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Showing 351 to 375 of 1398 questions (page 15 of 56).

351. Which type of solid has the highest melting point?

A. amorphous B. molecular C. covalent network D. metallic E. ionic

352. The maximum number of electrons that can occupy the shell with n = 3 is

A. 6 B. 8 C. 32 D. 10 E. 18

353. For an electron in a 3d orbital, the azimuthal quantum number l is

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

354. The ground state electronic configuration of chromium (Z = 24) is

A. [Ar] 3d6 B. [Ar] 3d5 4s1 C. [Ar] 3d3 4s3 D. [Ar] 4s2 4p4 E. [Ar] 3d4 4s2

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

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

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

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

357. The shape of a p orbital is

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

358. Hund's rule requires that

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

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

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

360. 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

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

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

362. As bond order increases, the bond length

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

363. A coordinate covalent bond is present in

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

364. The ionic character of a bond increases with

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

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

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

366. The hybridization of carbon in ethyne is

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

367. For an exothermic reaction, the enthalpy change is

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

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

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

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

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

370. 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 salts formed are identical C. all acids have the same concentration D. the reaction is endothermic E. water is a catalyst

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

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

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

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

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

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

374. A catalyst added to a reversible reaction at equilibrium

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

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

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

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