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2151.

The various physical properties of a substance may include

Answer»

COLOUR, odour and taste only
hardness, solubility and density only
melting POINT and boiling point only
all of these

Solution :all of these
Discussion
2152.

Which gas is produced when dilute hydrochloric acid is added to a reactive metal ? Write the chemical reaction when iron reacts with dilute H_2SO_4

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SOLUTION : When a reactive METAL reacts with dilute hydrochloric acid, it FORMS HYDROGEN gas. The reactive metal displaces the hydrogen from acid releasing hydrogen gas.
`Fe(s)+ underset("dilute")(H_2SO_4)(aq) to FeSO_4(aq) + H_2(g)`
Discussion
2153.

What happens when sodium metal is dropped in water?

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Solution :It FORMS washing SODA. It gets hydrated - `Na_(2)CO_(3).10H_(2)O`.
Discussion
2154.

Write the molecular formula of the following compounds and draw their electron-dot structures: (i) Ethane(ii) Ethene (iii) Ethyne

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Solution :(i) ETHANE: The molecular formula is `C_(2)H_(6)`.
Electron-dot STRUCTURE:
(ii) Ethene: The molecular formula is `C_(2)H_(4)`.
Electron-dot structure:

(III) Ethyne: The molecular formula is `C_(2)H_(2)`.
Electron-dot structure:
Discussion
2155.

(i) Which of the following statements is wrong about alkanes ? (A) They are all saturated hydrocarbon. (B) They can undergo addition as well as substitution reaction. (C) They are almost non polar in nature. (D) On complete combustion give out carbon dioxide and water.

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They are all SATURATED hydrocarbon.
They can undergo ADDITION as well as substitution reaction.
They are almost non-polar in NATURE.
On complete combustion give out carbon dioxide and water.

Answer :B
Discussion
2156.

Translate the following statements into chemical equations and then balance them. Hydrogen gas combines with nitrogen to form ammonia .

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SOLUTION :`3H_2(G)+N_2(g)to2NH_3(g)`
Discussion
2157.

Write the balanced chemical equation for the following chemical reactions : Barium chloride + Aluminium sulphate to barium sulphate and aluminium chloride.

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SOLUTION :`3BaCl_(2)+Al_(2)(SO_(4))_(3)to3BaSO_(4)+2AlCl_(3)`
Discussion
2158.

Write the chemical equation for combustion of ethanol.

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Solution :`CH_(3)CH_(2)OH + 3O_(2) RARR 2CO_(2) + 3H_(2)O`.
Discussion
2159.

Which element is the most electronegative?

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A(2,2)
B(2,3)
C(2,4)
D(2,5)

Solution :All FOUR ELEMENTS belongs to the same PERIOD. Across the period, atomic SIZE decreases and electronegativity increases.
Discussion
2160.

The solution in which water acts as a solvent, is called .................. and the solution in which Benzene acts as a solvent is called ........

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SOLUTION :AQUEOUS solution, Non-aqueous solution
Discussion
2161.

Write the balanced chemical equation and identify the type of reaction in each case. Lead acetate solution is treated with dilute hydrochloric acid to form lead chloride and acetic acid solution.

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Solution :`(CH_(3)COO)_(2)PB(AQ.)to2HCl(aq.)toPbCl_(2)(aq.)+2CH_(3)COOH`.
Discussion
2162.

Write the molecular formula of the third member of the homologous series of carbon compounds with general formula C_(n)H_(2n+1)OH.

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SOLUTION :`C_(3)H_(2xx3+1)OHi.e.,C_(3)H_(7)OH`
Discussion
2163.

Which of the following is a noncoventional source of energy?

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Coal
Petrol
Diesel
Wind ENERGY

ANSWER :D
Discussion
2164.

What is called an exothermic chemical reaction ? Give examples.

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Solution :CHEMICAL reaction in which heat is released during the formation of product is called an exothermic reaction.
Examples :
(1) Burning of natural gas :
`CH_(4)(G) + 2O_(2)(g) to CO_(2)(g) + 2H_(2)O(g)`
(2)Burning of coal :
`C(s) + O_(2)(g)toCO_(2)(g) + "Heat"`
(3) Formation of compost manure by decomposition of vegetable matter is also an example of an exothermic reaction.
Discussion
2165.

Which of the following is the outermost shell for clements of period 2?

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K SHELL
L shell
M shell
N shell

Answer :B
Discussion
2166.

Write the name of the following compounds : (i) H-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-overset(O)overset(||)(C)-OH (ii) H-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-overset(H)overset(|)(C)-=C-H (iii) H-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-V-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-overset(H)overset(|)C=O (iv) H-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-underset(H)underset(|)overset(H)overset(|)-OH

Answer»


Answer :(i) Pentanoic acid, (II) Butyne
(III) Heptanal, (IV) PENTANOL
Discussion
2167.

What is meant by a group in the Modern Periodic Table? How do the following change on moving from top to bottom in a group? i] Number of valence electrons ii] Number of occupied shells iii] Size of atoms iv] Metallic character of elements v] Effective nuclear charge experienced by valence electrons

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Solution :VERTICAL columns of the periodic table are known as groups.
(i) The number of valence ELECTRONS remains constant when we move down the group.
(II) The number of occupied shells increases down the group.
(iii) The size of atom increases down the group.
(iv) The metallic CHARACTER of elements increases down the group.
(V) The effective nuclear charge decreases down the group.
Discussion
2168.

When carbon dioxide is passed through lime water, it turns milky. Why?

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Solution : LIME WATER (CALCIUM hydroxide) combines with Carbondioxide to FORM a suspension of Calcium carbonate, which MAKES lime water milky.
Discussion
2169.

Which is widely used scale to determine the eletronegativity ?

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Pauling scale
MOSELEY scale
MENDELEEV scale
none of these

Answer :A
Discussion
2170.

There are seven elemetrons in the outermost shell of the elements, such elements belong of the family of __________ .

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SOLUTION :HALOGENS
Discussion
2171.

Which among the following statements is false ?

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EVERY protonic ACID has its conjugate acid
Pair of Bronsted acid and base that differ by a proton is conjugate acid-base pair
A SUBSTANCE that accepts an electron pair to FORM co-ordinate covalent bond is an acid
Arrhenius theory is confined to AQUEOUS solution

Solution :Every protonic acid has a conjugate base
Discussion
2172.

Which gas is usually liberated when an acid reacts with a metal?

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SOLUTION :HYDROGEN GAS
Discussion
2173.

Under what conditions, gases deviate to a large extent from ideal behaviour? Justify with respect to kinetic molecular theory.

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SOLUTION :(i) requisite for deviation from ideal behaviour
(ii) consequences of high pressure and low temperature
(iii) comparison of actual volume occupied by realgases and ideal gases
(IV) comparison of intermolecular FORCES of attraction in the above said CONDITION
Discussion
2174.

When zinc powder is heated with sodium hydroxide solution , the substances formed are

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ZINC hydroxide and hydrogen
zinc OXIDE and oxygen
sodiumzincate and hydrogen
zinc hydroxide and WATER

Answer :C
Discussion
2175.

The structural formula of an ester is : Write the structural formula of the acid and the alcohol from which it might be prepared. Name the process of formation of ester.

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SOLUTION :`CH_(3)UNDERSET"ACID"(COOH) +underset"Alcohol"(C_(4)H_(9)OH)rightarrowCH_(3)underset"Ester"(COOC_(4)H_(9)) + H_(2)O`

PROCESS Esterification.
Discussion
2176.

Which one of the following does not increase while moving down the group of the periodic table ?

Answer»

ATOMIC RADIUS
Metallic character
Valence electrons
BASICITY of oxides

Answer :A::C
Discussion
2177.

The shiny finish to the walls is because of

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calcium oxide.
calcium hydroxide
calcium CARBONATE.
calcium phosphate.

Solution :`CA(OH)_(2)+CO_(2)tounderset("Calcium Carbonate")(CaCO_(3))+H_(2)O`
Discussion
2178.

Which of the following pairs make pairs make a homogeneous mixture ?

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SAND and water
Soil and water
Oil and water
Glucose and water

Answer :D
Discussion
2179.

What are exothermic and endothermic reactions ?

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Solution :REACTIONS in which ENERGY is EVOLVED are called exothermic reactions.
Reactions in which energy is ABSORBED are called endothermic reactions .
Discussion
2180.

Which one of thefollowing is defferent from the others with respect to valency ?

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potassium
ammonium
BARIUM
lithium

Solution :Barium's valncy is 2, whereas the VALENCY of rest of the ELEMENTS is 1.
Discussion
2181.

When sulphuric acid is added to 1g solid sodiumchloride taken in a test tube, which gas is released? What changes do you observe when you test the gas with dry and wet litmus paper? What conclusion do you draw by this experiment?

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Solution :The gas produced is HCL. DRY blue litmus PAPER does not change COLOUR but wet litmus paper changes its colour to red. Dry HCI gas is not acidic but HCI solution is acidic. This is because in the presence of water, HCl dissociates to give `H^+`ions.
`HCl(g) + H_2O(l) to H_3O^(+) " or " H_(AQ)^(+)+ CL^-`
Discussion
2182.

Why are carbon and its compounds used as fuels for most applications?

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Solution :Because these compounds have HIGH CALORIFIC VALUE and LOW ignition temperature.
Discussion
2183.

Two neighbours of homologous series differ by

Answer»

`CH`
`CH_2`
`CH_3`
`CH_4`

SOLUTION :`CH_2`
Discussion
2184.

What are structural isomers? Name the first member of alkanes that show structural isomerism.

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Solution :Molecules that have same chemical formula but different spatial arrangement of their CONSTITUENT atoms are CALLED structural isomers.
The isomers of butane are:
`underset(C_4H_10)underset("Butane")(H-underset(H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-H) "" underset(C_4H_10)underset("Isobutane")(H-underset(H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)underset(H-C-H)underset(|)overset(H)overset(|)(C )-underset(H)underset(|)overset(H)overset(|)(C )-H`
Discussion
2185.

Write the balnced equation for the following chemical reactions : Hydrogen + Chlorine to Hydrogen chloride

Answer»

Solution :Balaced EQUATIONS In the SYMBOLIC from are given as under :
`H_(2)+Cl_(2)to2HCl`
Discussion
2186.

Which law was modified into Modern Periodic law?

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SOLUTION :Mendeleev.s PERIODIC LAW was MODIFIED into MODEM Periodic law.
Discussion
2187.

The value of gram molar mass of CO_(2) is ……………. .

Answer»

44 amu
44 g
44
44 kg

Solution :Hint : MOLAR MASS `=12+(16xx2)=44G`
Discussion
2188.

Write the IUPAC names of thefollowing:CH_3 - undersetoverset(|)(CH_3)(C)H - CH_2 - CH_3

Answer»

SOLUTION :2-Methylbutane
Discussion
2189.

When copper undergoes corrosion the colour of the coating formed on it is

Answer»

silvery
black
REDDISH
GREEN

ANSWER :D
Discussion
2190.

What is meant by the term 'functional group' ?

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SOLUTION :An ATOMS or a group of atoms, which makes a CARBON compound REACTIVE and decides its properties is called a FUNCTIONAL group.
Discussion
2191.

What is the similarity in the valency of all the elements of group 1 in the modern periodic table?

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SOLUTION :VALENCY is same i.e. 1.
Discussion
2192.

What is called homologous series? Give any three of its characteristics?

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Solution :Homologous series is a group or a class of organic COMPOUNDS having same general formula and SIMILAR chemical properties in which the successive members differ by a - `CH_(2)` group.
Characteristics of homologous series
All members of a homologous series CONTAIN the same ELEMENTS and functional group.
All members of a homologous series can be prepared by a common method
Chemical properties of the members of a homologous series are similar.
Discussion
2193.

What happens whenA mixture of ethene and steam is passed over phosphoric acid on silica at 300^@C and 70 atm.

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SOLUTION :`H_2C = CH_2(G) + H_2O(g) OVERSET("phosphoric acid on silica, " 300^@ "70 atm")(to) CH_3CH_2OH `
Discussion
2194.

You want to perform an experiment to study a double displacement reaction in your school laboratory. Name two aqueous solutions required for the experiment. Stare the colour change you are likdy to observe on mix- ing the two solutions.

Answer»

SOLUTION :For ANSWER, CONSULT Q. 10.
Discussion
2195.

Which of the following base is used as antacid to neutralize stomach acidity?

Answer»

`Mg(OH)_2`
`KOH`
`CA(OH)_2`
`NaOH`

ANSWER :A
Discussion
2196.

What happens when dilute hydrochloric acid is added to iron filings? Tick the correct answer.

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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

Answer :A
Discussion
2197.

Which of the following statements is not a correct statement about the trends when going from left to right across the periods of periodic Table.

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The elements BECOME LESS metallic in nature.

Solution :The atoms lose their electrons more EASILY.
Discussion
2198.

Which substance is used in the manufacture of cement ? Write its equation.

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Solution :Calcium oxide (QUICK lime - CaO) is in the manufacture of cement.
`underset("Lime stone")(CaCO_(3)(s)) overset("Thermal DECOMPOSITION")to underset("Quike lime")(CaO(s))+CO_(2)`
Discussion
2199.

What happens when blue vitriol is heated? Explain.

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SOLUTION :Whenbluevitriol( coppersulphatepentahydrate) crystals are gently heated ,it losesit five water MOLECULES and becomes colorless anhydroussulphate .
`UNDERSET("COPPER sulphatepentahydrate (bluecolour )")(CuSO_4 .5H_2 O) underset("COOLING") overset("Hearting")hArr underset("Anhydrous copper sulphate(colourless )")(CuSO_4 +5H_2 O)`
Discussion
2200.

Which of the following is not an inert gas

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Helium
Argon
Bromine
Radon

Answer :C
Discussion