Description : Pick out the wrong statement. (A) Low intensity explosives are also called propellants, whereas high intensity explosive are called detonators (B) Gun powder comprises of 75% salt petre, 15% charcoal ... TNT is a hygroscopic explosive having very high melting point and is non-toxic to human being
Last Answer : (D) TNT is a hygroscopic explosive having very high melting point and is non-toxic to human being
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 : What type of bond is SiF4?
Last Answer : The bonds are covalent.
Description : Prussian blue is chemically represented by (A) FeO.TiO2 (B) Ca SO4 . 2H2O (C) Fe4 [Fe (CN6 )3 ] (D) AlF3 . 3NaF
Last Answer : (C) Fe4 [Fe (CN6 )3 ]
Description : The energy required to melt one mole of a solid at its melting point is called one of the following. w) the molar heat of fusion x) the molar hear of vaporization y) the molar heat of capacity z) the melting point
Last Answer : ANSWER: W -- THE MOLAR HEAT OF FUSION
Description : Reaction between X and Y forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z? A) Has high melting point B) Has low melting point C) Conducts electricity in molten state D) Occurs as solid
Last Answer : B) Has low melting point
Description : Explain why o-hydroxybenzaldehyde is a liquid at room temperature while p-hydroxybenzaldehyde is a high melting solid.
Last Answer : Due to interamolecular H-bonding ortho-hydroxy benzaldehyde exists as discrete molecule whereas due to intermolecular H-bonding, p-hydroxybenzaldehyde exists as associated molecules. To break these intermolecular ... a liquid at room temperature while p-hydroxy benzaldehyde is a high melting solid.
Description : What kind of solid tends to to have the lowest melting point?
Last Answer : Ones made of molecules
Description : If a substance is a solid at 0 degrees celcius can it have a melting point at 45 degrees celcius?
Last Answer : What is the answer ?
Description : Physical change of a solid to a liquid at the melting point?
Last Answer : This is the transformation of a solid in a liquid (melting).
Description : An unknown element is a soft metallic solid. It is highly reactive and has a low melting point. In which group of the periodic table is it most likely to be found?
Last Answer : Sodium - group 1
Description : The point at which the solid, liquid and gaseous forms of a substance co-exist is called its (a) boiling point (b) melting point (c) triple point (d) freezing point
Last Answer : Ans:(c)
Description : The point at which the solid, liquid and gaseous forms of a substance co-exist is called its (a) Boiling point (b) Melting point (c) Triple point (d) Freezing point
Description : Solid and liquid phases of a substance are in equilibrium at the (A) Critical temperature (B) Melting point (C) Freezing point (D) Both (B) and (C)
Last Answer : D) Both (B) and (C)
Description : Which of the following properties of a solid is not dependent on crystal imperfection? (A) Ductility (B) Semi-conductivity (C) Melting point (D) Yield stress
Last Answer : (C) Melting point
Description : What is the amount of heat needed to turn 1 kg of the substance at its melting point from the solid to liquid state? A. Heat of fusion B. Heat of vaporation C. Heat of condensation D. Heat of fission
Last Answer : Heat of fusion
Description : Which of the following is not property of sodium metal? a) lustre b)hard c)low melting point d)solid at room temperature.
Last Answer : c)low melting point
Description : (a) What happens when a Ferromagnetic or Ferrimagnetic solid is heated ? (b) The ions of MgO and NaF all have the same number of electrons and intermolecular distance are about the same (235 & 215 pm). Why are the melting points are so different (2642 °C & 992 °C ?
Last Answer : (a) It changes into paramagnetic at hight temperature due to randomization of spins. (b) The ions in MgO carry two unit charges. In NaCl only one unit charge. Hence electrostatic forces of attraction in MgO are stronger.
Description : Ceramic nuclear metals compared to solid nuclear metals have (A) Higher melting points (B) Low strength at high temperature (C) More chances of radiation damage (D) Poorer corrosion resistance
Last Answer : (A) Higher melting points
Description : Which noble gas has the highest melting point ? w) argon x) krypton y) xenon z) radon
Last Answer : ANSWER: Z -- RADON
Description : Metals have ______. (1) High melting and boiling point (2) Low melting and boiling point (3) High melting and low boiling point (4) Low melting and high boiling point
Last Answer : (1) High melting and boiling point
Description : In arc welding, Argon is used because of its - (1) Low reactivity with metal (2) Ability to lower the melting point of the metal (3) High flammability (4) High calorific value
Last Answer : (1) Low reactivity with metal Explanation: In arc welding, Argon is used as a shielding gas because it is chemically inert and forms no compounds. At the high temperatures that welding requires, the ... to brittle welds and instability in the welding arc. So,argon and other inert gases are sprayed.
Description : Although Diamond is Covalent, yet it has high melting point. Why?
Last Answer : Ans. All the four valencies are satisfied by carbon.
Description : Amino acids have relatively high melting point as compared to corresponding haloacids. Explain.
Last Answer : Ans: Amino acids have relatively higher m.p as compared to corresponding haloacids. We know that amino acids have amino (basic) group and carboxylic (acid) group. A proton which comes from ... form amino acids become crystalline solids and due to this salt like structure show higher melting point.
Description : A zwitterion has which of the following properties (a) no net charge (b) a high melting point (c) soluble in water (d) all of these
Last Answer : all of these
Description : Diamond has each of the following properties except: w) extreme hardness x) ability to conduct electricity y) high melting point z) tendency to burn in air
Last Answer : ANSWER: X -- ABILITY TO CONDUCT ELECTRICITY
Description : In arc welding, Argon is used because of its (1) Low reactivity with metal (2) Ability to lower the melting point of the metal (3) High flammability (4) High calorific value
Last Answer : Low reactivity with metal
Description : Which of the following is not Powder-Based RP system? a.Selective Laser Sintering (SLS) b.Solid Object Ultraviolet-Laser Printer (SOUP) c.Electron Beam Melting (EBM) d.Direct Metal Deposition (DMD)
Last Answer : b.Solid Object Ultraviolet-Laser Printer (SOUP)
Description : Which of the following is not Solid-based RP system? a.Laminated Object Manufacturing (LOM) b.Paper Lamination Technology (PLT) c.Electron Beam Melting (EBM) d.Fused Deposition Modeling (FDM)
Last Answer : c.Electron Beam Melting (EBM)
Description : What kind of solid tends to have the solid lowest melting points?
Last Answer : Solids made up of molecules
Description : Melting temperature of DNA is the temperature at which (A) Solid DNA becomes liquid (B) Liquid DNA evaporates (C) DNA changes from double helix into supercoiled DNA (D) Native double helical DNA is denatured
Last Answer : Answer : D
Description : Which method, vapor phase oxidation or direct-melt process, transforms deposited material into a solid glass preform by heating the porous material without melting?
Last Answer : Vapor phase oxidation.
Description : What term refers to the heat needed to change a unit mass of a substance at its melting temperature from a solid into a liquid?
Last Answer : ANSWER: HEAT OF FUSION or LATENT HEAT OF FUSION or ENTHALPY OF FUSION
Description : Maximum combustion temperature in gas turbines is of the order of 1100 to 10°C whereas same is around 00°C in I.C. engine ? Why ?
Last Answer : High temperature in I.C. engine can be tolerated because it lasts for a fraction of second but gas turbines have to face it continuously which metals can’t withstand.
Description : Pick out the correct statement. (A) A real gas on expansion in vacuum gets heated up (B) An ideal gas on expansion in vacuum gets cooled (C) An ideal gas on expansion in vacuum gets heated up (D) A real gas on expansion in vacuum cools down whereas ideal gas remains unaffected
Last Answer : (D) A real gas on expansion in vacuum cools down whereas ideal gas remains unaffecte
Description : Why is it advisable not to draw current for many appliances from a single point? (a) Current will decrease (b) Current will increase (c) Current and voltage both will increase (d) Voltage will decrease whereas current will increase
Last Answer : Ans:(d)
Description : The R.L. of ground water table on the sides of a valley is 1505 m whereas R.L. of the stream water is 1475 m. If 60° slope consists of pervious soil between R.L. 1485 m to 1500 m, the gravity spring may ... of reduced level (A) 1500 m (B) 1505 m (C) 1475 m (D) 1485 m
Last Answer : (D) 1485 m
Description : Which of the following statements are true? A. Contribution doesn’t include fixed cost whereas profit includes fixed cost. B. Contribution is not based on the concept of marginal cost. C. Contribution above breakeven point becomes profit. D. All of the above
Last Answer : C. Contribution above breakeven point becomes profit.
Description : Explain why [Co(NH3)6]3+ is an inner orbital complex whereas [Ni(NH3)6]2+ is an outer orbital complex. (At. no. Co = 27, Ni = 28) -Chemistry
Last Answer : In [Co(NH3)6]3+, the d-electrons of Co3+ ([Ar]3d6 45°) get paired leaving behind two empty d-orbital and undergo d2sp3 hybridization and hence inner orbital complex, while in [Ni(NH3)6]2+ ... of Ni2+([Ar]3d8 45°) do not pair up and use outer 4d subshell hence outer orbital complex.
Description : [Fe(H2O)6]3+ is strongly paramagnetic whereas [Fe(CN)6]3- is weakly paramagnetic. Explain. (At. no. Fe = 26) -Chemistry
Last Answer : In both the cases, Fe is in oxidation state +3. Outer electronic configuration of Fe+3 is : In the presence of CN-, the 3d electrons pair up leaving only one unpaired electron. The ... sp3d2 forming an outer orbital complex. As it contains five unpaired electrons so it is strongly paramagnetic. .
Description : Why Li2CO3 decomposes at a lower temperature whereas Na2CO3 at higher temperature ?
Last Answer : Ans.Li2CO3 is a salt of a weak acid (CO2) and a weak base (LiOH). Since the weak base cannot attract CO2 Strongly, therefore, Li2CO3 decomposes at a lower temperature.On the other hand ,NaOH is a Much stronger base than LiOH and hence can attract CO2 more strongly.
Description : The increasing order of reactivity among group 1 elements is Li
Last Answer : Ans. In group 1 elements (alkali metals) the reactivity of the metals is mainly due to the electron releasing tendency of their atoms, which is related to ionization enthalpy, Since ... electron gain enthalpy. Since both of them decrease down the group, the reactivity therefore decreases.
Description : Why physical adsorption is multimolecular whereas chemisorption is unimolecular ?
Last Answer : Chemisorption takes place as a result of reaction between adsorbent and adsorbate. When the surface of the adsorbent is covered with one layer, no further reaction can take place. Physical adsorption is ... any number of layers may be formed one over the other on the surface of the adsorbent.
Description : Why ammonia solution is used for the cure of honey bee sting, whereas vinegar is used for curing sting of wasp?
Last Answer : Ans: Honey bee sting is acidic so to neutralize its effect we use a basic ammonia solution. Whereas sting of wasp is alkaline so we use vinegar( weak acid) for cure.
Description : C and Si both have same lattice structure, having 4 bonding electrons in each. However, C is insulator where as Si is intrinsic semiconductor. This is because (1) The four bonding electrons in the case of C ... the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Last Answer : (4) The four bonding electrons in the case of C lie in the second orbit, whereas in the case of Si they lie in the third
Description : Which one of the following in not a property of cancerous cells whereas the remaining three are ? (1) They show contact inhibition (2) They compete with normal cells for vital nutrients (3) They do not remain confined in the area of formation (4) They divide in an uncontrolled manner
Last Answer : They show contact inhibition
Description : What is the melting point of titanium ?
Last Answer : Titanium has a melting point of 1677 degrees Celsius.
Description : What is the melting point of scandium ?
Last Answer : Scandium has a melting point of 1541 degrees Celsius.
Description : What is the melting point of helium ?
Last Answer : The melting point of helium is minus 272 degrees Celsius.
Description : What is the melting point of hydrogen ?
Last Answer : The melting point of hydrogen is minus 259 degrees Celsius.