Free Analytical Chemistry MCQs with Answers

81. Which one is used as stationary phase in paper chromatography?

• A. Alcohol
• B. Adeline
• C. Piece of paper
• D. Water absorbed on paper

Explanation: Water absorbed on paper: This option is correct. In paper chromatography, the stationary phase is usually achieved by impregnating the paper with water or a suitable aqueous solution. The water absorbed on the paper fibers acts as the stationary phase, while the mobile phase (solvent) carries the components of the sample along the paper.

82. Which of the statements about paper chromatography is not correct:

• A. Paper chromatography is an example of partition chromatography.
• B. Paper chromatography is most commonly used to separate biologically active substances.
• C. Paper chromatography can also be applied for separating some inorganic ions.
• D. Paper chromatography is always used for quantitative analysis.

Explanation: There are limitations to paper chromatography that include;Large quantities of sample cannot be applied on paper chromatography.In quantitative analysis paper chromatography is not effective.Complex mixture cannot be separated by paper chromatography.

83. Which of the following reagents can be used to identify Ni+2 ions in solution?

• A. Ethylenediamine
• B. potassium ferrocyanide
• C. dimethylglyoxime
• D. potassium permanganate

Explanation: When identifying Ni+2 ions, dimethylglyoxime is the reagent of choice. Adding dimethyl glyoxime to a solution of Ni+2 ions along with ammonium hydroxide results in the formation of a bright red precipitate. This distinctive color change indicates the presence of Ni+2 ions. The other options, such as ethylenediamine, potassium ferrocyanide, and potassium permanganate, do not react in a way that specifically identifies Ni+2 ions, making them incorrect choices.

84. The fixing solution used in developing a negative in photography contains:

• A. Hydroquinone
• B. Sodium thiosulphate
• C. Pyfogallal
• D. AgBr

Explanation: Sodium thiosulfate (sodium hyposulfite), Na2S2O3, is used by photographers to fix developed negatives and prints; it acts by dissolving the part of the silver salts coated onto film which remain unchanged by exposure to light. Fixation is commonly achieved by treating the film or paper with a solution of thiosulfate salt. Popular salts are sodium thiosulfate-commonly called hypo-and ammonium thiosulfate-commonly used in modern rapid fixer formulae.

85. Continuous adsorption spectrum is obtained from:

• A. excited atoms
• B. Excited molecules
• C. Ground state molecules
• D. Ground state atoms

Explanation: Excited atoms: When atoms are excited, either by heating or by other means such as electrical discharge, they absorb energy and transition to higher energy levels. As these excited atoms return to their ground state, they emit energy in the form of electromagnetic radiation. The absorption and emission of specific wavelengths of light result in a continuous adsorption spectrum. In summary, a continuous adsorption spectrum is obtained from excited atoms, where the absorption of energy and subsequent emission of light results in a continuous range of wavelengths.

86. The device used for the detection of isotopes is

• A. Mass spectrometer
• B. Cyclotron
• C. Betatron
• D. Reactor

Explanation: The mass spectrometer is a device commonly used for the detection and analysis of isotopes. It separates ions based on their mass-to-charge ratio, allowing for the identification and quantification of different isotopes in a sample.

87. The instrument that is used to determine the weight of a proton as well as a positive ion and is capable of recording its result as the photograph is called:

• A. Mass spectroscope
• B. Atomic spectroscope
• C. Spectrophotographic analyzer
• D. Spectrophotometer

Explanation: A mass spectroscope is an instrument used to determine the weight (mass) of a proton as well as positive ions. It works based on the principle of mass spectrometry, which involves ionizing a sample and separating the ions based on their mass-to-charge ratio. The resulting ion spectrum can be recorded and analyzed.

88. The ring test is shown by compounds having:

• A. Sulphate radical
• B. Chloride radical
• C. Nitrate radical
• D. None of the above

Explanation: The brown ring test is a qualitative analysis technique used to detect the presence of nitrate ions. When a solution containing nitrate ions is treated with freshly prepared ferrous sulfate and then carefully added to concentrated sulfuric acid, a brown ring forms at the interface between the two layers. This indicates the presence of the nitrate radical. Sulphate and chloride radicals do not produce such a ring. The sulphate radical is typically detected by forming a white precipitate with barium chloride, while the chloride radical forms a white precipitate with silver nitrate.

89. You are required to test the presence of NH4+ Ion in water. Which of the following reagent will solve your problem?

• A. Imethylglyoxime
• B. Tollen's reagent
• C. Nessler's reagent
• D. Magneson reagen

Explanation: Nessler's reagent can be used to detect the presence of NH4+ ions in water as brown ppt is formed. Therefore the correct answer will be C.

90. The differences in energy between different states of bond vibrations in a molecule correspond to which electromagnetic region?

• A. Microwave
• B. Infrared
• C. Visible
• D. X-rays

Explanation: The difference in energy between two vibrational states is equal to the energy associated with the wavelength of radiation that was absorbed, it lies in the infrared region, therefore the answer is B.