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Showing 2301 to 2325 of 3046 questions (page 93 of 122).

2301. Rutherford's gold foil experiment established the existence of

A. a small dense positively charged nucleus B. the neutron C. orbitals D. the electron E. energy levels

2302. The energy of a photon of frequency nu is given by

A. h/nu B. h nu C. h nu2 D. nu/h E. h/nu2

2303. The shape of a p orbital is

A. spherical B. tetrahedral C. planar triangular D. double dumb bell E. dumb bell

2304. Hund's rule requires that

A. d orbitals fill before s orbitals of the same shell B. the lowest energy orbital is filled last C. degenerate orbitals are singly occupied with parallel spins before pairing D. electrons pair up before occupying empty degenerate orbitals E. no two electrons can have the same spin

2305. The bond angle in a molecule with sp3 hybridization and no lone pairs is

A. 107 degrees B. 120 degrees C. 109.5 degrees D. 104.5 degrees E. 90 degrees

2306. The dipole moment of carbon dioxide is zero because the molecule is

A. tetrahedral B. linear and symmetrical C. non-polar in its bonds D. ionic E. angular

2307. The shape of the ammonia molecule according to VSEPR theory is

A. trigonal pyramidal B. trigonal planar C. tetrahedral D. linear E. bent with 104.5 degrees

2308. As bond order increases, the bond length

A. remains constant B. first increases then decreases C. increases D. decreases E. becomes zero

2309. A coordinate covalent bond is present in

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

2310. The ionic character of a bond increases with

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

2311. In benzene, all six carbon to carbon bonds are of equal length because of

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

2312. The hybridization of carbon in ethyne is

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

2313. For an exothermic reaction, the enthalpy change is

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

2314. Hess's law states that the enthalpy change of a reaction

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

2315. The standard enthalpy of formation of an element in its most stable form is

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

2316. The enthalpy of neutralization of a strong acid by a strong base is nearly constant because

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

2317. The lattice energy of an ionic compound is determined indirectly using the

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

2318. A system that can exchange energy but not matter with its surroundings is called

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

2319. For the reaction N2 + 3H2 giving 2NH3, increasing the pressure shifts the equilibrium

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

2320. A catalyst added to a reversible reaction at equilibrium

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

2321. The pH of a 0.001 mol dm-3 solution of hydrochloric acid is

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

2322. At 25 degrees Celsius, the sum of pH and pOH for an aqueous solution is

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

2323. A buffer solution can be prepared from

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

2324. 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. hydrolysis C. the salt bridge effect D. Le Chatelier suppression of Ksp E. the common ion effect

2325. Kc has no units when

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

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