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Showing 176 to 200 of 3046 questions (page 8 of 122).

176. A coordinate covalent bond is present in

A. methane B. the ammonium ion C. sodium chloride D. chlorine E. ethene

177. The ionic character of a bond increases with

A. decreasing electronegativity difference B. increasing electronegativity difference C. increasing bond order D. decreasing atomic size only E. increasing covalent radius

178. In benzene, all six carbon to carbon bonds are of equal length because of

A. sp3 hybridization B. resonance delocalization C. hydrogen bonding D. free rotation E. ionic character

179. The hybridization of carbon in ethyne is

A. sp3 B. sp2 C. sp D. sp3d E. unhybridized

180. For an exothermic reaction, the enthalpy change is

A. positive B. negative C. zero D. always equal to the activation energy E. undefined

181. Hess's law states that the enthalpy change of a reaction

A. depends on the path taken B. is independent of the path taken C. is always negative D. equals the activation energy E. depends only on temperature

182. The standard enthalpy of formation of an element in its most stable form is

A. always negative B. always positive C. zero D. equal to its atomization energy E. equal to its bond energy

183. The enthalpy of neutralization of a strong acid by a strong base is nearly constant because

A. all acids have the same concentration B. the reaction is always the combination of H+ and OH- to give water C. the salts formed are identical D. water is a catalyst E. the reaction is endothermic

184. The lattice energy of an ionic compound is determined indirectly using the

A. Born Haber cycle B. Carnot cycle C. Haber process D. Kelvin scale E. Hess cycle for combustion only

185. A system that can exchange energy but not matter with its surroundings is called

A. an open system B. a closed system C. an isolated system D. an adiabatic system only E. a homogeneous system

186. For the reaction N2 + 3H2 giving 2NH3, increasing the pressure shifts the equilibrium

A. to the left B. to the right C. not at all D. first left then right E. towards the gas with higher molar mass

187. A catalyst added to a reversible reaction at equilibrium

A. shifts the equilibrium to the right B. shifts the equilibrium to the left C. increases the value of Kc D. does not change the position of equilibrium E. reduces the yield

188. The pH of a 0.001 mol dm-3 solution of hydrochloric acid is

A. 1 B. 2 C. 3 D. 4 E. 11

189. At 25 degrees Celsius, the sum of pH and pOH for an aqueous solution is

A. 7 B. 10 C. 14 D. 1

190. A buffer solution can be prepared from

A. a strong acid and its salt B. a weak acid and its salt with a strong base C. two strong acids D. a strong base alone E. a neutral salt alone

191. The solubility of a sparingly soluble salt decreases on adding a soluble salt with a common ion. This is called

A. the buffer effect B. the common ion effect C. hydrolysis D. the salt bridge effect E. Le Chatelier suppression of Ksp

192. Kc has no units when

A. the reaction is exothermic B. the total number of moles of gaseous reactants equals that of products C. the reaction is at high pressure D. a catalyst is used E. the reaction is irreversible

193. Molality is defined as the number of moles of solute per

A. cubic decimetre of solution B. kilogram of solvent C. litre of solvent D. kilogram of solution E. mole of solvent

194. Which of the following is not a colligative property?

A. elevation of boiling point B. depression of freezing point C. osmotic pressure D. lowering of vapour pressure E. refractive index

195. The molal boiling point elevation constant of water is

A. 0.52 K kg mol-1 B. 1.86 K kg mol-1 C. 5.12 K kg mol-1 D. 0.86 K kg mol-1 E. 2.53 K kg mol-1

196. Raoult's law states that the partial vapour pressure of a component in a solution is proportional to its

A. mass B. mole fraction C. molarity D. molality E. volume fraction

197. A mixture that distils at constant composition and cannot be separated further by fractional distillation is called

A. an ideal solution B. an azeotrope C. a colloid D. a saturated solution E. an emulsion

198. An ideal solution is one in which

A. the enthalpy of mixing is zero and Raoult's law is obeyed B. the volume decreases on mixing C. hydrogen bonding is formed on mixing D. the components react E. the vapour pressure is zero

199. The oxidation number of manganese in potassium permanganate is

A. +2 B. +4 C. +6 D. +7 E. +3

200. The standard electrode potential of the standard hydrogen electrode is taken as

A. +1.00 V B. -1.00 V C. 0.00 V D. +0.76 V E. -0.76 V

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