# Give reason: a)  The emission spectra of atoms are also known as line spectra b)  why do we see a car moving as the wave on the road.

Dear Student,

When the electrons in the atom are excited, for example by being heated, the additional energy pushes the electrons to higher energy orbitals. When the electrons fall back down and leave the excited state, energy is re-emitted in the form of a photon. The wavelength (or equivalently, frequency) of the photon is determined by the difference in energy between the two states. These emitted photons form the element's spectrum.

The fact that only certain colors appear in an element's atomic emission spectrum means that only certain frequencies of light are emitted. Each of these frequencies are related to energy,

Line spectrum is special type of emission spectrum which consisting of separate isolated lines,
I dont think your statement is always correct,emission spectra is not known as line spectra but specifically for Hydrogen atom, it could be true,

Please post photo of the question where it is present,

(b) is also incorrect statement in your question,actually we DO NOT
see a car moving as the wave on the road because  the size of the car is very big. The de broglie wavelength of a particle is given by λ = h/mv, where h is the Planck's constant = 6.63 x 10-34 J.s, m the mass of the particle and v its velocity. Here the numerator is very small and the denominator is large and so the wavelength of car is too small to observe.