Structure of Atom - Online Test

Answer : Option B
Explaination / Solution:

Cathode rays (also called an electron beam or e-beam) are streams of electrons observed in vacuum tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, the glass behind of the positive electrode is observed to glow, due to electrons emitted from and traveling away from the cathode (the electrode connected to the negative terminal of the voltage supply). Cathode ray tubes (CRTs) use a focused beam of electrons deflected by electric or magnetic fields to create the image in a television set

Answer : Option C
Explaination / Solution:

The electron is a subatomic particle, symbol e− or β− , with a negative elementary electric charge.

The electron has a mass that is approximately 11836 that of the proton.

So mass of electron = 11836×1.6726219×10−27=9.1094×10−31kg

Answer : Option C
Explaination / Solution:

Max Planck theorized that energy was transferred in chunks known as quanta, equal to hν. The variable h is a constant equal to 6.63 × 10-34 J·s and the variable ν$\nu$represents the frequency in 1/s.

This equation allows us to calculate the energy of photons, given their frequency.

If the wavelength is given, the energy can be determined by first using the wave equation(c=λ×ν)to find the frequency, then using Planck’s equation to calculate energy.

Answer : Option B
Explaination / Solution:

Wave number is defined as the reciprocal of wavelength.

ν¯=1λ

where, λ= wavelength = 5800 Å = 5.8×10−7m

So, ν¯=15.8×10−7=1.72×106m−1

Answer : Option A
Explaination / Solution:

Boron is a chemical element with symbol B and atomic number 5. So electronic configuration of boron is 1s22s22p1

Answer : Option C
Explaination / Solution:

Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nm. In terms of frequency, this corresponds to a band in the vicinity of 430–770 THz.

Answer : Option D
Explaination / Solution:

Radio frequency (RF) is any of the electromagnetic wave frequencies that lie in the range extending from around3 kHz to 300 GHz, which include those frequencies used in radio communication or radar. RF usually refers to electrical rather than mechanical oscillations

Answer : Option D
Explaination / Solution:

Orbitals with subshell quantum number l = 0 are called s orbitals. All s orbitals are spherical in shape and have spherical symmetry. This means that the wave function will depend only on the distance from the nucleus and not on the direction.

Answer : Option D
Explaination / Solution:

We know Planck's equation is

E=hν

where E is energy, h is Planck’s constant, and ν$\nu$ is frequency.

Put given values,

E = 6.626×10−34×3×1015=1.988×10−18J

Answer : Option D
Explaination / Solution:

Energy (E) of a photon having wavelength (λ) is given by the expression, E=hcλ

where , h = Planck’s constant =6.626×10−34Js

c = velocity of light in vacuum = 3×108m/s

Wavelength λ=0.50A∘=0.50×10−10m

Substituting the values in the given expression of E:

6.626×10−34×3×1080.50×10−10=3.98×10−15J