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151.

Write the balanced chemical equations for the following reactions : Calcium hydroxide + Carbon dioxide to Calcium carbonate + Water

Answer»

Solution :Balanced CHEMICAL EQUATIONS for the reactions are given as under :
`Ca(OH)_(2)+CO_(2)toCaCO_(3)+H_(2)O`
Discussion
152.

When lead nitrate is heated it breaks down into lead monoxide, nitrogen dioxide and oxygen 2Pb(NO_(3))_(2) to 2PbO + 4NO_(2) + O_(2) The reaction is an example of

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combination REACTION
decomposition reaction
double decomposition reaction
displacement reaction

Solution :`2Pb(NO_(3))_(2) to PBO + 4NO_(2) + O_(2)` IS an EXAMPLE of decomposition reaction.
Discussion
153.

Which of the following acid is used in fire extinguishers?

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HYDROCHLORIC ACID
SULPHURIC acid
nitric acid
oxalic acid

Solution :sulphuric acid
Discussion
154.

Third peroid of th periodic table contains the following number of elements.

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2
18
8
32

Solution :The third PERIOD consists of EIGHT ELEMENTS.
Na, MG, AI, Si, P,S, CI, AR
Discussion
155.

Which one of the following types of medicines is used for treating indigestion?

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ANTIBIOTIC
Analgesic
Antacid
Antiseptic

Solution :The indigestion is due to EXCESS of acid PRODUCED in the stomach. The medicine USED to NEUTRALISE it is called antacid.
Discussion
156.

When a blue litmus paper is dropped into a dilute solution of acetic acid, the colour of the litmus becomes

Answer»

green
yellow
orange
red

Answer :D
Discussion
157.

What is mean by binary solution?

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Solution :A solution must at LEAST be consisting of two COMPONENTS. Such solutions which are made of one solute and one solvent are CALLED BINARY solutions. E.g., On adding `CuSO_4` crystals to WATER.
Discussion
158.

Which carbohydrate substances, on decomposition form glucose ?

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Solution : CARBOHYDRATES such as RICE, potatoes and BREAD, etc. form glucose on their decomposition.
Discussion
159.

Why bubbling occurs when water is boiled?

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Solution :Solubility of a GASES in LIQUID decrease with increase in TEMPERATURE. GENERALLY, water contains dissolved OXYGEN. When water is boiled, the solubility of oxygen in water decreases, so oxygen escapes in the form of bubbles.
Discussion
160.

What type of bond will be formed if? (a) A combines with B? (b) A combines with E (c ) C combines with E (d) D combines with E

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Solution :TYPE of BOND
(a) A is METAL and B is non metal so the bond formed will be ionic:
A=2,8,1 B=2,7

(b) A is metal and E is non metal. So the bond formed is ionic.

(C ) C is metal and E is non metal so the bond formed is basic.
C=2,8,2 E=2,8,7

(d) D is a non metal and E is also a non metal , so the bond formed will be covalent.
D=2,8,5 E=2,8,7
Discussion
161.

Which of the following elements would lose an electron easily ?

Answer»

`MG`
`Na`
`K`
`Ca`

Solution :As we move down a group in the Periodic Table, the tendency to lose ELECTRON increases. Also when we move from left to right in a PERIOD, the tendency to lose electrons decreases. Combining these two results, K will lose the electron most easily.
Discussion
162.

Which one of the following has sour in taste?

Answer»

ETHANOL
ETHANOIC acid
Ethanal
ETHYNE

ANSWER :B
Discussion
163.

What is chlor-alkali process ? Give chemical reaction for process.

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Solution :When electricity is made to pass through an AQUEOUS solution of NACL, it decomposes to form NaOH. This process is called chlor-alkali processbecause of two products-chlor for Chlorine and alkali for SODIUM hydroxide.
`2NaCl(aq) + 2H_2O (l) to 2NaOH (aq) + Cl_2 (g) + H_2(g)` .
It is used in fertilizers, PVC, CFCS, Pesticides, paper making, artificial, fibres, soap and detergents.
Discussion
164.

What is soap?

Answer»

Solution :Soaps are sodium or potassium salts of some long chain carboxylic acids, called fatty acids. Soap REQUIRES TWO major raw materials: (i) FAT and (ii) alkali.
Discussion
165.

Which of the following statements in incorrect ?

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In oxidation , oxygen is added to a substanc.
In REDUCTION , hydrogen is added to a subtance
OXIDIZING AGENT is OXIDIZED .
Reducing agent is oxidized .

ANSWER :B
Discussion
166.

The substance used to remove moisture from ammonia is______________

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VANADIUM PENTOXIDE
SULPHURIC acid
Calcium oxide
Silicon dioxide

Answer :C
Discussion
167.

Which of the following statements is wrong?

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KCL is soluble in water
HCl conducts electricity in its aqueous SOLUTION
Acetic acid is soluble in water
The BOND formed between ALUMINUM and FLUORINE is covalent.

Answer :D
Discussion
168.

Which among the following statements is incorrect for magnesium metal ?

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It burns in oxygen with a dazzling white flame.
It reacts with cold WATER to FORM magnesium oxide and EVOLVES hydrogen gas.
It reacts with hot water to form magnesium hydroxide and evolves hydrogen gas.
It reacts with steam to form magnesium hydroxide and evolves hydrogen gas.

SOLUTION :Magnesium does not react with cold water.
Discussion
169.

What are Bio degradable and Non-biodegradabledetergents ?

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Solution :(i) BIO- degradabledetergent : Havestraighthydrocarbon chainswhich can be EASILY degraded by bacteria .
(ii) NON- BIODEGRADABLE : Have highly branchedhydrocarbon chainswhich cannot be degraded by bacteria.
Discussion
170.

What change in colour is observed when white silver chloride is left exposed to sunlight ? State the type of chemical reaction in this change.

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SOLUTION :SILVER CHLORIDE turns GREY. DECOMPOSITION reaction.
Discussion
171.

You are provided with magnesium ribbon and sulphur prowder. Explain with the help of an activity that metal oxides are basic and oxides of non-metals are acidic.

Answer»

Solution :Clean the SURFACE of the magnesium ribbon. Hold it in a pair of tongs and BURN in air. Collect the white ash formed in a china DISH. Transfer it in a test tuve and dissolved in water. Dip a red litmus paper strip in the solution. It willl change to blue showing that the metal oxides are of basic nature. The chemical equations involved are ,
`2Mg(s)+O_(2)(g)overset("heat")tounderset("Magnesium oxide")(2MgO(s))`
`MgO(s)+H_(2)O(aq)toMg(OH)_(2)(aq)`
Similarly, heat the sulphur powder on a spatual. When it starts burning, immediately dip it in a test tube CONTAINING water. Now dip a blue litmus paper in the SOLTION. It will immediately acquire red colour. This shows that oxides of non-metals are acidic in natue.
`S(s)+O_(2)(g)overset("heat")toSO_(2)(g)`
`SO_(2)(g)+H_(2)O(aq)toH_(2)SO_(3)(aq)`
Discussion
172.

What are alkynes?

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Solution : UNSATURATED HYDROCARBONS involving C to C triple bond `(C -= C)` are CALLED alkynes.
Discussion
173.

What are the types of molecules? Give example for each type?

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Solution :MOLECULES are of two types. (i) Homoatomic molecule. (ii) Heteroatomic molecule
(I0) Hhomoatomic molecule. The molecules which are MADE up of atoms of same ELEMENT are called Homoatomic molecules which are made up of atoms of same element are called Homoatomic molecule. e.g. `N_(2),O_(2),H_(2)`
(ii) Heteroatomic molecule. The molecules which are made up of atoms of same elements are called Heteroatomic molecule. e.g., `NH_(3), H_(2)O, CH_(4)`
Discussion
174.

When one mole each of CO and O_(2) are made to react at STP, the total number of moles at the end of the reactions is

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`1.5` MOLES
1 MOLE
4 mole
2 moles

Answer :A
Discussion
175.

What happens when (write balanced chemical equations only) Concentrated sulphuric acid is added to sodium chloride.

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SOLUTION :`2NaCl+H_(2)SO_(4)toNa_(2)SO_(4)+2HCL`
Discussion
176.

Which one of the following is an example of poly atomic molecule?

Answer»

Fluorine
GLUCOSE
Oxygen
Sodium

Solution :Glucose `(C_(6)H_(12)O_(6))`
Discussion
177.

What should be the position of Hydrogen in theModem Periodic Table? Why?

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Solution :In the MODERN PERIODIC Table, elements are arranged in the increasing order of their ATOMIC numbermm sio Hydrogen must be the FIRST element in the MODREN Periodic Table, because it has the last atomic number.
Discussion
178.

What is meant by activity or reactivity series?

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Solution : When DIFFERENT METALS are arranged in decreasing order of their ACTIVITIES or reactivities then it constitutes a series known as ACTIVITY or reactivity series.
Discussion
179.

Which of the following reactions will not occur? Give reasons. MgSO_4(aq)+Fe(s)to FeSO_4(aq)+Mg(s) (ii)MgSO_4(aq)+Cu(s) to CuSO_4(aq)+Mg(s) (iii)CuSO_4(aq)+Fe(s) to FeSO_4(aq)+Cu(s)

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SOLUTION :REACTION (i) will not occur because Fe is LESS reactive than MG. Reaction (ii) will not occur because Cu is less reactive than Mg.
Discussion
180.

What type of reaction is this : Na_(2)SO_(4)+BaCl_(2) to BaSO_(4)+2NaCl

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SOLUTION : It is a DOUBLE DISPLACEMENT REACTION.
Discussion
181.

What is rectified spirit ?

Answer»

Solution :Ethanol CONTAINING 5 PER CENT WATER is KNOWN as rectified spirit.
Discussion
182.

Write the steps involved in metallurgical process.

Answer»

Solution :A metallurgical PROCESS involves three main STEPS as follows:
(1)Concentration or Separation of the ORE: It is the process of removal of impuries from the ore.
(ii) Production of the METAL: It is the CONVERSION of the ore into metal. ,
(iii) Refining of the metal: It is the process of purification of the metal.
Discussion
183.

Which of the following is not a single displacement reaction ?

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`CuO+H_(2) to H_(2)O+Cu`
`Zn+CuSO_(4) to ZnSO_(4)+Cu`
`4NH_(3)+5O_(2) to 4NO+ 6H_(2)O`
`Zn+2HCl to ZnCl_(2)+H_(2)`

Solution :`4NH_(3)+5O_(2) to 4NO+ 6H_(2)O`
Discussion
184.

Which of the following do you expect to be formed when iron filings are heated with sulphur powder ?

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A homogeneous mixture
A HETEROGENEOUS mixture
A compound of iron and sulphur
A SUSPENSION of iron and sulphur

ANSWER :C
Discussion
185.

What is Molar volume of a gas?

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Solution :One mole of any gas occupies 22.4 LITRE (or) 22400 ML at S.T.P. This volume is CALLED as molar volume.
Discussion
186.

Which of the following elements is expected to show nonmetallic character ?

Answer»

As
Be
B
Br

Answer :D
Discussion
187.

Which of the given statements is (are) correct about the following reaction ? MgO(s) + H_(2)O(l) to Mg(OH)_(2)(s) + heat

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COMBINATION and ENDOTHERMIC
DISPLACEMENT and exothermic
Combination and exothermic
NONE of the above

Answer :C
Discussion
188.

Which of the following is the second member of the alkene homologous series ?

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Butyne
Propene
Ehtene
Pentene

ANSWER :B
Discussion
189.

What happens when dilute hydrochloric acid is added to iron fillings?

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Hydrogen gas and iron chloride are PRODUCED
Chlorine gas and iron hydroxide are produced
No reaction TAKES PLACE.
Iron SALT and water are produced.

Solution :Hydrogen gas and iron chloride are produced
Discussion
190.

What is seen to happen to the colour of the copper sulphate solution if platinum electrodes are used ? Explain this observation .

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Solution :The blue colour of COPPERSULPHATE fades because `CU^(2+)` ions of the solution migrate TOWARDS cathode and are REDUCED .
Discussion
191.

When CO_2 is passed through sodium hydroxide, it forms

Answer»

`NaHCO_3`
`Na_2CO_3`
both (a) and (B)
no REACTION

SOLUTION :both (a) and (b)
Discussion
192.

What happens when water soluble metals oxides are dissolved in water ? Give one example.

Answer»

Solution :When WATER soluble METAL oxides are dissolved in water we GET corresponding hydroxide.
`CaO+H_(2)OtoCa(OH)_(2)+H_(2)O`
Discussion
193.

Which of the following substances in water will not show acidic properties ? Sugar, alcohol, acetic acid, urea, nitric acid and carbon dioxide

Answer»

SOLUTION :Substances which give off `H^(+)` ions in solution show acidic properties.
Out of the substances given,sugar,ALCOHOL andurea do not produce `H^+` ions in solution. Hence, they will not show acidic properties.
Carbon dioxide in water give carbonic acid which is dissociated as
`CO_(2) + H_(2)O RARR H_(2)CO_(3) rarr 2H^(+) + CO_(3)^(2-)`
Hence, it shows acidic properties.
Discussion
194.

Which one of the following properties is not generally exhibited by ionic compounds ?

Answer»

SOLUBILITY in water
Electrical conductivity in solid state
High melting and boiling points
Electrical conductivity in molten state

SOLUTION : Ionic compounds conduct ELECTRICITY only in the molten state and not in solid state.
Discussion
195.

What is nuclear energy? What are the hazards of nuclear power generation?

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Solution :The energy produced during a nuclear REACTION such as nuclear fision or fusion is called nuclear energy, Nuclear wastes contains radioactive substances which emit harmful nuclear radiations. There is a HIGH risk of environment contamination. The radiations emitted from the nuclear waste penetrate deep inside the human or ANIMAL body where they can damage biological cells thereby initiate cancer or causes genetic diseases. Increased mortality of plants, soil INVERTEBRATES and mammals and reproductive losses in plants and animals have ALSO been observed.
Discussion
196.

What is the role of the seminal vesicles and the prostate gland?

Answer»

Solution :The secretion from SEMINAL vesicles and prostate glands lubricate the sperms and provide a fluid MEDIUM for EASY TRANSPORT the secretions also provide nutrient in the from of fructose calcium and some ENZYMES.
Discussion
197.

What are the advantagesof detergentsover soaps ?

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Solution :Detergents are betterthan soapsbecausethey ,
(i) can be usedin both hard and softwater and can clean more effectively in hard waterthan soap .
(ii) can also be used in saline and acidic water .
(III) do not leaveany soap SCUM on the tub or clothes .
(iv) dissolvefreely even in cool waterand rinsefrrely in hard water .
(v) can be used for WASHING woollen GARMENTS , where as soap cannotbe used .
(vi) have a linearhydrocarbon CHAIN, which is biodegradable .
(vii) are activeemulsifiersof motorgrease .
(viii) do an effectiveand safecleansing , keepingeven synthetic fibricsbrighterand whiter .
Discussion
198.

Which of the following is not an acidic salt?

Answer»

`CuSO_4`
`Na_2 CO_3`
`ZnSO_4`
`NH_4 NO_3`

Solution :`Na_2 CO_3` is a SALT of a story base NAOH and weak ACID, `H_2 CO_3` and hence, BASIC salt.
Discussion
199.

Which element was not known when Mendeleev framed the periodic table?

Answer»

GERMANIUM
SILICON
URANIUM
Sulphur

Answer :A
Discussion
200.

Zincblende is purified by …………….. .

Answer»

HYDRAULIC method
MAGNETIC Separation method
Froth floatation method

ANSWER :C
Discussion