Mixed Practice

Free set

Showing 2976 to 3000 of 3046 questions (page 120 of 122).

2976. The output of an AND gate is high only when

A. the inputs differ B. all inputs are low C. all inputs are high D. any input is high E. one input is low

2977. A diode acts approximately as a closed switch when it is

A. in breakdown only B. unbiased C. at absolute zero D. reverse biased E. forward biased above its threshold voltage

2978. In a photoelectric experiment, increasing the intensity of light of a fixed frequency increases the

A. work function B. number of electrons emitted per second C. stopping potential D. threshold frequency E. maximum kinetic energy of the electrons

2979. A perfect black body is one that

A. transmits all radiation B. emits no radiation C. absorbs all incident radiation and is also the best emitter D. is always black in colour E. reflects all radiation

2980. The energy of the photon emitted when an electron falls from level n2 to level n1 equals

A. the sum of the two level energies B. zero C. the kinetic energy of the nucleus D. the ionization energy E. the difference between the two level energies

2981. Hard X-rays differ from soft X-rays in having

A. no charge B. lower frequency C. the same wavelength D. shorter wavelength and greater penetrating power E. longer wavelength and less penetrating power

2982. In a helium neon laser, the active medium is

A. a plasma of metal vapour B. a gas mixture C. a liquid dye D. a semiconductor junction E. a solid crystal

2983. The number of nucleons in a nucleus is given by its

A. mass number B. atomic number C. charge number D. binding energy E. neutron number

2984. Alpha particles have very low penetrating power because they

A. are heavy and doubly charged, so they ionize strongly and lose energy quickly B. are electromagnetic waves C. have no mass D. carry no charge E. travel at the speed of light

2985. On a graph of the number of undecayed nuclei against time, the curve is

A. a straight line with negative slope B. a horizontal line C. a parabola D. an exponential decay curve E. a sine wave

2986. The chief difficulty in disposing of high level nuclear waste is that it

A. dissolves in water instantly B. is chemically inert C. remains dangerously radioactive for very long times D. evaporates quickly E. cannot be transported

2987. The binding energy of a nucleus is the energy

A. of one photon B. of the emitted alpha particle C. stored in the electron shells D. released when the nucleus decays E. required to separate it completely into its individual nucleons

2988. For an ionic compound such as sodium chloride, the correct term for NaCl is

A. a molecule B. an isotope C. a formula unit D. an atom E. a radical

2989. The number of moles of solute in 250 cm3 of a 0.4 mol dm-3 solution is

A. 1.6 B. 0.1 C. 0.4 D. 0.04 E. 1.0

2990. A gram molecule of a substance is

A. its relative molecular mass expressed in grams B. one molecule of the substance C. always 22.4 g D. the mass of one mole of atoms E. its atomic mass in grams

2991. A fractionating column improves separation because it provides

A. a drying agent B. a vacuum C. a larger heating surface D. many successive cycles of vaporization and condensation E. a catalyst

2992. A solute travels 4 cm while the solvent front travels 8 cm on a chromatogram. The Rf value is

A. 0.2 B. 4.0 C. 0.4 D. 2.0 E. 0.5

2993. One atmosphere of pressure is equal to

A. 10132 Pa B. 1000 Pa C. 760 Pa D. 101325 Pa E. 76 Pa

2994. A graph of pressure against volume at constant temperature for an ideal gas is

A. a straight line through the origin B. a hyperbola C. a vertical line D. a horizontal line E. a parabola

2995. Using the ideal gas equation, the number of moles in 4.48 dm3 of a gas at STP is

A. 0.4 B. 2.0 C. 0.2 D. 1.0 E. 0.1

2996. Ordinary glass is best described as

A. a gas B. a crystalline solid C. a network of ions D. an amorphous solid or supercooled liquid E. a true liquid

2997. The rise of a liquid in a narrow tube is greatest when the liquid

A. is very dense B. has high viscosity C. is non-polar D. does not wet the tube E. wets the tube and has high surface tension

2998. The permitted values of the spin quantum number are

A. plus one half and minus one half B. 0 and 1 C. only plus one half D. minus 1, 0 and plus 1 E. 1 and 2

2999. The notation used to represent a nuclide gives the mass number as a

A. subscript before the symbol B. superscript after the symbol C. superscript before the symbol D. separate word only E. subscript after the symbol

3000. The energy of an electron in the nth level of a hydrogen atom is proportional to

A. n squared B. the reciprocal of n squared C. the square root of n D. the reciprocal of n E. n

Previous 1 2 … 118 119 120 121 122 Next

Get full access to the MCQ bank

Premium questions, timed mock tests, and detailed explanations.

See premium plans