Spectroscopy | MCQs

Explanation

To obtain greater dispersion by a diffraction grating, the slit separation should be decreased. 

Dispersion:

• In diffraction gratings, dispersion is the separation of light wavelengths during diffraction, with greater dispersion resulting in wider color separation.

Slit separation:

• The distance between individual slits on the grating is called the slit separation.

Relationship between slit separation and dispersion:

• Smaller slit separations lead to larger angles of diffraction for a given wavelength, resulting in greater dispersion.
• Imagine the light waves as being "bent" more by the closer slits, causing them to spread out further

Explanation

The device that can be used for precise measurement of wavelength is a Michelson Interferometer. 

A Michelson interferometer uses the interference of light waves to measure very small distances, including wavelengths, with high accuracy. 

Explanation

In a line absorption spectrum, dark lines are due to transmittance.

In an absorption spectrum, dark lines appear against a continuous background.

These dark lines correspond to wavelengths of light that have been absorbed by the material through which the light passes.

The remaining wavelengths, which are not absorbed, are transmitted and create the bright background. 

Explanation

NMR spectroscopy provides detailed information about the connectivity of atoms within a molecule,

Including the types of carbon and hydrogen atoms present, their relative positions, and the presence of functional groups.

This level of detail allows for a comprehensive understanding of a molecule's structure, making it significantly more informative than the other options. 

Explanation

• Light from the Sun takes about 8 minutes to reach Earth due to the short distance of approximately 93 million miles.
• Light from Sirius, which is much farther away at about 8.6 light-years, takes approximately 8 years to reach us.

Explanation

Among the given options, the closest one is 45000 Å.

Explanation

The Pfund series of hydrogen spectral lines occurs when electrons fall to the n = 5 energy level from higher levels.

These transitions emit radiation in the infrared (IR) region of the electromagnetic spectrum.

Explanation

The height of the peak in a mass spectrum shows the relative abundance or intensity of ions with a specific mass-to-charge ratio (m/z) in the sample.

In simpler terms, a taller peak indicates a higher abundance or intensity of ions with that particular mass-to-charge ratio compared to other ions in the sample.

Explanation

Oxygen cannot be detected directly in an organic compound using common detection methods, unlike chlorine, nitrogen, and phosphorus.