De Broglie suggested that if waves (photons) could behave as particles, as demonstrated by the photoelectric effect, then the converse, namely that particles could behave as waves, should be true. He associated a wavelength λ to a particle with momentum p using Planck's constant as the constant of proportionality: (4.5.1) λ = h p

An angle's measurement in radians is numerically equal to the length of a corresponding arc of a unit circle. One radian is equal to 180/π (~57.296) degrees. History/origin: Measuring angles in terms of arc length has been used by mathematicians since as early as the year 1400. The concept of the radian specifically however, is credited to.

Benzene and toluene form nearly ideal solutions. At 20°C, the vapour pressure of benzene is 75 torr and that of toluene is 22 torr. The partial vapour pressure of benzene at 20°C for a solution containing 78g of benzene and 46 g of toluene in torr is (a) 50 (b) 25 (c) 37.5 (d) 53.5