# Atomic Number

This worksheet consists of questions and answers related to Atomic number, mass number, Planck’s theory etc.

Atomic number is also known as proton number. Atomic number is the number of protons found in the nucleus of an atom. It is represented by the symbol ‘Z’. The atomic number is used to identify the chemical element.

Worksheet Questions

1. The correct representation of Moseley equation is:

(a)    $\sqrt{f} = a (Z- n)^2$

(b)   $\sqrt{f} = a (Z- n)^\frac{1}{3}$

(c)    $\sqrt{f} = a (Z- n)$

(d)   $f = \sqrt{a (Z- n)}$

2. If an atom has $11e^-$ and 12 neutrons, its mass no. will be:

(a)    22

(b)   23

(c)    21

(d)   24

3. Which of the following relates to photons both as wave motion and as a stream of particles?

(a)    $E = mc^2$

(b)   Diffraction

(c)    Interferences

(d)   E = hv

4. The frequency of yellow light having wavelength of 600 nm is?

(a)    $5 \times 10^{10} hz. \, \, or \, \, sec^{-1}$

(b)   $5 \times 10^{14} sec^{-1}$

(c)    $7.5 \times 10^7 sec^{-1}$

(d)   $6 \times 10^{14} sec^{-1}$

5. The correct order of increase of frequency will be:

(a)    U.V. Rays > X-Rays > $\gamma$-Rays > Cosmic Rays

(b)   Cosmic Rays >  $\gamma$-Rays > X-Rays > U.V. Rays

(c)    U.V. Rays < X-Rays < $\gamma$-Rays < Cosmic Rays

(d)   X-Rays < $\gamma$-Rays < U.V. Rays < Cosmic Rays