248 + Interview Questions in P-Block Elements in Chemistry

151.	What is the basicity of pyrophosphoric acid?(a) Monobasic(b) Tribasic(c) Dibasic(d) TetrabasicThis question was addressed to me in unit test.Question is from P-Block Elements in chapter P-Block Elements of Chemistry – Class 12
Answer» Right answer is (c) Dibasic To elaborate: Pyrophosphoric acid, represented chemically as H4P2O5, is an oxoacid of phosphorus. It is dibasic in nature. This is due to the presence of TWO P – OH bonds that are PRESENT in the molecule which help RELEASE two H^+ ions.

Discussion

152.	What is the most acidic of all?(a) NH3(b) NaOH(c) KOH(d) Alkaline KMnO4This question was addressed to me in an online quiz.The doubt is from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12
Answer» The correct choice is (a) NH3 The explanation: In the LISTED options, except ammonia, every other compound is a strong BASE which automatically makes ammonia the most acidic relative to the mentioned compounds. Although it is a weak base, compared to NaOH, KOH and ALKALINE KMnO4 it is the most acidic AMONGST the four options.

Discussion

153.	Which of the following scientists first discovered helium in the solar spectrum during a total solar eclipse?(a) Lord Rayleigh(b) J N Lockyer(c) William Ramsay(d) Antoine LavoisierThe question was asked in an international level competition.I'd like to ask this question from P-Block topic in section P-Block Elements of Chemistry – Class 12
Answer» Correct option is (b) J N Lockyer The best I can explain: J N Lockyer first DISCOVERED helium in the solar SPECTRUM during a TOTAL solar eclipse on 18^th August, 1868. LATER on, in 1895, it was discovered on the planet Earth by a scientist named William RAMSAY.

Discussion

154.	What is the molecular mass of chlorine?(a) 71.0 kg/kmole(b) 35.5 g/kmole(c) 71.0 g/kmole(d) 35.5 kg/moleThe question was asked at a job interview.This interesting question is from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12
Answer» Correct choice is (a) 71.0 kg/kmole Easy explanation: In the periodic table, the atomic MASS of CHLORINE ATOM is 35.5 AMU. Since chlorine exists in diatomic form, the molecular mass = 35.5g/mole X 2 = 71.0 g/mole. On multiplying and DIVIDING by 1000, 71.0 kg/kmole.

Discussion

155.	Xenon fluorides are reactive.(a) True(b) FalseThis question was addressed to me in an internship interview.This key question is from P-Block Elements topic in chapter P-Block Elements of Chemistry – Class 12
Answer» The correct choice is (b) False Easy EXPLANATION: Fluorine is the most electronegative element and is a very powerful oxidising agent. Although generally unreactive, xenon reacts with fluorine and GETS oxidised forming fluorides of the type XEF2, XEF4 and XeF6. These fluorides not reactive.

Discussion

156.	Which of the following is true about interhalogen compounds?(a) They have unpaired electrons(b) They are highly stable(c) They are diamagnetic(d) They are paramagneticI got this question during a job interview.I'd like to ask this question from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12
Answer» The correct choice is (C) They are diamagnetic To explain I would SAY: INTERHALOGEN compounds are diamagnetic in nature. This is because they have BOND pairs and lone pairs. The A-X bond in interhalogen compounds is much weaker than the X-X bond in halogens, except for the F-F bond.

Discussion

157.	What happens in the purifying chamber in contact process?(a) The compounds are washed with nitrogen(b) Dust particles are removed(c) A spray of HCl is used for drying gasses(d) The compounds are heatedThis question was posed to me by my school principal while I was bunking the class.This key question is from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12
Answer» Right choice is (B) DUST particles are removed For explanation I would say: In the purifying unit the dust particles are removed by blowing STEAM and the soluble impurities are removed by WASHING the gases with water. A spray of conc. SULPHURIC acid is used for drying gasses.

Discussion

158.	Which of the following methods is used to form ozone from oxygen?(a) Standard electric discharge(b) Silent electric discharge(c) Thermal decomposition(d) Heating in an atmosphere of excess oxygenThe question was asked in an internship interview.This intriguing question comes from P-Block Elements topic in division P-Block Elements of Chemistry – Class 12
Answer» The CORRECT choice is (b) Silent ELECTRIC discharge To explain I would say: Standard electric discharge produces sparking when ELECTRICITY is passed through the tube. However, silent electric discharge is more appropriate because the CONVERSION of ozone to OXYGEN is endothermic. The yield may be reduced by the heat from sparks.

Discussion

159.	Which of the following metals does not react with hot water to form an oxide?(a) Calcium(b) Magnesium(c) Iron(d) LithiumI have been asked this question by my college professor while I was bunking the class.I'm obligated to ask this question of P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12
Answer» Correct option is (c) IRON Explanation: Iron is relatively unreactive with respect to other METALS mentioned. Iron FORMS iron (III) oxide on heating vigorously. HOWEVER, lithium, magnesium and calcium all form hydroxides and oxides on reaction with hot WATER.

Discussion

160.	What is the structure of phosphine?(a) Trigonal pyramidal(b) Trigonal bi-pyramidal(c) Rhombohedral(d) PyramidalThis question was addressed to me during an online exam.I want to ask this question from P-Block Elements in chapter P-Block Elements of Chemistry – Class 12
Answer» Right option is (a) TRIGONAL pyramidal Easy EXPLANATION: Phosphine has a trigonal pyramidal STRUCTURE with MOLECULAR symmetry. The length of the bond between phosphorous and hydrogen is 1.42 × 10^-10 m and the bond angles are equal and are known to be 93.5°.

Discussion

161.	Which of these gases is released upon treating zinc with diluted and then concentrated nitric acid?(a) Nitrogen dioxide and nitrous oxide(b) Nitric oxide and nitrous oxide(c) Nitrous oxide and nitrogen dioxide(d) Nitrous oxide and nitric oxideThis question was posed to me during an online interview.This interesting question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» The CORRECT answer is (c) Nitrous oxide and nitrogen dioxide To explain: The PRODUCTS released depend on the concentration of NITRIC ACID. In case of zinc metal, diluted nitric acid treatment RELEASE nitrous oxide and concentrated nitric acid causes the release of nitrogen dioxide.

Discussion

162.	What is the most reactive element of group 16?(a) Oxygen(b) Sulphur(c) Tellurium(d) SeleniumI got this question in class test.I need to ask this question from P-Block in division P-Block Elements of Chemistry – Class 12
Answer» Right answer is (a) OXYGEN Easiest explanation: Oxygen is the most reactive element of group 16. It is the second most ELECTRONEGATIVE element in the PERIODIC table (EN=3.5), the first being FLUORINE (EN=4.0), making it more reactive than the other elements of the group.

Discussion

163.	Which of the following oxides of nitrogen is a neurotransmitter?(a) N2O(b) N2O4(c) NO2(d) NOI have been asked this question in unit test.My question is based upon P-Block Elements topic in chapter P-Block Elements of Chemistry – Class 12
Answer» The correct answer is (d) NO For explanation: ALTHOUGH nitric acid (NO) is very reactive and harmful, it occurs in small traces in BIOLOGICAL systems. It acts as a neurotransmitter and helps in controlling BLOOD pressure by RELAXING blood vessels.

Discussion

164.	Which of the following oxide can act as both reducing and oxidising agent?(a) Dinitrogen oxide(b) Nitric oxide(c) Nitrogen dioxide(d) Dinitrogen pentoxideI have been asked this question during an internship interview.I'd like to ask this question from P-Block Elements in portion P-Block Elements of Chemistry – Class 12
Answer» The correct choice is (b) Nitric oxide Explanation: Nitric oxide acts as both an OXIDISING AGENT and a reducing agent WHEREAS all the other oxides of nitrogen act as oxidising agents only. The oxidising NATURE of nitric acid can be OBSERVED in its reaction with hydrogen sulphide while its reducing nature can be observed in its reaction with acidified potassium permanganate.

Discussion

165.	What does dinitrogen oxide on reaction with sodamide produce?(a) Nitrogen gas(b) Nitric acid(c) Nitrogen dioxide(d) Sodium azideThe question was asked by my college director while I was bunking the class.My enquiry is from P-Block Elements topic in division P-Block Elements of Chemistry – Class 12
Answer» RIGHT answer is (b) Nitric acid To elaborate: Dinitrogen oxide (N2O) or NITROGEN(I) oxide, commonly called laughing gas, reacts with liquid sodamide or SODIUM amide (NANH2) at a TEMPERATURE of 473K in order to produce sodium azide (NaN3) and water.

Discussion

166.	Which process is used for large scale manufacturing of sulphuric acid?(a) Haber’s process(b) Ostwald’s process(c) Smith’s process(d) Contact processThe question was asked during an internship interview.This key question is from P-Block Elements in portion P-Block Elements of Chemistry – Class 12
Answer» Right choice is (d) Contact process To explain: These days sulphuric ACID is mostly PREPARED by the Contact process. The acid produced by this method is free from ARSENIC impurities and hence can be safely used for the preparation of EDIBLE products.

Discussion

167.	What is the hybridization of interhalogen compounds of the type XX’5(Square pyramidal)?(a) sp^3d^2(b) sp^2d^2(c) sp^4d^3(d) sp^3d^3This question was addressed to me in an interview for internship.The question is from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12
Answer» The CORRECT option is (a) sp^3d^2 The EXPLANATION is: The structure of all interhalogen compounds of the type XX’5 involves sp^3d^2 hybridization of the central halogen atom X and hence have octahedral (also called SQUARE pyramidal) geometry and with one position occupied by a LONE pair.

Discussion

168.	Which of the following oxoacid sulfur is known not to bear any acid salt?(a) Sulfuric acid(b) Thiosulfuric acid(c) Sulfonic acid(d) Dithionic acidThis question was addressed to me in unit test.My question is taken from P-Block Elements in division P-Block Elements of Chemistry – Class 12
Answer» The correct choice is (d) Dithionic acid Best EXPLANATION: Dithionic acid is formulated as H2S2O6 and is known to possess no acid SALTS i.e. salt formed due to the loss of one HYDROGEN ion. The diprotic salts of dithionic acid is known as dithionates which are MILD oxidizing and reducing agents as WELL.

Discussion

169.	Which of the following is not a property of sulfur dioxide?(a) Colorless(b) Bent molecule(c) Odorless(d) Polar moleculeThis question was addressed to me by my school principal while I was bunking the class.My question is from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12
Answer» Right choice is (c) Odorless To explain I would say: Sulfur dioxide has a very NASTY, pungent and SHARP smell. It is a choking gas, released when sulfur compounds are burned in excess oxygen. It is a colorless gas and bears a BENT shape with polarity DUE to the electronegativity of the oxygen atom. The structural FORMULA is ^–O – S = O.

Discussion

170.	As ozone transitions from solid to liquid to gas, what is the notable color change?(a) Pale blue to violet to deep blue(b) Violet to pale blue to deep blue(c) Deep blue to violet to pale blue(d) Violet to deep blue to pale blueI have been asked this question in semester exam.The above asked question is from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12
Answer» The correct CHOICE is (d) Violet to DEEP blue to pale blue Best explanation: Ozone freezes at -192.2°C. When in solid state, it forms a violet-black STRUCTURE. After melting, the color transitions to deep blue. Finally, as it is everywhere seen in the sky, ozone gas is pale blue.

Discussion

171.	What type of oxides is formed by non-metals?(a) Oxides with pH 7(d) Oxides which are acidicI got this question in class test.My doubt stems from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12
Answer» Right answer is (d) Oxides which are acidic The best explanation: Non-metals FORM acidic oxides because upon DISSOLUTION in water they liberate FREE H^+ ions. Oxides with pH <=7 also include neutral oxides and not acidic only. Oxides with pH > 7 are basic in NATURE. Amphoteric oxides behave both like acid and base.

Discussion

172.	Phosphorus trichloride does not react with Grignard reagents.(a) True(b) FalseThis question was posed to me in final exam.Origin of the question is P-Block Elements in division P-Block Elements of Chemistry – Class 12
Answer» Right answer is (b) False Easiest explanation: PHOSPHORUS trichloride reacts with Grignard REAGENTS to form substituted phosphines. For example, PCl3 reacts with phenylmagnesium chloride to PRODUCE triphenylphosphate and MAGNESIUM chloride. PCl3 + 3C6H5MgCl → P(C6H5)3 + 3MgCl2.

Discussion

173.	What is the hybridization of phosphine?(a) sp^2 hybridized(b) sp^3 hybridized(c) sp hybridized(d) No hybridizationI got this question in an interview for job.This interesting question is from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12
Answer» The correct choice is (d) No hybridization Explanation: The hybridization of phosphine SEEMS like sp^2 but in REALITY the molecule has no hybridization as it forms all bonds using its pure p orbitals. This can be proved from its bong angle DATA which shows that its BOND angles are 93.5°.

Discussion

174.	Which of the following gas is used as Holmes signal?(a) Hydrogen per oxide(b) Nitrogen(c) Acetylene(d) PhosphineThe question was posed to me in semester exam.This is a very interesting question from P-Block Elements in portion P-Block Elements of Chemistry – Class 12
Answer» Right option is (d) Phosphine Easy EXPLANATION: When a MIXTURE of calcium carbide and calcium phosphide placed in a container is made to react with WATER, it produces the GASES phosphine and acetylene. This signal produced due to the burning gases is called HOLMES signal.

Discussion

175.	What is one method of qualitatively analyzing a given salt for presence of ammonia?(a) Solution turns blue litmus red(b) Heating the salt causing decrepitation(c) Using a reagent to obtain dirty brown precipitate(d) Addition of NaOH causing white gelatinous precipitateI had been asked this question in examination.This intriguing question originated from P-Block Elements in portion P-Block Elements of Chemistry – Class 12
Answer» The CORRECT OPTION is (c) Using a reagent to obtain dirty brown precipitate For EXPLANATION I would say: Typically, Nessler’s reagent is used to test for ammonia. Nessler’s reagent is an ALKALINE solution of potassium tetraiodomercurate (II). When it combines with ammonia it gives dirty brown precipitate due to the formation of [OHg2.NH2]I. Another method is to add a strong base and heat the mixture. The gas given off is pungent and turns red LITMUS blue.

Discussion

176.	Beta-black phosphorus is prepared by heating white phosphorus.(a) True(b) FalseThis question was posed to me in homework.I'm obligated to ask this question of P-Block Elements topic in section P-Block Elements of Chemistry – Class 12
Answer» The correct option is (a) True The explanation is: Yes, Beta-black phosphorus is prepared by heating white phosphorus at 473 K under high pressure(4000-12000 atm) in an inert atmosphere. It has LAYERED structure in which each phosphorus atom is covalently BONDED to three NEIGHBOURING phosphorus atoms.

Discussion

177.	What happens when sodium is put in a solution of ammonia?(a) It generates a lot of heat(b) It does not dissolve(c) It produces deep blue color(d) Ammonia liquid evaporates due to heatThe question was asked during an online exam.I would like to ask this question from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12
Answer» The correct choice is (c) It PRODUCES deep blue COLOR For explanation: When SODIUM is introduced to LIQUID ammonia, it separates into sodium ion and a single electron (Na → Na^+ + e^–). The single electron produces the deep blue color due to solvation effect producing e^–[NH3]n.

Discussion

178.	How many bonds does chlorine make with oxygen in perchloric acid?(a) 3 double bonds and a single bond(b) 7 single bonds(c) 2 single bonds and 2 double bonds(d) 3 single bonds and a double bondThis question was addressed to me in examination.I would like to ask this question from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» The correct option is (a) 3 double BONDS and a single bond The explanation: The formula for perchloric acid is HOClO3, in which the chlorine group is attached to 3 oxygen ATOMS and a hydroxyl group. The 3 oxygen atoms are attached to chlorine through a double bond and the hydroxyl group is singly bonded to chlorine. THUS, there are 3 double bonds and a single bond between oxygen and chlorine.

Discussion

179.	Which of the following does not react with hydrochloric acid to give chlorine as a product?(a) KMnO4(b) MnO2(c) K2Cr2O7(d) MgI had been asked this question in an interview for internship.Enquiry is from P-Block Elements in division P-Block Elements of Chemistry – Class 12
Answer» Right choice is (d) Mg To elaborate: CONCENTRATED hydrochloric acid REACTS with strong oxidising agents to YIELD chlorine gas. KMNO4, MnO2, K2Cr2O7, PbO2 are examples of oxidising agents which release chlorine on reaction with hydrochloric acid.

Discussion

180.	What is the bond angle of hypochlorous acid?(a) 108°(b) 108.5°(c) 109°(d) 109.5°This question was addressed to me during an internship interview.This interesting question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» Correct CHOICE is (d) 109.5° To elaborate: Hypochlorous ACID is an oxoacid of chlorine in which the hydrogen atom is SINGLY bonded to the oxygen atom and chlorine is also singly bonded to oxygen atom FORMING a bend structure with BOND angle 109.5°.

Discussion

181.	What is the boiling point of hydrogen chloride?(a) 168 K(b) 189 K(c) 198 K(d) 150 KThis question was posed to me by my school principal while I was bunking the class.I'd like to ask this question from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12
Answer» Correct answer is (b) 189 K To explain: Hydrogen chloride is a colourless and pungent smelling GAS. It can be EASILY liquefied to form a colourless liquid. The boiling point of hydrogen chloride is 189 K and its freezing point is 150 K.

Discussion

182.	Sulphuric acid is called the ‘King of Acids’.(a) True(b) FalseI had been asked this question in homework.My question is taken from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» The correct choice is (a) True The EXPLANATION is: Even though hydrogen iodide is STRONGER sulphuric acid is called the ‘KING of ACIDS’. All acids can be formed from sulphuric acid, because of its low volatility, it can be used to manufacture more volatile acids from their corresponding salts.

Discussion

183.	Hydrogen chloride is manufactured by the ‘salt cake’ method.(a) True(b) FalseThe question was asked during an online exam.The query is from P-Block Elements in division P-Block Elements of Chemistry – Class 12
Answer» CORRECT ANSWER is (a) True To elaborate: Hydrogen chloride is MANUFACTURED by the ‘salt cake’ method. In this method, concentrated sulphuric acid is ADDED to rock salt in ORDER to form sodium sulphate and hydrogen chloride.

Discussion

184.	Which of the following would instantly react with chlorine?(a) Copper(b) Magnesium(c) Iron(d) AluminumThis question was addressed to me during an internship interview.I want to ask this question from P-Block Elements topic in chapter P-Block Elements of Chemistry – Class 12
Answer» The correct option is (B) Magnesium Explanation: Out of the four metals GIVEN, magnesium will readily lose electrons due to its relatively higher REACTIVITY. Copper and IRON are not affected by gaseous or liquid chlorine. Lastly, aluminum forms a tough, passive oxide LAYER which prevents it from reacting with external reagents.

Discussion

185.	What is the electronic configuration of chloride?(a) 1s^22s^22p^63s^23p^5(b) 1s^22s^22p^63s^23p^6(c) 1s^22s^22p^5(d) [Ar]4s^24p^3This question was addressed to me during an online exam.The query is from P-Block Elements in division P-Block Elements of Chemistry – Class 12
Answer» The correct option is (B) 1s^22s^22p^63s^23p^6 To EXPLAIN: Chlorine has the atomic number 17. However, chloride has 18 ELECTRONS. Consequently, it ATTAINS the electronic configuration of argon i.e.1s^22s^22p^63s^23p^6.

Discussion

186.	Before subjecting Mg ribbons to flame, it is rubbed with sandpaper. Why?(a) To increase surface area for combustion(b) To increase roughness of surface(c) To remove oxide layer(d) To remove moistureThis question was posed to me in exam.Question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» Correct option is (c) To REMOVE oxide LAYER The explanation is: In order to ensure effective BURNING of the magnesium ribbon, it is cleaned with sandpaper to remove dust PARTICLES along with the layer of magnesium oxide, which may PREVENT it from burning completely.

Discussion

187.	Which of the following is incorrect about Hypophosphorous acid?(a) It is also called phosphonic acid(b) The oxidation state of phosphorus is +1(c) It is monobasic(d) It is represented by the formula H3PO2The question was posed to me in semester exam.I would like to ask this question from P-Block Elements in portion P-Block Elements of Chemistry – Class 12
Answer» Right option is (a) It is also called phosphonic acid The best I can explain: Hypophosphorous acid, also known as phosphinic acid, is an OXOACID of phosphorus in which, the oxidation STATE of phosphorus is +1. It is MONOBASIC in nature, that is, it dissociates to produce one hydrogen ion. It is represented by the formula H3PO2.

Discussion

188.	Which of the following is not formed on hydrolysis of PCl5?(a) POCl3(b) H3PO4(c) HCl(d) PCl3I got this question in an interview.The question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» Correct answer is (d) PCl3 The best explanation: In moist air, phosphorus PENTACHLORIDE undergoes hydrolysis to first FORM POCL3 and then FINALLY phosphoric acid. PCl3 + H2O → POCl3 + 2HCl POCl3 + 3H2O → H3PO4 + 3HCl However, with excess of water, PCl5 reacts violently to form H3PO4 and HCl. PCl5 + 4H2O (excess) → H3PO4 + 5HCl.

Discussion

189.	Which of the following is most stable?(a) AsCl5(b) SbCl5(c) PCl5(d) BiCl5The question was asked in my homework.The question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» The correct option is (c) PCL5 For explanation: Phosphorus pentachloride is the most stable. As we MOVE down a group in the periodic table, the stability of the pentahalides decreases due to inert pair EFFECT. So, the correct order of stability is PCl5 > SbCl5 > AsCl5 > BiCl5.

Discussion

190.	What is the catalyst used in the industrial manufacture of nitric acid?(a) Powdered iron (III) oxide(b) Vanadium (V) oxide(c) Zinc-mercury amalgam(d) Platinum-Rhodium gauze sheetThe question was posed to me during an interview for a job.I need to ask this question from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12
Answer» The CORRECT option is (d) Platinum-Rhodium GAUZE sheet For explanation I would say: Pt-Rh gauze sheet is widely used as the catalyst in ammonic oxidation, the first STEP of Ostwald’s PROCESS. Fe2O3 is used in Haber’s process; V2O5 in contact process and Zn (HG) is used in Clemmensen reduction of aldehydes.

Discussion

191.	Which of the following is not an alternative name of dinitrogen trioxide?(a) Nitrogen sesquioxide(b) Nitrogen (III) oxide(c) Anhydride of nitrous acid(d) Nitrogen peroxideI had been asked this question in semester exam.Asked question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» Right choice is (d) Nitrogen peroxide Best explanation: Dinitrogen TRIOXIDE is an oxide of nitrogen which can also be called as nitrogen sesquioxide, nitrogen (III) oxide or ANHYDRIDE of nitrous ACID. Nitrogen dioxide is also known as nitrogen peroxide.

Discussion

192.	Why does fluorine form only one oxoacid?(a) High electronegativity of fluorine(b) Large radius of fluorine(c) Presence of a single valence electron(d) High electropositivity of fluorineI have been asked this question in an internship interview.This is a very interesting question from P-Block Elements in division P-Block Elements of Chemistry – Class 12
Answer» RIGHT option is (a) High electronegativity of fluorine Easiest explanation: Fluorine is the most electronegative ELEMENT on the periodic table. Due to its high electronegativity and SMALL atomic RADIUS, fluorine only forms one oxoacid, HOF known as HYPOFLUOROUS acid.

Discussion

193.	Which of the following scientists first prepared hydrogen chloride by heating common salt with sulphuric acid?(a) Rudolf Glauber(b) Joseph Priestley(c) Humphry Davy(d) Antoine LavoisierI had been asked this question by my school principal while I was bunking the class.The query is from P-Block Elements topic in division P-Block Elements of Chemistry – Class 12
Answer» The correct answer is (a) RUDOLF Glauber Explanation: Rudolf Glauber prepared hydrogen CHLORIDE in 1648 by HEATING common salt with CONCENTRATED sulphuric acid. Humphry Davy, in 1810, established its true nature and showed that it is a COMPOUND of hydrogen and chlorine.

Discussion

194.	Which of the following halogen exists as a solid at room temperature?(a) Chlorine(b) Fluorine(c) Iodine(d) BromineThe question was asked in examination.My enquiry is from P-Block topic in chapter P-Block Elements of Chemistry – Class 12
Answer» Correct answer is (b) Fluorine To explain: The strength of the van der Waals between MOLECULES forces increases as the size of the HALOGEN increases from fluorine to iodine. As a result, F2 and Cl2 are GASES at room temperature, Br2 is a liquid whereas I2 is a SOLID.

Discussion

195.	What is the acidity of peroxodisulfuric acid?(a) 1(b) 3(c) 4(d) Does not existThe question was posed to me in homework.Asked question is from P-Block Elements topic in division P-Block Elements of Chemistry – Class 12
Answer» Correct option is (d) Does not exist For EXPLANATION: Acids do not BEAR acidity. The number of hydrogen ions released by an ACID is referred to as its basicity. The FORMULA of peroxodisulfuric acid is H2S2O8 and can RELEASE 2 H^+ ions, hence the acidity is 2.

Discussion

196.	What is the primary product when carbon is treated with concentrated sulfuric acid?(a) Carbon dioxide(b) Carbon monoxide(c) Carbon sulfate(d) Carbon sulfideThe question was asked during a job interview.This intriguing question originated from P-Block Elements topic in chapter P-Block Elements of Chemistry – Class 12
Answer» CORRECT option is (a) Carbon dioxide Easy explanation: Since SULFURIC acid is a very strong OXIDANT, it oxidizes carbon to carbon dioxide. With EXCESS of oxygen available from sulfuric acid and water, carbon monoxide is rarely formed. Carbon sulfate does not exist and carbon SULFIDE formed as a reaction between carbon and sulfur.

Discussion

197.	What is the nature of zinc oxide?(a) Acidic(b) Amphoteric(c) Basic(d) UndeterminedI have been asked this question by my school principal while I was bunking the class.My doubt is from P-Block Elements in chapter P-Block Elements of Chemistry – Class 12
Answer» The correct option is (b) AMPHOTERIC The explanation: Amphoteric oxides are those oxides which can act both as an acid as well as BASE. Factually it is DETERMINED that zinc, ALUMINUM and tin oxides are amphoteric in nature.

Discussion

198.	How many P-H bonds does hypophosphorous acid contain?(a) 1(b) 2(c) 3(d) 4The question was posed to me by my school principal while I was bunking the class.My enquiry is from P-Block Elements topic in division P-Block Elements of Chemistry – Class 12
Answer» Correct choice is (b) 2 Best explanation: Hypophosphorous ACID, ALSO called as phosphinic acid, has one P – OH bond, 2 P – H BONDS and one P = O bond. It is monobasic in nature due to the presence of the one P – OH bond.

Discussion

199.	Orthophosphorous acid can be made from phosphorous trioxide.(a) True(b) FalseThe question was posed to me by my school principal while I was bunking the class.Asked question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12
Answer» Correct option is (a) True Explanation: Orthophosphorous ACID, also known as phosphonic acid, is an OXOACID of phosphorus. It can be PREPARED by ADDING phosphorus trioxide (P4O6) to water (H2O) in the ratio 1:6 resulting in the formation of 4 molecules of phosphonic acid.

Discussion

200.	What is the reaction involved in Holmes signal?(a) Ca3P2 + 6H2O → 2PH3 + 3Ca(OH) 2(b) Ca3P2 + 6H2O → 2PH3 → P2H4 + P4O6 and CaC2 + H2O → C2H2(c) Ca3P2 + 6HCl → 2PH3 + 3CaCl2(d) P4 + 3NaOH + 3H2O → PH3 + 3NaH2PO2I got this question in exam.This key question is from P-Block Elements in portion P-Block Elements of Chemistry – Class 12
Answer» Right option is (b) CA3P2 + 6H2O → 2PH3 → P2H4 + P4O6 and CaC2 + H2O → C2H2 Easiest explanation: The REACTIONS involved in Holmes signal are: Ca3P2 + 6H2O → 2PH3 → P2H4 + P4O6 and CaC2 + H2O → C2H2 Calcium CARBIDE and calcium phosphide both react with water to give acetylene and phosphine respectively. These gases burn to give the signal.

Discussion

Explore topic-wise InterviewSolutions in .

What is the basicity of pyrophosphoric acid?(a) Monobasic(b) Tribasic(c) Dibasic(d) TetrabasicThis question was addressed to me in unit test.Question is from P-Block Elements in chapter P-Block Elements of Chemistry – Class 12

What is the most acidic of all?(a) NH3(b) NaOH(c) KOH(d) Alkaline KMnO4This question was addressed to me in an online quiz.The doubt is from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12

What is the molecular mass of chlorine?(a) 71.0 kg/kmole(b) 35.5 g/kmole(c) 71.0 g/kmole(d) 35.5 kg/moleThe question was asked at a job interview.This interesting question is from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12

Xenon fluorides are reactive.(a) True(b) FalseThis question was addressed to me in an internship interview.This key question is from P-Block Elements topic in chapter P-Block Elements of Chemistry – Class 12

What is the structure of phosphine?(a) Trigonal pyramidal(b) Trigonal bi-pyramidal(c) Rhombohedral(d) PyramidalThis question was addressed to me during an online exam.I want to ask this question from P-Block Elements in chapter P-Block Elements of Chemistry – Class 12

What is the most reactive element of group 16?(a) Oxygen(b) Sulphur(c) Tellurium(d) SeleniumI got this question in class test.I need to ask this question from P-Block in division P-Block Elements of Chemistry – Class 12

Which of the following oxides of nitrogen is a neurotransmitter?(a) N2O(b) N2O4(c) NO2(d) NOI have been asked this question in unit test.My question is based upon P-Block Elements topic in chapter P-Block Elements of Chemistry – Class 12

What is the hybridization of interhalogen compounds of the type XX’5(Square pyramidal)?(a) sp^3d^2(b) sp^2d^2(c) sp^4d^3(d) sp^3d^3This question was addressed to me in an interview for internship.The question is from P-Block Elements topic in section P-Block Elements of Chemistry – Class 12

Which of the following oxoacid sulfur is known not to bear any acid salt?(a) Sulfuric acid(b) Thiosulfuric acid(c) Sulfonic acid(d) Dithionic acidThis question was addressed to me in unit test.My question is taken from P-Block Elements in division P-Block Elements of Chemistry – Class 12

What type of oxides is formed by non-metals?(a) Oxides with pH 7(d) Oxides which are acidicI got this question in class test.My doubt stems from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12

Phosphorus trichloride does not react with Grignard reagents.(a) True(b) FalseThis question was posed to me in final exam.Origin of the question is P-Block Elements in division P-Block Elements of Chemistry – Class 12

What is the hybridization of phosphine?(a) sp^2 hybridized(b) sp^3 hybridized(c) sp hybridized(d) No hybridizationI got this question in an interview for job.This interesting question is from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12

Which of the following gas is used as Holmes signal?(a) Hydrogen per oxide(b) Nitrogen(c) Acetylene(d) PhosphineThe question was posed to me in semester exam.This is a very interesting question from P-Block Elements in portion P-Block Elements of Chemistry – Class 12

Beta-black phosphorus is prepared by heating white phosphorus.(a) True(b) FalseThis question was posed to me in homework.I'm obligated to ask this question of P-Block Elements topic in section P-Block Elements of Chemistry – Class 12

Which of the following does not react with hydrochloric acid to give chlorine as a product?(a) KMnO4(b) MnO2(c) K2Cr2O7(d) MgI had been asked this question in an interview for internship.Enquiry is from P-Block Elements in division P-Block Elements of Chemistry – Class 12

What is the bond angle of hypochlorous acid?(a) 108°(b) 108.5°(c) 109°(d) 109.5°This question was addressed to me during an internship interview.This interesting question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12

What is the boiling point of hydrogen chloride?(a) 168 K(b) 189 K(c) 198 K(d) 150 KThis question was posed to me by my school principal while I was bunking the class.I'd like to ask this question from P-Block Elements topic in portion P-Block Elements of Chemistry – Class 12

Sulphuric acid is called the ‘King of Acids’.(a) True(b) FalseI had been asked this question in homework.My question is taken from P-Block Elements in section P-Block Elements of Chemistry – Class 12

Hydrogen chloride is manufactured by the ‘salt cake’ method.(a) True(b) FalseThe question was asked during an online exam.The query is from P-Block Elements in division P-Block Elements of Chemistry – Class 12

Which of the following would instantly react with chlorine?(a) Copper(b) Magnesium(c) Iron(d) AluminumThis question was addressed to me during an internship interview.I want to ask this question from P-Block Elements topic in chapter P-Block Elements of Chemistry – Class 12

What is the electronic configuration of chloride?(a) 1s^22s^22p^63s^23p^5(b) 1s^22s^22p^63s^23p^6(c) 1s^22s^22p^5(d) [Ar]4s^24p^3This question was addressed to me during an online exam.The query is from P-Block Elements in division P-Block Elements of Chemistry – Class 12

Which of the following is not formed on hydrolysis of PCl5?(a) POCl3(b) H3PO4(c) HCl(d) PCl3I got this question in an interview.The question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12

Which of the following is most stable?(a) AsCl5(b) SbCl5(c) PCl5(d) BiCl5The question was asked in my homework.The question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12

Which of the following halogen exists as a solid at room temperature?(a) Chlorine(b) Fluorine(c) Iodine(d) BromineThe question was asked in examination.My enquiry is from P-Block topic in chapter P-Block Elements of Chemistry – Class 12

What is the acidity of peroxodisulfuric acid?(a) 1(b) 3(c) 4(d) Does not existThe question was posed to me in homework.Asked question is from P-Block Elements topic in division P-Block Elements of Chemistry – Class 12

What is the nature of zinc oxide?(a) Acidic(b) Amphoteric(c) Basic(d) UndeterminedI have been asked this question by my school principal while I was bunking the class.My doubt is from P-Block Elements in chapter P-Block Elements of Chemistry – Class 12

How many P-H bonds does hypophosphorous acid contain?(a) 1(b) 2(c) 3(d) 4The question was posed to me by my school principal while I was bunking the class.My enquiry is from P-Block Elements topic in division P-Block Elements of Chemistry – Class 12

Orthophosphorous acid can be made from phosphorous trioxide.(a) True(b) FalseThe question was posed to me by my school principal while I was bunking the class.Asked question is from P-Block Elements in section P-Block Elements of Chemistry – Class 12