Description : The melting and boiling points of ionic solids are (a) High (b) Low (c) Very low (d) Of intermediate range
Last Answer : Ans:(a)
Description : Which of the following is not a characteristic of organic compounds? (a) They usually have low melting points. (b) They usually are only slightly soluble or insoluble in water. (c) If water ... they seldom conduct an electric current. (d) Bonds which bind the atoms together are nearly always ionic.
Last Answer : Bonds which bind the atoms together are nearly always ionic.
Description : Ionic compounds have high melting and boiling points because A) less energy is required to break the strong interionic attraction B) large amount of energy is required to break the interionic attraction C) No energy is required D) None of the above
Last Answer : B) large amount of energy is required to break the interionic attraction
Description : Most covalent compounds (a) Behave like electrolytes in the molten state (b) Have high melting and boiling points (c) Are hard substances because of strong covalent bonds (d) Are more soluble in non-polar solvents than in polar solvents
Last Answer : Ans:(d)
Description : How compared with the melting points of ionic compounds the melting points of molecular solids tend to be?
Last Answer : Ionic compounds have a higher melting point.
Description : Define intermolecular forces. Also write down effect of intermolecular forces on melting points & boiling points of substances?
Last Answer : The forces of attraction present between the molecules of a compound are called Intermolecular forces''. Effect of intermolecular forces on the m.p and b.p of substances If intermolecular forces of attractions in ... . And if these forces are weak then the m.p and b.p will be relatively lower.
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 : Pick out the wrong statement pertaining to the properties of glasses. Glasses generally have (A) High electrical insulation properties (B) Sharp melting points (C) Low co-efficient of thermal expansion (D) Compressive strength much greater than their tensile strengths
Last Answer : (B) Sharp melting points
Description : Change in volume of metals from absolute zero temperature to their melting points is (A) Almost same for all metals (B) Different for different metals (C) Less for low melting point metals (D) Less for high melting point metals
Last Answer : (A) Almost same for all metals
Description : Arsenic sulphide forms a sol with a negative charge. Which of the following ionic substances should be most effective in coagulating the sol?
Last Answer : Arsenic sulphide forms a sol with a negative charge. Which of the following ionic substances should be most effective in ... )_(3)` D. `Na_(3)PO_(4)`
Description : What are five physical properties of ionic substances?
Last Answer : Five physical properties of ionic substances: density, hardness, melting point, boiling point, thermal conductivity.
Description : Some substances are good conductor of electricity in both the solid and liquid states. These substances are generally-------? A. ionic substances B. metallic substances (Answer) C. molecular solids D. covalent network solids
Last Answer : B. metallic substances (Answer)
Description : Ionic substances dissolve in water to form: w) highly acid solutions x) electrolytic solutions y) colloids z) emulsions
Last Answer : ANSWER: X -- ELECTROLYTIC SOLUTIONS
Description : Which of the following substances is an ionic netw solid? w) Diamond x) Table Salt y) Brass z) Dry ice
Last Answer : ANSWER: X -- TABLE SALT
Description : Why do covalent compounds have low melting points?
Last Answer : Because although the covalent bonds between the elements are strong, there are only weak forces between the molecules so they have low melting points
Description : Carbon compounds have usually low melting points and
Last Answer : boiling points.
Description : The metals with very low melting points which melts by the temperature of palm are A) Sodium and potassium B) Lead and magnesium C) Aluminium and zinc D) Gallium and caesium
Last Answer : D) Gallium and caesium
Description : Which of the following statements is not true about triacylglycerols? (a) When solids and semisolids at room temperature, they are called fats. (b) When liquids at room temperature, they are ... low melting points are composed of saturated fatty acids, causing them to be liquids at room temperature
Last Answer : Triacylglycerols with low melting points are composed of saturated fatty acids, causing them to be liquids at room temperature
Description : Hot dipping process is used for coating a low melting point metal (e.g. Pb, Sn, Zn) on iron, steel & copper having relatively higher melting points. Which of the following is not a hot dipping process? (A) Galvanising (B) Tinning (C) Sherardizing (D) None of these
Last Answer : (C) Sherardizing
Description : Choose the incorrect statement pertaining to organic compounds (1) They have low melting and boiling points (2) They do not dissolve in water (3) They are not easily combustible (4) They contain mainly carbon and hydrogen
Last Answer : They are not easily combustible
Description : Which one of the following substances does not have a melting point? (1) Bromine (2) Sodium chloride (3) Mercury (4) Glass
Last Answer : (3) Mercury Explanation: The boiling point is the temperature at which a material changes from a liquid to a gas (boils) while the melting point is the temperature at which a material changes from a solid to a liquid (melts).
Description : Pick out the correct statement. (A) Like internal energy and enthalpy, the absolute value of standard entropy for elementary substances is zero (B) Melting of ice involves increase in enthalpy and ... of an ideal gas depends only on its pressure (D) Maximum work is done under reversible conditions
Last Answer : (D) Maximum work is done under reversible conditions
Description : Which of the following substances would be expecte to have the highest melting point? w) Potassium Bromide x) Iodine y) Methane z) Hydrogen Chloride
Last Answer : ANSWER: W -- POTASSIUM BROMIDE
Description : Why do alcohols have boiling points much higher than hydrocarbons of similar molecular weight? (a) Alcohols have greater van der Waals attraction forces. (b) Alcohol molecules have greater ... of volatilization. (d) Alcohols must overcome greater ionic forces in the process of volatilization.
Last Answer : Hydrogen bonds must be broken in the process of volatilization
Description : What are melting points and boiling points ? What is melting point and boiling point ?
Last Answer : Melting point refers to the process of melting a solid into a liquid at a certain temperature. Boiling point is the temperature at which a liquid evaporates. Therefore , the temperature at which a liquid begins to evaporate is called the 'boiling point' of that substance.
Description : The points noted by arrows are melting and boiling points of the metal zinc and magnasium. `Delta G^(0)` as a function of temperature for some reactio
Last Answer : The points noted by arrows are melting and boiling points of the metal zinc and magnasium. `Delta G^(0)` ... +Zn rarr Mg+ZnO` D. `ZnO+Mg rarrZn+MgO`
Last Answer : The points noted by arrows are melting and boiling points of the metal zinc and magnasium. `Delta G^(0)` as a ... gt 500^(@)C " but " lt 1000^(@)C`
Last Answer : The points noted by arrows are melting and boiling points of the metal zinc and magnasium. `Delta G^(0)` as a ... C. `500^(@)C` D. `1200^(@)C`
Description : What kind of solid tends to have the solid lowest melting points?
Last Answer : Solids made up of molecules
Description : If a substance forms crystals when it solidifies its melting and freezing points are the same?
Last Answer : Melting and freezing points are identical.
Description : How could you use a difference in melting points (freezing points) to separate a solution of two liquids?
Last Answer : freeze one liquid while the other one is still liquidized.
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 : Give reasons : (a) Diamond and rhombic Sulphur are covalent solids, but the latter has lower melting points. (b) Among NaCl and CsCl, CsCl is quite stable.
Last Answer : (a) Due to weak Vander Waal’s Force in Sulphur molecule. (b) CsCl coordination number is 8. It is surrounded by 8 anion tightly.
Description : Which of the following best explains why the melting points of saturated fats increase with increasing molecular weight? (a) decreased hydrogen bonding (b) increased hydrogen bonding (c) decreased intermolecular van der Waal’s interactions (d) increased intermolecular van der Waal’s interactions
Last Answer : increased intermolecular van der Waal’s interactions
Description : Fats differ from waxes in that fats have : (a) More unsaturation (b) Higher melting points (c) A glycerol backbone (d) Longer fatty acids
Last Answer : A glycerol backbone
Description : When carboxylic acids and dicarboxylic acids have similar molecular weights, how do their melting points compare? (a) Carboxylic acids have greater melting points. (b) Dicarboxylic acids have greater melting points. (c) Both acids have similar melting points. (d) No consistent trend exists
Last Answer : Dicarboxylic acids have greater melting points
Description : The melting points of aldehydes and ketones tend to : (a) decrease with increasing molecular weight. (b) increase with increasing molecular weight. (c) remain unchanged with increasing molecular weight. (d) be unpredictable due to resonance
Last Answer : increase with increasing molecular weight.
Description : How do the melting points of trans isomers compare to the cis isomers for alkenes? (a) cis isomers have higher melting points (b) trans isomers have higher melting points (c) both have similar melting points (d) no consistent trend is observed
Last Answer : trans isomers have higher melting points
Description : Which statements about alkenes and alkanes of corresponding chain lengths is true? (I) Alkenes have slightly lower melting points than alkanes (II) Alkenes have slightly higher melting points than alkanes (III) Alkenes have higher boiling ... (a) I and III (b) II and IV (c) I and IV (d) II and III
Last Answer : I and III
Description : How does the melting point of propane and ethane compare? (a) the melting point of propane is greater. (b) the melting point of ethane is greater. (c) the melting points are within 5°C of one another. (d) no relationship exists among these alkanes and their melting point
Last Answer : the melting point of ethane is greater.
Description : Agar is used for solidifying culture media because A-it does not affect by the growth of bacteria B-it does not add to the nutritive properties of the medium C-the melting and solidifying points of agar solution are not the same D-all of the above
Last Answer : all of the above
Description : Melting point & boiling points of liquid oxygen are respectively - 218.8°C & - 183°C, while the same for liquid nitrogen is - 210°C & - 195.8°C respectively. The difference in melting points of liquid oxygen & liquid nitrogen is not equal to 8.8 (A) °C (B) °F (C) °K (D) °R
Last Answer : (B) °F
Description : Brazing filler metal used for joining steel plates (A) Melts below the melting points of base metals (B) Melts below 300°C (C) Is copper phosphorous alloy
Last Answer : (A) Melts below the melting points of base metals
Description : The sequence of refractory materials according to increasing melting points is: (A) Dolomite, Magnesia, Bauxite, Chromites (B) Bauxite, Chromites, Dolomite, Magnesia (C) Magnesia, Bauxite, Dolomite, Chromites (D) None of these
Last Answer : Answer: Option B
Description : Is phosphorus high or low melting point?
Last Answer : Melting point: 111.57 degrees Fahrenheit (44.15 degreesCelsius)
Description : The material used for a fuse wire should have (a) high resistivity (b) high ductility (c) high melting point (d) low melting point
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.