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6101.

Explain the acidic and basic nature of the following substancecs on the basis of protonic concept

Answer»

`H_(2)SO_(4)`
`HPO_(4)^(-2)`
`NH_(3)`
`HN_(4)^(+)`

Solution :(a) `H_(2)SO_(4)` is a proton donor and hence, can act as an acid ACCORDING to protonic CONCEPT
(b) `HPO_(4)^(-2)` can act as a proton donor and form `PO_(4)^(-3)` ion. Therefore, it acts as an acid. `HPO_(4)^(-2)` ion can also accept proton and form `H_(2)PO_(4)^(-)`. Therefore, it acts as a base
(c) `NH_(3)` can act as a proton donor to form `NH_(2)^(-)` and can act as an acid. `NH_(3)` can act as a proton ACCEPTOR to form `NH_(4)^(+)` ion and can act as a base.
(d) `NH_(4)^(+)` can act as a proton donor to form `NH_(3)` and it can act as an acid only
Discussion
6102.

Explain the achievemente ente) of Mendeleev's periodic table.

Answer»

Solution :At the TIME, when Mendeleev classified elements and GAVE his periodic table, he left some gaps for the UNDISCOVERED elements. Thus, many scientists were inspired to discover the unknown elements.
Atomic masses of several elements were corrected on the basis of periodic table.
Inert gases such as helium (He), neon (Ne) and argon (Ar) had been used in many context. These gases were discovered very late because they are very inert and present in EXTREMELY low concentrations in atmosphere. Another strength of the periodic table was that, when these gases were discovered later, they could be placed in a new group named zero group without disturbing the EXISTING order.
Discussion
6103.

Explain substitution reaction in hydrocarbons with an example.

Answer»

Solution :The reaction in which one or more hydrogen atoms of a hydrocarbon are replaced by some other atom is CALLED substitution reaction Substitution reaction are the characteristic property of a SATURATED hydrocarbon (alkanes).
Example: METHANE reacts with chlorine in the presence of SUNLIGHT to form chloromethane and HCI.
`CH_4 + CI_2 OVERSET("Sunlight")(rarr) CH_3 CI + HCI`
Discussion
6104.

Explain smelting process.

Answer»

Solution :Smelting (in a Blast Furnace): The charge consisting of roasted ore, coke and limestone in the ratio 8:4:1 is smelted in a blast furnace by introducing it through the cup and cone arrangement at the TOP. There are three important regions in the furnace.
(a) The Lower Region (Combustion ZONE): The temperature is at `1500^(@)C`. In this region, coke burns with oxygen to form `CO_(2)`when the charge comes in contact with a hot blast of air.
`C + O_(2) underset(Delta)overset(1500^(@)C)to CO_(2)` + Heat
It is an exothermic REACTION since heat is liberated.
(b) The Middle Region (Fusion Zone) The temperatureprevails at `100^(@)C`. In this region, `CO_(2)`
`CO_(2) + C underset(Delta)(overset(1000^(@)C)to 2CO -` Heat
Limesteon decomposes to calcium oxide and `CO_(2)`
`CaCO_(3) underset(Delta)to CaO + CO_(2)` - Heat
These two reactions are enodthermic due to absorption of heat. Calcium oxide combines CaO + `SiO_(2) to CaSiO_(3)`
(c ) The Upper Region (Reduction Zone) - The temperature prevails at `400^(@)C`. In this region carbon MONOXIDE reduces ferric oxide to form a fairly pure spongy iron.
`Fe_(2)O_(3) + 3CO overset(400^(@)C)/(to 2Fe + 3CO_(2)`
The molten iron is collected at the bottom of hte furnance after removing the slag.
The iron thus formed is called pig iron. It is remelted and cast into different moulds. This iron is called cast iron.
Discussion
6105.

Explain smelting process .

Answer»

Solution :Smelting ( in a Blast Furnance ) :
(i) The charge consisting of roasted ore, cok and limestone in the ratio 8:1 .
(ii) Smelted in a blast furnanceby introducingit through the CUP and cone arrangement at the top.
Thereare three important regions in the furnance.

(a) The Lower Region (Combustion Zone ) :
(i) The temperatureis at `1500^(@)C`.
Coke burnswith oxygento form `CO_2` whenthe chargecomesin contact with a hot blastof air .
`C+O_2 underset(Delta)overset(1500^(@)C) to CO_2 +"Heat"`
It is an exothermic reaction since heat is liberated .
(b) The MiddleRegion ( Fusion Zone ) :
(iii) The temperatureprevailsat ` 1000^(@)C`.
(iv) `CO_2` is reduced to ` CO`
`CO_2+C underset(Delta)overset(1000^(@)C)to2CO+"Heat"`
Limestone decomposes to calcium oxide and `CO_2`.
`CaCO_3underset(Delta)toCO_2+"Heat"`
(V) These TWO reactions are endothermicdue to absorption of heat .
(vi) Calcium oxide combineswith silicato form calciumsilicate slag.
`CaO+SiO_2 to CaSiO_2`
(c) The Upper Region ( Reduction Zone ) :
(i) The temperatureprevailsat ` 400^(@)` C .
(ii) Carbonmonoxide reduces ferric oxide to form a fairly PURE spongy IRON.
`Fe_2O_3+3CO overset(400^(@)C) to 2Fe+3CO_2`
The molten iron is collectedat the bottom of the furnanceafter removingthe slag .
(iii) The iron thus formed is called pig iron.
(iv) It'sremelted and cast into different moulds. This iron is called cast iron.
Discussion
6106.

What is saponification?

Answer»

Solution :When esters REACT with strong bases LIKE NaOH or KOH, they form sodium/potassium salt of carboxylic ACID and alcohol. The salt formed is soap. This reaction is CALLED as saponification. Example: `CH_3COOC_2H_4 + NaOH to C_2 H_5OH+`
Discussion
6107.

Explain - sacrificial protection .

Answer»

SOLUTION :Magnesium is more reactive than IRON . When it is COATED on the articles made of STEEL SACRIFICES itself to protect steel .
Discussion
6108.

Explain: Roasting and Calcination

Answer»

Solution :(1) Roasting: In this method, the concentrated sulphide ore is heated in presence of excess of AIR for a long time. `SO_2`metal sulphides ore oxidised to metal oxides and SO2. This method is known as roasting.

(2) Calcination: The ore containing metal carbonate or metal hydroxide is heated strongly in ABSENCE of air to convert it into metal oxide after the removal of volatile impurities and hydrated water. This PROCESS is known as calcination. For example,
`MgCO_3(s) overset(Delta )(to) MgO(s) + CO_2(g)`
`ZnCO_3(s) overset(Delta)(to) ZnO(s) + CO_2(g)`
Discussion
6109.

Explain reactivity series with example.

Answer»

Solution :All metals have different rates of ACTIVITY. Some metals like sodium, potassium, calcium, etc. are highly reactive. These metals combine with oxygen to form oxide and react with hydrogen to form hydrides. Some metals are comparatively less reactive e.g. IRON, zinc, etc. Some metals are least reactive e.g. Gold, Silver. Reactivity of metals DEPENDS on their ability to loose electrons Metals are arranged in a list in DECREASING rates of their activity.
Discussion
6110.

Explain : Oxidation of alcohol

Answer»

Solution :CARBON compounds can easily be oxidised. Combustion is also an example of vigorous OXIDATION.
Alkaline potassium permanganate or acidified potassium dichromate oxidise ETHANOL to acetic acid.
Reaction equation :
(1) `underset("Ethanol")(CH_(3)CH_(2)OH) overset("Alkaline "KMnO_(4)+" Heat")underset("or Acidic "K_(2)Cr_(2)O_(7)+" Heat")to underset(("Ethanoic acid"))underset("Acetic acid")(CH_(3)COOH)`
(2) `underset("PROPANOL")(CH_(3)CH_(2)CH_(2)OH)overset("Alkaline "KMnO_(4)+" Heat")underset({:("OR"),("Acicid "K_(2)Cr_(2)O_(7)+" Heat"):})to underset("Propanoic acid")(CH_(3)CH_(2)COOH)`
Discussion
6111.

Explain : Mechanism of micelle formation.

Answer»

Solution :The molecules of SOAP are sodium or POTASSIUM salts of long chain carboxylic acids.
Two ends of soap molecule possess different properties. One end is hydrophilic and it dissolves in water, while the other end is hydrophobic and it dissolves in hydrocarbons.
When soap is at the SURFACE of water, the hydrophobic TAIL of soap will not be soluble in water and the soap will align along the surface of water with the ionic end in water and the hydrocarbon .tail protruding out of water.

Inside water, these molecules have a PARTICULAR orientation that keeps the hydrocarbon portion out of the water.
This happens due to the formation of clusters of molecules in which the hydrophobic tails are in the interior part of the cluster and the ionic ends are on the surface of the cluster.
This formation is called a micelle.
Soap in the form of a micelle collects the oily dirt in the centre of it and is able to clean.
These micelles exist in solution as a colloid.
Micelles do not cluster to precipitate because of ion-ion repulsion.
Thus, the dirt suspended in the micelles is also easily rinsed away.
The soap micelles are large enough to scatter light, hence a soap solution appears cloudy.
Discussion
6112.

Explain the meanings of malleable and ductile.

Answer»

Solution :MALLEABLE: Substance that can be beaten into THIN sheets are called malleable.
For EXAMPLE: Most of the metals are malleable.
DUCTILE: Substance that can be drawn into thin wires are called ductile.
For example: Most of the metals are ductile.
Discussion
6113.

Explain in detail the Nomenclature of Carbon compounds.

Answer»

Solution :The names of COMPOUNDS in a homologous series are based on the name of basic carbon chain modified by a .PREFIX. phrase before or .suffix. .phrase after. indicating the nature of the functional group. For example, the names of various alcohols are methanol ETHANOL, propanol and butanol.
Naming of carbon compounds can be done by the following method :
(i) IDENTIFY the number of carbon atoms in the compound. A compound having three carbon atoms will have the name propane.
(ii) In case a functional group is present, it is indicated in the name of the compound with either a .prefix. or a .suffix.. Like CHLORO propane, bromo propane, propanal propanone etc.
(iii) If the name of functional group is to be given on the basis of suffix, the name of the carbon chain is modified by deleting the final .e. and adding theappropriate suffix. For example, a chain having three carbons with a Ketone group will be given name in the following manner.
Propane - .e. = Propane + .one. = Propanone.
(iv) If the carbon chain is unsaturated them the final .ane. in the name of carbon chain is substituted by .ene. or .yne.. For example, a three-carbon chain with a double bond would be called propene and if it has triple bond. It would called propyne.
Discussion
6114.

Explain in brief : The method of nomenclatureof carbon compounds.

Answer»

Solution :The method of nomenclature of the carbon compounds can be done by the following rules :
(1) The longest straight chain of carbon atoms in the given compound is identified first, then alkane root name is selected. (It is called parent hydrocarbon.)

(2) In case if a functional group is present, it is indicated in the name of the compound with EITHER a prefix or a suffix (as given in the following Table.)

(3) If the name of the functional group is to be given as a suffix, and the suffix of the functional group begins with a vowel a, e, i, o, u, then the name of the carbon chain is modified by deleting the final .e. and adding the appropriate suffix.
For example, a three-carbon chain with a ketone group would be named in the following manner :
Propane - .e. = propan + .-one. = propanone
(4) If the carbon chain is unsaturated, then the final .ane. in the name of the carbon chain is substituted by .-ene. or .-yne. as given in the above Table.
For example, a three-carbon chain with a DOUBLE bond would be called propene and if it has a triple bond, it would be called propyne.
(5) The position of the functional group in the carbon chain should be given by the lowest possible numeral (number) either from left and or RIGHT end.
Discussion
6115.

Explain how the tidal energy is harnessed and write one limitation of the use of tidal energy.

Answer»

Solution :Tidal energy is HARNESSED by constucting a dam near the shore. During the HIGH tidel water flows into the dam during the low TIDES later flows out this FLOWING water roatest the TURBINE present at the opening of the dam and produces electricity.
Discussion
6116.

Explain how the properties of an alloy are different from those of constituent metals.

Answer»

Solution :(i) Alloys are stronger and harder than the CONSTITUENT metals.
(ii) Alloys are more resistant to CORROSION.
(III) Alloys have LOWER melting point than the constituent metals.
(iv) Alloys have lower electrical conductivity than pure metals.
Discussion
6117.

Explain how the following metals are obtained from their compounds by the reduction process? Metal Z which is high up in the reactivity series. Give one example of each type.

Answer»

Solution :Metal Z, which is HIGH up in the activity series, is ISOLATED by electrolytic reduction of its MOLTEN chloride. Metals like NA, MG are isolated by electrolytic reduction of their molten chlorides.
Discussion
6118.

Explain how the following metals are obtained from their compounds by the reduction process? Metal Y which is in the middle of the reactivity series. Give one example of each type.

Answer»

Solution :Metal Y, which is in the middle of the activity series, is obtained by the reduction of its oxide by CARBON. Metals LIKE Zn, Fe are isolated by the reduction of their OXIDES with carbon
Discussion
6119.

Explain how the following metals are obtained from their compound by the reduction process: (a) Metal M which is in the middle of the reactivity series. (b) Metal N which is high up in the reactivity series Give one example of each type.

Answer»

Solution :(a) The metal M which is the middle of the reactivity series (such as iron,zinc,lead,copper,etc) is moderately reactive, So for obtaining such metals from their compounds, their sulphides and carbonates (in which they are PRESENT in nature) are first converted into their oxides by the process of roasting and calcination respectively.
For example,
`2ZnS(s)_(Zinc sulphide)+3O_2(g) to^(HEAT) 2ZnO(s)+2SO_2(g)`
`ZnCO_3(s)_(Zinc carbonate) to^(Heat) ZnO(s)+CO_2(g)`
the metal oxides (MO) are then reduced to the corresponding metals by using suitable reducing agents such as carbon. For example, zinc metal from its oxide is obtained as follow:
`ZnO(s)_(Zinc oxide)+C(s) to Zn(s)_(Zinc)+CO(g)`
(b) The metal N which is high up in the reactivity series (such as sodium, magnesium, calcium, aluminium etc.) is very reactive and cannot be obtained from its compound by HEATING with carbon.
Therefore, such metals are obtained by ELECTROLYTIC reduction of their molten salt. For example, sodium is contained by the electrolysis of molten sodium chloride (NaCl).
At cathode: `NA^+ + e^(-) to Na`
At anode: `2Cl^(-) to Cl_2 +2e^(-)`
Discussion
6120.

Explain how the following metals are obtained from their compounds by the reduction process? Metal X which is low in the reactivity series.Give one example

Answer»

Solution :METAL X, which is LOW in the ACTIVITY series, is OBTAINED by heating its ore. Mercury is obtained by heating cinnabar (HgS).
Discussion
6121.

Explain how the following metal are obtained from their compounds by reduction process? Metal Z which is high up in the reactivity series.

Answer»

Solution :Metal Z, which is high up in the reactivity series, is ISOLATED by electrolytic reduction of its molten chloride. Metals LIKE NA and Mg are isolated by electrolytic reduction of their molten chlorides.
Discussion
6122.

Explain how the following metal are obtained from their compounds by reduction process? Metal Y which is in the middle of the reactivity series.Give one example of each type.

Answer»

Solution :METAL Y, which is in the middle of the REACTIVITY series, is obtained by the reduction of its oxide by CARBON. Metals LIKE Zn and Fe are isolated by the reduction of their oxides with carbon.
Discussion
6123.

Explain how the following metal are obtained from their compounds by reduction process? Metal X which is low in the reactivity series.Give one example of each type.

Answer»

Solution :Metal X, which is LOW in the reactivity SERIES, is obtained by heating its ORE. Mercury is obtained by heating cinnabar (HGS).
Discussion
6124.

Explain how sexual reproduction gives rise to more viable variations than asexual reproduction. How does this affect the evolution of those organisms that reproduce sexually?

Answer»

SOLUTION :SEXUAL reproduction cause more viable variation due to the following reasons:
Error in copying of DNA, which are not highly SIGNIFICANT .
Random segregation of paternal and maternal chromosomes at the time of gamete formation.
Exchange of genetic material between homologous chromosomes during formation of gamets.
Accumulation of variations occured due to sexual reproduction over generation after generation of selection by nature created wide diversity.
In case of sexual reproduction, only the very small changes due to inaccuracies in DNA copying pass on to the progency. Thus offsprings of a sexual reproduction are more or LESS genetically similar to their parents so it can be concluded that evolution in sexually reproducing organisms proceeds at a faster PACE than in sexually reproducing organisms.
Discussion
6125.

How can the change in pH in the river water affect the living organisms ?

Answer»

Solution :If PH of river water CHANGES, AMOUNT of oxygen DISSOLVED in water MAY decreases. Acidic and basic water is harmful for skin of aquatic animals like fish.
Discussion
6126.

Explain how Avogadro hypothesis used to derive the value of atomicity.

Answer»

SOLUTION :(i) The Avogadro.s law states that ..equal volumes of all gases under similar conditions of temperateure and pressure contain equal number of molecules...
(ii) LET us consider the reaction between hydrogen and chlorine to form hydrogen chloride gas.
`underset("1 volume")(H_(2(g)))+underset("1 volume")(Cl_(2(g)))rarr underset("2 volumes")(2HCl_((g)))`
(iii) ACCORDING to Avogadro.s law, 1 volume of any gas is occupied by ..n.. number of molecules.
`..n.." molecules"+..n.." molecules"rarr "..2N.. molecule"`
If `..n.. = 1`, then
`"1 molecule "+"1 molecule"rarr"2 molecules."`
`1//2" molecules"+1//2" molecule"rarr"1 molecule"`
(iv) 1 molecule of hydrogen chloride gas is made up of `1//2` molecule of hydrogen and `1//2` molecule of chlorine.
(v) `1//2` molecule of hydrogen contains 1 atom.
So, 1 molecule of hydrogen contains 1 atoms.
So, 1 molecule of hydrogen contains 2 atoms.
So, hydrogen atomicity is 2. Similarly chlorine atomicity is also 2. So, `H_(2) and Cl_(2)` are diatomic molecules.
Discussion
6127.

Explain the nature of covalent bond using the bond formation in CH_3Cl

Answer»

Solution :The structure of `CH_(3)CL` is given below

Carbon had FOUR valence electron .It shares 1 electron each with 3 Hydrogen atoms and 1 electron with chlorine.The bond between C and Cl atoms is covant but due to HIGHER value of electro negetivity of Cl ,the C-Cl bond is POLAR in nature
Discussion
6128.

Explain Gravity separation method.

Answer»

Solution : Gravity Separation (or) HYDRAULIC method: Principle: The DIFFERENCE in the DENSITIES or specific gravities of the ore and the gangue is the main principle behind this method.Oxide ores are purified by this method.eg .. Haematite Fe, O, the ore of iron.Method: The ore is poured over a sloping, vibrating corrugated table with grooves and a jet of water is allowed to flow over it.The DENSER ore particles settle down in the grooves and lighter gangue particles are WASHED down by water.
Discussion
6129.

Explain Froth floatation process.

Answer»

Solution : Froth floatation process: Principle: This process depends on the PREFERENTIAL wettability of the ore with oil (pine oil) and the gangue PARTICLES by water . Lighter ores , such as sulphide ores , are CONCENTRATED by this method e.g Zinc blende (ZnZ)
Methods the ushed ore is TAKEN in a large tank 1.::::: containing oil and water and agitated with a current of compressed air.The ore is wetted by the oil and gets separated from the gangue in the form of froth.Since the ore is lighter, it comes on the surface with the froth and Gangue the impurities are left BEHIND. .e.g.Zinc blende (ZnS).
Discussion
6130.

Explain : Chemical reactions of ethanol

Answer»

SOLUTION :Chemical reactions (properties) of ethanol are as follows:
(1) Reaction of ethanol (alcohol) with sodium metal : Reaction of - OH group of ethanol with sodium metal produces sodium ethoxide and hydrogen gas.
`UNDERSET("Sodium")(2NA)+underset("Ethanol")(2CH_(3)CH_(2)OH)tounderset("Sodium ethoxide")(2CH_(3)CH_(2)O^(-)Na^(+))underset("gas")underset("Hydrogen")(+" "H_(2))`
( 2 ) Reaction of ethanol with concentrated sulphuric acid (Dehydration of alcohol) : When ethanol is heated with excess of concentrated sulphuric acid at 443 K, it forms ethene due to dehydration of ethanol.

Here, concentrated sulphuric acid acts as a dehydrating agent.
Discussion
6131.

Explain Bessemerisation.

Answer»

SOLUTION :Bessermerisation :
(i) The moltenmatteis transferred to Bessemer converterin ORDER toobtain blister copper .
(II) Ferrous sulphide from matter is OXIDIZED to ferrous oxide, which is removed as slag using silica.
`2 Fe S+ 3O_2 to 2FeO+ 2SO_2 uarr`
` FeO+ SiO_2 to UNDERSET("(Iron silicate )")(FeSiO_3)`(slag)
`2Cu_2S + 3O_2 to 2Cu_2O + 2SO_2 uarr `
`2Cu_2O+Cu_2S to underset("(Blister copper )")(6Cu)+SO_2 uarr `
Discussion
6132.

Explain : Alloying of gold

Answer»

Solution :Pure gold (24 carats) is very soft and so the jewellery or ornaments MADE from it do not resist much pressure. Even a little pressure can change their shape. Moreover they cannot resist much of wear and tear caused by friction. So, gold is ALLOYED with other metals like copper and SILVER to make it hard. 22 CARAT gold means it contains 22 parts of gold and 2 parts copper or silver in 24 parts by WEIGHT of an alloy.
Discussion
6133.

Explain : Addition reaction

Answer»

Solution :A reaction in which another MOLECULE is ADDED to an organic compound to FORM a new organic compound is known as an addition reaction.
OR
A reaction in which two reactants combine to form a single product is known as an addition reaction.
Unsaturated hydrocarbons add hydrogen in the presence of catalysts such as palladium or nickel to form saturated hydrocarbons.

This reaction is commonly used in the hydrogenation of vegetable oils using a nickel catalyst.
Vegetable oils possesses long unsaturated CARBON chains while animal fats possesses saturated carbon chains, hence, vegetable oils are good for health
Animal fats generally contain saturated fatty acids which are SAID to be harmful for health.
Discussion
6134.

Explain : (a) Why copper is used to make taps, hot water tanks and not any other metal ? (b) What will happen, if iron nails are kept in a solution containing copper sulphate ? (c) Write the balanced chemical equations for the following and balance it:(i) Ca + H_2O to(ii) Al + HCl to(iii) Fe + H_2O to

Answer»

Solution :(a) Copper does not react with cold and hot water, nor it reacts with the steam of water. Moreover, it is cheap and EASILY available, HENCE, it is used to make taps and hot water TANKS. (b) When iron nails are kept in a copper sulphate solution, the blue COLOUR of the solution fades due to displacement of copper by iron.
(c) `(i) Ca + 2H_2O to Ca(OH)_2 + H_2(g)`
`(ii) 2Al + 6HCl to 2AlCl_3 + 3H_2(g)`
`(iii) 3Fe + 4H_2O to Fe_3O_4 + 4H_2(g)`
Discussion
6135.

Expain the role of aluminium in the extraction of chromium or manganese.

Answer»

SOLUTION :(i) Reactivity of ALUMINIUM.
(ii)The reaction that the ore should undrgo in the extraction of metal.
(III) Chemical PROPERTY of aluminium that is exploited to EXTRACT the metal from its ore.
Discussion
6136.

Expain the action of air with iron .

Answer»

Solution : `3Fe+2O_(2)rightarrow Fr_(3)O_(4)`
MAGNETIC OXIDE (Black)
Discussion
6137.

Except noble gases, atoms, of most of the elements are found in the combined form.

Answer»


ANSWER :1
Discussion
6138.

Except ………….atoms of most of the elements are found in the combined form with itself or atoms of other elements.

Answer»

SOLUTION :NOBLE GASES
Discussion
6139.

Example for liquid in liquid binary solution is ………

Answer»

COPPER dissolved in GOLD
Water VAPOUR in air
Ethyl alcohol dissolved in water
NaCl dissolved in water

SOLUTION :Ethyl alcohol dissolved in water
Discussion
6140.

Example for liquid in solid type solution is ...

Answer»

SOLUTION :SODIUM CHLORIDE DISSOLVED in WATER
Discussion
6141.

Examine the elements of the third period and classify them as metals or non-metals. Comment on the metallic and non-metallic character of the third period. Name the most metallic element and non-metallic element of this period.

Answer»

Solution :Na (Sodium), Mg (Magnesium) and Al (Aluminium) are metals. SI (Silicon) is a metalloid. P (Phosphorus), S (SULPHUR) and Cl (Chlorine) are non-metals. 142 As we go from LEFT to right across the third PERIOD, metallic character decreases and non-metallic character increases.
The most metallic element in the third period is Na and the most non-metallic element is Cl.
Discussion
6142.

Examine elements of the third period and classify them as metals and non-metals.

Answer»

Solution :FIRST, electronic configuration of these ELEMENTS is WRITTEN to find the NUMBER of valnece electrons. The elements having 1 - 3 valence electrons are metals while the elements having 4 - 8 valence electrons are non-metal.
Discussion
6143.

Every period of the periodic table (except first period) starts with a member of alkali metal.(T/F)

Answer»


ANSWER :TRUE
Discussion
6144.

Ethyne undergoes addition reaction. State one reason.

Answer»

SOLUTION : Because ethyne `(HC -= CH) ` is unsaturated hydrocarbon INVOLVING a triple BOND.
Discussion
6145.

Ethyne gives a white precipitate with ammoniacal solution of ___. (AgNO_3//NaCl)

Answer»

SOLUTION :`AgNO_3`
Discussion
6146.

Ethyne (C_2H_2)is unsaturated hydrocarbon. Explain.

Answer»

Solution :ETHYNE molecule has TRIPLE bond `(C -= C)`, it DECOLOURISES bromine solution and forms a red precipitate with ammoniacal COPPER (I) CHLORIDE.
Discussion
6147.

Ethyl ethanoate smells like pears and is used for flavouring sweets. a] Write the chemical formula of ethyl ethanoate. b] Write the chemical reaction between ethanol and ethanoic acid in the presence of sulphuric acid. c] Suggest the function of sulphuric acid in the reaction.

Answer»

SOLUTION :a] `CH_3COOC_2H_5`.
b]
c] Sulphuric ACID ACIS as a catalyst.
Discussion
6148.

E^(theta) for CI_(2)(g)+2I^(-) rarr 2CI^(-) (aq.) is 1.36 V,then calculate. E^(theta) for 4CI^(-)(aq) rarr2CI^(-)(g)+4e^(-)

Answer»

Solution :`E_(CI^(-)//CI_(2))^(theta) =-1.36` is independent of AMOUNT of substance
Discussion
6149.

Ether act as universal solvent.

Answer»


SOLUTION :Correct statement: WATER act as universal SOLVENT.
Discussion
6150.

Ethene is formed when ethanol at 443 K is heated with excess of concentrated sulphuric acid. What is the role of sulphuric acid in this reaction? Write the balanced chemical equation of this reaction.

Answer»

SOLUTION :Sulphuric acid acts as a dehydrating agent.
`CH_(3)CH_(2)OH underset(443K) overset("Hot conc. "H_(2)SO_(4))to CH_(2)=CH_(2)+H_(2)O`
Discussion