesameelement existasisotopes .
Answer» BothassertionandReasonaretrueandReasonis correctexplanationof assertion bothassertionand Reasonis NOTTHE correctexplanationof assertion Assertionis falsebutreasonis TRUE Assertionis truebut reason is FALSE Answer :C

Discussion

7445.	Assertion : Atomic mass of Na is 23. Reason : An atom of sodium is 23 times heavier than 1/12th mass ofC-12 isotope.
Answer» If both Assertion & REASON are true and the reason is the correctexplanation of the assertion. If both Assertion & Reason are true but the reason is not the correctexplanation of the assertion. If Assertion is true STATEMENT but Reason is FALSE. If both Assertion and Reason are false statements. Answer :A

Discussion

7446.	Assertion : Atomic mass of aluminium is 27 Reason : An atom of aluminium is 27 times heavier than 1//12^("th") of the mass of the C-12 atom.
Answer» A and R CORRECT, R EXPLAINS the A. A is correct, R is WRONG. A is wrong, R is correct. A and R are correct, R doesn't explains A. Solution :A and R are correct, R explains the A.

Discussion

7447.	Assertion (A):The reaction of calcium oxide with is an exothermic reaction. Reason(R ):The reaction is accompanied by a hissing sound and formation of bubbles leading to the absorption of considerable amount of heat.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :C

Discussion

7448.	Assertion (A):The lustrous white colour of the silver anklet slowly changes into slightly anklet slowly changes into slightly back colour. Reason(R ):Silver anklet reacts with H_(2)S in the air to form Ag_(2)S (silver sulphide) which in black In colour.
Answer» Both (A)and ( R) CORRECT (A) is correct but (R ) is WRONG Both (A) and (R ) are wrong (A) is wrong but (R ) is correct Answer :A

Discussion

7449.	Assertion: atomicmassof aluminium is 27 Reason: anatomof aluminiumis27timesheavierthan(1)/(12 ^(th)) of themassof theC- 12atom .
Answer» A ANDR arecorrect. Rexplainsthe A . A is CORRECT, Ris wrong. A iswrong, Riscorrect A and RARE correct, Rdoesn'texplains A . ANSWER :D

Discussion

7450.	Assertion : An uncleaned copper vessel is covered with greenish layer. Reason : Copper is not attacked by alkali
Answer» A and R are CORRECT, R EXPLAINS the A. A is correct, R is WRONG A is wrong, R is correct A and R are correct, R doesn't explains A. SOLUTION :N/A

Discussion

Explore topic-wise InterviewSolutions in .

At present, naturally occurring elements are 98.

At NTP, the mass of 1 litre of gas is 3 g. Molecular mass of the gas is _____________

At theequilibriumof a reversiblereaction , theconcentrationof thereactantsand theproducts willbe equal .

At a certain temperature, K_(w) was found to be 1 xx 10^(-10) mol^(2)//L^(2). At this temperature, a solution is taken and red litmus is added to this solution. The solution turned to blue. pH range of the solution could be

Assuming that 2NO + O_(2) to 2NO_(2) is a single-step reaction, what will be the rate of reaction when the volume of the reaction vessel is reduced of 1//4^(th) of the initial value ? The original rate of reaction is 64 mol/L/s.

Assertion(A):When lead nitrate is heated the gas released has red orange colour and it is lead oxide. Reason (R ):Lead nitrate on heating undergoes combination reaction.

Assertion(A)When glucose is kept on our tongue ,a cooling effect is felt. Reason(R ):It is an endothermic reaction in which heat is absorbed .

Assertion(A):Powdered calcium carbonate reacts more quickly with hydrochloric acid than marble chips. Reason(R ):Powdered calcium carbonate offers large offers large surface area than marble chips .Because greater the surface area,the greater is the rate of the reaction.

Assertion(A):Iron is more reactive than copper. Reason(R ):Iron is displaced from than sulphate by copper.

Assertion(A):Combination reaction are exothemic in nature. Reason (R ):During the formation of new bonds,releases a huge amount of enerfy in the form of heat.

Assertion(A):All combustion reactions are exothermic reactions. Reason (R ):During combustion reaction,heat energy is liberated.

Assertion(A): When copper carbonate is heated strongly ,the green colour is changed into black colour Reason(R ):The colour change is due to the decomposition of copper carbonate into copper oxide.

Assertion(A): During the reaction of calcium carbonate with dilute with dilute hydrochloric acid,brisk effervscence takes place. Reason (R ):Brisk effervescence is due to the evolution of carbondioxide gas

Assertion(A): Copper displaces zinc (or)lead from salt solution. Reason (R ):Copper is more reactivee than zinc and lead.

Assertion : Thereare more than 5 milion hydrocarbons. Reason : Carbonhas unique propretiessuch as catenation , tetra valency and multiplebonding .

Assertion : therelativemolecularmassofchlorineis 35.5 a.m.u Reason :the naturalabundanceofchlorineisotopesare notequal .

Assertion : The Relative Molecular Mass of Chlorine is 35.5 a.m.u. Reason : The natural abundance of Chlorine isotopes are not equal.

Assertion : The nature of bond is HF molecule is ionic . Reason : The electronegativity difference between H and F is 1.9.

Assertion : The nature of bond in HF molecule is ionic Reason : The electronegativitiy difference between H and F is 1.9

Assertion : The molecular weight of oxygen is 32 amu. Reason : The atomic weight of oxygen is 16 amu

Assertion: oneamuof anatomequalto exactly(1)/(12^(th))of massofC-12atom . Reason:Carbon- 12isotopeswasselected asstandard.

Assertion : Number of atoms of He in 60 u of He is 15. Reason :Atomic weight of He is 4 u.

Assertion : Noblegaseshavezero electron affinity . Reason : Noblegaseshave completely filled electronic configuration .

Assertion : No of moles of H2 in 0.224 L of hydrogen is 0.01 mole. Reason : 22.4 L of H_(2)at STP contain 6.023 xx 10^(23) moles.

Assertion : NA uncleanedcoppervessel is covered with greenish layer. Reason : Copper is not attacked by alkali.

Assertion: Molecularweightof SO_(2)is doubletothat of O_(2)Reason : one moleof SO_(2)containsdoublethenumberof molecule presentin onemoleof O_(2)

Assertion : Magnesium is used to protect steel from rusting Reason : Magnesium is more reactive than iron

Assertion : Magnesium is used to protect steel from rusting . Reason : Magnesiumis more reactivethan iron .

Assertion : Ionizationenergy increase does the group. Reason :Atomic size increasesdown the group.

Assertion :Ionic radius of Na^+is smaller than Na Reason: Effective nuclear charge of Na^+is higher than Na

Assertion : In thermite welding , aluminium powder and Fe_2O_3 are used Reason : Aluminium powder is a strong reducing agent .

Assertion : I.E_1 gt I.E_2 gt I.E_3.Reason : Increase innuclear charge shows strong force of attraction.

Assertion: Homoatomicmoleculesare madeofatomsof the sameelements reason: H_(2)Oconsistsofhydrogen andoxygen

Assertion : First ionisation enthalpy of Galium is higher than aluminium. Reason : Weak sheliding effect of 3d subshell is Galium.

Assertion : First ionisation enthalpy of N is higher than O. Reason : Extra stability of fully filled up 2p subshell of N atom

Assertion : Electron gain enthalpy of Cl is more negative than F atom. Reason : F is more electronegative than Cl atom.

Assertion: Detergents are more effective cleansing agents than soaps in hard water. Reason: Calcium and magnesium salts of detergents are water soluble.

Assertion : Detergents are more effective cleansingagentsthan soaps in hard water . Reason : Calcium and magnesiumsaltsof detergentsare water soluble .

Assertion : Copper pyrite is concentrated by froth flotation. Reason : Copper pyriteis an oxide ore.

Assertion : Copperis extensively used in manufactureof electric cables Reason : Copper is a very poor conductor of heat and electricity.

Assertion (A):When glucose is kept on our tongue,a cooling effect is felt. Reason (R ):It is an endothermic reaction in which heat is absorbed.

Assertion: Atomicityofsulphuris 8 Reason :1 moleof anelementcontains6.023xx 10 ^(23)atoms .

Assertion:Atomicityof nitrogen is 2 Reason : Atpmicity =("Molecularmass ")/( "Atomicmass ")

Assertion: atomicmassesof elements arewholenumbers . Reason: atoms of thesameelement existasisotopes .

Assertion : Atomic mass of Na is 23. Reason : An atom of sodium is 23 times heavier than 1/12th mass ofC-12 isotope.

Assertion : Atomic mass of aluminium is 27 Reason : An atom of aluminium is 27 times heavier than 1//12^("th") of the mass of the C-12 atom.

Assertion (A):The reaction of calcium oxide with is an exothermic reaction. Reason(R ):The reaction is accompanied by a hissing sound and formation of bubbles leading to the absorption of considerable amount of heat.

Assertion (A):The lustrous white colour of the silver anklet slowly changes into slightly anklet slowly changes into slightly back colour. Reason(R ):Silver anklet reacts with H_(2)S in the air to form Ag_(2)S (silver sulphide) which in black In colour.

Assertion: atomicmassof aluminium is 27 Reason: anatomof aluminiumis27timesheavierthan(1)/(12 ^(th)) of themassof theC- 12atom .

Assertion : An uncleaned copper vessel is covered with greenish layer. Reason : Copper is not attacked by alkali