Description : Why are Ti+2 and other transition metals and their ions paramagnetic ?
Last Answer : Ans: These ions have unpaired electrons in d- subshell.
Description : Why do transition metals have higher I.E than s –block elements ?
Last Answer : Ans: It is due to smaller atomic size than s-block elements , effective nuclear charge is more , terefore I.E is high.
Description : Why is K2Cr2O7 generally preferred over Na2Cr2O7 in a volumetric analysis .Give reason .
Last Answer : Ans : It is because Na2Cr2O7 is hygroscopic in nature that is why it absorbs moisture from atmosphere , therefore its standard solution can not be prepared .
Description : Explain the following , giving reason . (a) Transition metal and many of their compounds show paramagnetic behavior (b) The enthalpy of atomisation of the transition metal is high . (c) The Transition metal generally form coloured compounds .
Last Answer : Ans(a) It is due to unpaired electrons . (b) It is due to strong metallic bond and additional Covalent bonds due to presence of unpaired electron in d- orbitals (c) It is due to presence of unpaired electrons ,they undergo d-d transition .
Description : Why are lanthanoid colored and paramagnetic L
Last Answer : Ans It is due to presence of unpaired electrons, they are paramagnetic and they absorb light From visible region and undergoes f-f transition and radiate complementary colour .
Description : Why Mn+2 is more stable than Mn+3 but Fe +3 is more stable than Fe+2 ?
Last Answer : Ans Mn+2 has half filled d- orbital ,therefore it is more stable than Mn+3 Fe+3 has half filled d- orbital, therefore it is more stable than Fe +2 .
Description : Why are transition metal fluorides are ionic in nature where as chlorides and bromides are covalent in nature .
Last Answer : Ans - It is because of fluorine is most electronegative where as Cl and Br are less electro negative . Greater the difference in electro negativity more will be ionic character .
Description : Why is Cu+1 diamagnetic and Cu +2 paramagnetic ?
Last Answer : It is because Cu+ does not have unpaired electrons where as Cu+2 has unpaired electrons in d-sub cell .
Description : Why do Zr and Hf show similar properties ?
Last Answer : Ans It is due to similar ionic size which due to lanthanide contraction .
Description : Why are Cr+ , Ag+ & Sc+3 Colour less ?
Last Answer : Ans It is because they do not have unpaired electrons ,therefore can not under goes d-d transition .
Description : Why are transition metals and there compounds generally coloured ?
Last Answer : Ans It is due to present of unpaired electrons in transition metals and their ions , that is why they absorbed light from visible region and undergoes d-d transition and radiate complementary colour .
Description : What is an lanthanoid contraction ? What is its cause ? Give its consequences .
Last Answer : Ans The decrease in atomic and ionic size with increase in atomic no. in lanthanoid series is called lanthanoid contraction . The cause of lanthanoid contraction is poor shielding effect of d and f ... is close resemblance between elements of 4 d and 5 d transition series . due to similar ionic
Description : Why Ce+3 Can be easily Oxidised to Ce+4 ?
Last Answer : Ans : It is because Ce+4 has stable electronic configuration .
Description : Why do transition metals have high enthalpy of atomization ?
Last Answer : Ans : it is due to strong metallic bonds and additional covalent bonds
Description : What is the highest oxidation state shown by Cr. (24) , Mn(25) ?
Last Answer : Ans: Cr. Shows (+6) and Mn Shows (+7) Oxidation state .
Description : Why are Zn , Cd , Hg are not regarded as transition metals ?
Last Answer : Ans: It is because neither they nor their ions have incompletely filled d- orbitals .
Description : What are d Block Elements ?
Last Answer : Ans: Those elements in which d-orbital are progressively filled up are known as d-orbital.
Description : Application of d- & f- block elements
Last Answer : Application of d- & f- block elements:- 1. Iron and steel used in construction,as catalyst in Haber's process 2. CrO2 is used in magnetic tapes 3. Ni is in hydrogenation 4. W ( ... in contact process 9. Titanium is in nuclear reactions. 10. PdCl2 is in Wacker's process.
Description : The catalyst used in hydrogenation of oils is - (1) Fe (2) V2O5 (3) Ni (4) O2
Last Answer : (3) Ni Explanation: The catalyst used in hydrogenation of oils is nickel. It is used to speed up the reaction. Vegetable oils convert into vanaspati after hydrogenation.
Description : Low pressure Zeigler process for the manufacture of polythene uses a catalyst which is (A) Ni (B) V2O5 (C) Fe (D) Aluminium triethyl combined with titanium tetrachloride
Last Answer : (D) Aluminium triethyl combined with titanium tetrachloride
Description : Promoter used in NH3 synthesis catalyst is (A) K2O (B) SiO3 (C) V2O5 (D) U2O3
Last Answer : (C) V2O5
Description : __________ is used as a catalyst in fat splitting. (A) ZnO (B) Ni (C) V2O5 (D) FeO
Last Answer : (A) ZnO
Description : In multistage equilibrium conversion of SO2 to SO3 (2SO2 + O2 ⇌ 2SO3 ), the reverse reaction becomes appreciable at a temperature of 550° C. The percentage equilibrium conversion of SO2 to ... some quantity of SO3 during intermediate stage (D) Maintaining low temperature & pressure in the converter
Last Answer : (C) Removing some quantity of SO3 during intermediate stage
Description : Catalyst used in the manufacture of sulphuric acid by chamber & contact processes are respectively (A) V2O5 & Cr2O3 . (B) Oxides of nitrogen & Cr2O3 (C) V2O5 on a porous carrier & oxides of nitrogen (D) Oxides of nitrogen & V2O5 on a porous carrier
Last Answer : (D) Oxides of nitrogen & V2O5 on a porous carrier
Description : Catalyst used in the oxidation of benzene to produce Maleic anhydride is (A) V2O5 (B) Pt (C) Ni (D) Cr
Last Answer : (A) V2O5
Description : Manufacture of phthalic anhydride uses __________ as a catalyst. (A) Ni (B) Cr (C) V2O5 (D) Al2O3
Description : Anthracene undergoes oxidation with O2/V2O5 at 500°C to give (a) Benzoic acid (b) Anthraquinone (c) Phthalic acid (d) Benzophenone
Last Answer : Anthraquinone
Description : Which reagent is used for conversion of benzaldehyde into toluene? a. KMnO4/NaOH b. NH2NH2/KOH c. HIO4 d. V2O5
Last Answer : b. NH2NH2/KOH
Description : Soap helps in better cleaning of clothes because - (1) Soap acts like catalyst (2) It reduces the surface tension of solution (3) It gives strength to solution (4) It absorbs the dirt
Last Answer : (2) It reduces the surface tension of solution Explanation: Soaps are effective cleaners because they can dissolve and the oil and grease that holds dirt in place. They reduce the surface tension of the ... surfactant molecules help water to get a hold of grease, break it up, and wash it away.
Description : Soap helps in better cleaning of clothes because (1) Soap acts like catalyst (2) It reduces the surface tension of solution (3) It gives strength to solution (4) It absorbs the dirt
Last Answer : It reduces the surface tension of solution
Description : What is it about the shower that acts as such a strong catalyst for good ideas?
Last Answer : I guess that the hot steam clears your head.
Description : Which one of the following also acts as a catalyst in a bacterial cell? (a) 5S rRNA (b) snRNA (c) hnRNA (d) 23S rRNA
Last Answer : (a) 5S rRNA
Last Answer : 23S rRNA
Description : A reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction. (A) Catalytic (B) Autocatalytic (C) Photochemical
Last Answer : (C) Photochemical
Description : In autocatalytic reactions, (A) One of the reactants acts as a catalyst (B) One of the products acts as a catalyst (C) Catalysts have very high selectivity (D) No catalyst is used
Last Answer : (B) One of the products acts as a catalyst
Description : The reaction in which one of the products of reaction acts as a catalyst is called a/an __________ reaction. (A) Biochemical (B) Photochemical (C) Catalytic (D) Autocatalytic
Last Answer : (D) Autocatalytic
Description : A catalyst promoter (A) Improves the activity of a catalyst (B) Acts as a catalyst support (C) Itself has very high activity (D) All (A), (B) and (C)
Last Answer : (A) Improves the activity of a catalyst
Description : A bio-catalyst produced by living cells which acts independent of the cell is called a/an (A) Substrate (B) Enzyme (C) Nutrient (D) None of these
Last Answer : (B) Enzyme
Description : A mixture of chlorine & sodium bromide acts as a/an (A) Insecticides (B) Analgesic drug (C) Fire retardant (D) Hydrogenation catalyst
Last Answer : (C) Fire retardant
Description : In stratosphere, which of the following element acts as a catalyst in degradation of ozone a release of molecular oxygen ? (1) Carbon (2) Cl (3) Fe (4) Oxygen
Last Answer : (2) Cl
Description : What is Phyto Hormone Catalyst ?
Last Answer : Answer : Phyto Hormone Catalyst is an organic catalyst that converts soil organic matter into food juice. This is a catalyst for compatibility with soil and its compounds.
Description : What is Catalyst Poison ?
Last Answer : Substances that reduce or even stop the catalytic ability of catalysts are called catalysts. Usually catalysts such as dust , sulfur powder , As2O3, etc. act as toxins.
Description : What is an inequality catalyst ?
Last Answer : A catalyst is an asymmetric catalyst in which the participating objects and the physical state of the catalyst differ.
Description : What is a homogeneous catalyst ?
Last Answer : If the phase of the catalyst and the reactant are the same, the present catalyst is called homogeneous catalyst.
Description : What is a negative catalyst ?
Last Answer : A catalyst that slows down a chemical reaction is called a negative catalyst.
Description : What is a positive catalyst ?
Last Answer : A catalyst in the presence of which the speed of a chemical reaction increases is called a positive catalyst.
Description : (4) None of these Explanation: Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that ... may participate in multiple chemical transformations. Catalysts that speed the reaction are called positive catalysts.
Last Answer : Table salt gets moist during rainy season because – (1) sodium chloride is hygroscopic (2) sodium chloride is deliquescent (3) sodium chloride contains some quantity of sodium iodide (4) sodium chloride contains hygroscopic impurities like magnesium chloride
Description : The metal that is used as a catalyst in the hydrogenation of oils is - (1) Pb (2) Ni (3) Cu (4) Pt
Last Answer : (2) Ni Explanation: The catalyst used in hydrogenation of oils is nickel. It is used to speed up the reaction.
Description : Which among the following is used as a catalyst in the production of high octane fuels? (1) HNO3 (2) H2SO4 (3) HCl (4) HF
Last Answer : (2) H2SO4 Explanation: Sulfuric acid is used as a catalyst for refining and for producing alkylate, an essential component of highoctane fuel. The hydrocarbon molecules are reformed into more complex molecules with a higher octane rating value.
Description : Freon is used as - (1) Oxidant (2) Refrigerant (3) Catalyst (4) Both (1) and (2)
Last Answer : (2) Refrigerant Explanation: Freon uses for a number of halocarbon products. They are stable, nonflammable, moderately toxic gases or liquids which have typically been used as refrigerants and as aerosol propellants.