Description : Which aerosol deplete ozone layer ?
Last Answer : Ans C.F.C
Description : Write the formula of tear gas .
Last Answer : Ans : CCl3 NO2
Description : Why is helium used in diving apparatus ?
Last Answer : Ans: Because heliun is very low solubility in blood
Description : Why H3 PO3 is dibasic and H3PO4 is tribasic ?
Last Answer : Ans In H3PO3 only two replacable hydrogen but inH3PO4 , three hydrogens are replacable .
Description : How is the presence of SO2 detected ?
Last Answer : Ans : 1. It has pungent characteristic smell . 2. It decolourises KMn O4 solution 3. It turns acidified K2 Cr2 O7 green
Description : Why is fluorine stronger Oxidising agent ?
Last Answer : Ans: Due to (a) Low enthalpy of dissociation (b) high enthalpy of Hydration of F-
Description : Halogens have maximum negative electron gain enthalpy in the respective periods in the P. T Why ?
Last Answer : Ans Due to smallest size and high effective nuclear charge , readily accept one electron to acquire noble gas electronic configuration
Description : Which forms of Sulphur show paramagnetic behaviour ?
Last Answer : Ans : In Vapour State sulphurPartly exists as S2 molecule which has two unpaired electrons in the * Orbitals hence exhibit paramagnetic
Description : Give reasons i) H2O is a liquid but H2S a gas. ii) Ammonia has higher boiling point than phosphine ii) Krypton & xenon make compounds.
Last Answer : Ans: i) Hydrogen bond is found in H2O but not in H2S. ii) Hydrogen bond is found in NH3 but not in PH3. iii) Because they have low ionization energy.
Description : Find hybridization and shape i) XeF2 ii) XeO3 iii) XeF4
Last Answer : Ans: i) sp3d, Linear ii) sp3, Pyramidal iii) sp3d2 , Square planar
Description : How is ammonia prepared? Write chemical reaction involved in the Haber’s process.
Last Answer : i) Ammonia is prepared by the combination of hydrogen and nitrogen in the ratio of 3:1. ii) The used catalyst is iron oxide. The promotors are potassium and aluminium oxides. iii) The required conditions are high pressure and moderate temperature. N2 + 3H2 → 2NH3
Description : Nitrogen shows anomalous behaviour in the group. Why?
Last Answer : Ans: i) Small size ii) High electro negativity iii) Absence of vacant d-orbital.
Description : Give reasons: a) Phosphorous pentachloride is unstable. b) Phosphorous trichloride fumes in moisture.
Last Answer : Ans: a) Because of two longer axial bonds. b) Because it reacts with water and forms hydrochloric acid.
Description : Ortho phosphoric acid is triprotic but phosphoric acid is diprotic. Why?
Last Answer : Ans: Because of their structures ortho phosphoric acid and phosphoric acid have three and two ionisable hydrogen.
Description : Write shape of following molecules: a) Ammonia b) Phosphorous Pentachloride
Last Answer : Ans: a) Pyramidal b) Trigonal bipyramidal
Description : Ammonia is water soluble. Why?
Last Answer : Ans: It forms hydrogen bond with water.
Description : Why is Nitrogen relatively inert?
Last Answer : Ans: Because of a triple bond with high bond energy.
Description : Why Nitrogen is a gas whereas Phosphorous is a solid?
Last Answer : Ans: Nitrogen molecules have less Vander Waal’s forces of attraction whereas molecular phosphorous has more Vander Waal’s forces of attraction.
Description : Why is Ammonia a good complexing agent?
Last Answer : Ans: Because of lone pair of electrons on N.
Description : Why is phosphine weaker base than Ammonia?
Last Answer : Ans: P is bigger than N, therefore lone pair of electrons are less available on P than N.
Description : For which molecule can the bonding be described in terms of sp3 hybrid orbitals of the central atom? w) CH4 x) SF6 y) BF3 z) PCL5
Last Answer : ANSWER: B -- CH4
Description : What happens to the dissociation of PCl5 in a closed vessel if He gas is introduced into it at the same temperature?
Last Answer : Ans. No effect.
Description : Explain why PCl5 is trigonal bipyramidal and IF5is square pyramidal?
Last Answer : Ans. PCl5 has 5 bond pairs of electrons around central atom while in IF5 there are 5 bond pair & 1 lone pair of electrons around central atom.
Description : Compound (A) when reacted with PCl5 and then with ammonia gave (B). Compound (B) when treated with bromine and NaOH, produced (C). Compound (C) on treatment with NaNO2/HCl at 0°C and then boiling with H2O ... Compound (A) is (a) o-Toluic acid (b) o-Chlorotoluene (c) m-Toluic acid (d) o-Bromotoluene
Last Answer : o-Toluic acid
Description : Which of the following compounds will react with PCl5 least vigorously? (a) Ethanol (b) Acetic acid (c) Phenol (d) Benzoic acid
Last Answer : Phenol
Description : Which of the following reagents will react with acetamide to form methylamine? (a) LiAlH4 (b) Br2/NaOH (c) PCl5 (d) H2/Ni
Last Answer : Br2/NaOH
Description : Acetamide can be converted into methylamine by (a) P2O5 (b) Br2/NaOH (c) PCl5 (d) LiAlH4
Description : Butyric acid reacts with PCl5 to give (a) Benzoyl chloride (b) 1-Chlorobutane (c) Butyryl chloride (d) 1-Chloropropane
Last Answer : Butyryl chloride
Description : Organic compound (A), C4H8O, does not react with sodium or PCl5. However, it reduces an alkaline solution of a copper (II) salt on heating. Compound (A) could be (a) an aldehyde (b) a primary alcohol (c) a ketone (d) a secondary alcohol
Last Answer : an aldehyde
Description : Ethylene glycol reacts with excess of PCl5 to give (a) Chloroethane (b) 1,2-Dichloroethane (c) Hexachloroethane (d) 1,3-Dichloroethane
Last Answer : 1,2-Dichloroethane
Description : Which of the following reaction mixtures will give an organic product which is ionic? (a) CH3CH2OH + PCl5 (b) CH3CH2OH + KBr + H2SO4 (c) CH3CH2OH + Na (d) CH3CH2OH + SOCl2
Last Answer : CH3CH2OH + Na
Description : Which of the following reagents cannot be used to prepare an alkyl chloride from an alcohol? (a) HCl + ZnCl2 (b) SOCl2 (c) NaCl (d) PCl5
Last Answer : NaCl
Description : Consider the following gaseous equilibrium: PCl3 + Cl2 = PCl5 + heat. Which of the following changes will shift it to the right: w) lower the temperature x) remove some Cl2 y) increase the volume z) add a catalyst
Last Answer : ANSWER: W -- LOWER THE TEMPERATURE
Description : What is the hybridization assumed for phosphorus in PCl5?
Last Answer : ANSWER: d sp3
Description : What happens when a chemical bond is formed? (1) energy is always absorbed (2) energy in always released (3) more energy is released than is absorbed (4) energy is neither released nor ... as potential energy. Upon the breaking of these bonds the energy is released thereby creating usable energy.
Last Answer : Silver nitrate solution is kept in brown bottles in laboratory because - (1) it reacts with ordinary white bottles (2) brown bottles stops the passage of light through it (3) brown bottles do not react with it (4) brown bottles react with it
Description : In an oxygen molecule, two atoms are united by - (1) one bond (2) two bonds (3) three bonds (4) four bonds
Last Answer : (2) two bonds Explanation: Two oxygen atoms can both achieve stable structures by sharing two pairs of electrons as in the diagram. Two electrons of each of the atom in the oxygen molecule ... is shown conventionally by two lines joining the atoms. Each line represents one pair of shared electrons.
Description : Is the bond energy of all the four C-H bonds in CH4 molecule equal? If not then why ? How is C-H bond energy then reported?
Last Answer : Ans. No because after breaking of C-H bonds one by one, the electronic environments change. The reported value is the average of of the bond dissociation energies of the four C-H bonds.
Description : How do double bonds in the rubber molecule influence their structure and reactivity ?
Last Answer : Due to presence of double bond the rubber molecule show cis-configuration because which the polymer chains can not come close to each other and get boiled but as they have their ... Waals intraction between the molecules consequently they get elastic property, solubility in organic solvents etc.
Description : Which of the following statements are correct concerning benzene? (a) Benzene is a planar molecule. (b) The six carbon-carbon bonds have the same length. (c) Benzene has alternating single and double bonds. (d) (a) and (b)
Last Answer : (a) and (b)
Description : Explain why the water molecule has a bent shape and a bond angle less than 109.5° The electron repulsion between the two lone pairs of electrons on the oxygen of water causes the O–H bonds to squeeze close together
Last Answer : The electron repulsion between the two lone pairs of electrons on the oxygen of water causes the O–H bonds to squeeze close together
Description : Which of the following statements correctly describes the general reactivity of alkynes? (a) An alkyne is an electron-rich molecule and therefore reacts as a nucleophile. (b) The σ bonds ... fail to undergo electrophilic addition reactions. (d) Alkynes are generally more reactive than alkenes.
Last Answer : Alkynes are generally more reactive than alkenes.
Description : The angle between any two carbon-hydrogen bonds in a methane molecule is how many degrees?
Last Answer : ANSWER: 109.5 DEGREES
Description : In an oxygen molecule, two atoms are united by (1) one bond (2) two bonds (3) three bonds (4) four bonds
Last Answer : two bonds
Description : What is the name of the compound with the formula PCl5 ?
Last Answer : Phosphorus pentachloride
Description : Phosphatic fertiliser is graded based on its __________ content. (A) P2O3 (B) PCl5 (C) P2O5 (D) H3PO4
Last Answer : (C) P2O5
Description : In the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2, decrease in the pressure of the system will __________ the degree of dissociation of PCl5. (A) Increase (B) Decrease (C) Not alter (D) None of these
Last Answer : (A) Increase
Description : Pick out the wrong statement pertaining to the decomposition of PCl5 represented by, PCl5 ⇌ PCl3 + Cl2.Degree of dissociation of PCl5 will (A) Decrease on addition of Cl2 (B) Increase on addition of ... at constant pressure (C) Decrease on increasing the pressure of the system (D) None of these
Last Answer : (D) None of thes
Description : Ammonia gas can be dried by (A) PCl5 (B) Quick lime (C) CaCl2 (D) Concentrated H2SO4
Last Answer : (B) Quick lime
Description : The substance used as a smoke screen in warfare is (A) C2H2 (B) SiCl4 (C) P2O5 (D) PCl5
Last Answer : Option B
Description : How the change in pressure at equilibrium position effect the following reaction? PCl5 PCl3 + Cl2
Last Answer : According to Le–chatlier’s principle, by increasing pressure the reaction will move toward less number of moles. In the above reaction, by increasing pressure the reaction will move in backward direction.