Free Analytical Chemistry MCQs with Answers

41. If the values of standard deviations for the first and second method differ, then which of the following test helps one to know whether this difference is significant?

• A. Student's t-test
• B. F-test
• C. Chi square test
• D. Standard deviation

Explanation: The F-test is a statistical test used to compare the variances (the square of the standard deviation) of two samples. It is the appropriate test to determine if the difference in precision between two methods is statistically significant.

42. Which of the following test is used to find out whether the observed data differ significantly from the one obtained from theoretical distribution?

• A. Student's t-test
• B. F-test
• C. Chi-square test
• D. Standard deviation

Explanation: The chi-square (χ²) test is a statistical hypothesis test used to determine if there is a significant difference between the expected frequencies and the observed frequencies in one or more categories. It is a "goodness-of-fit" test.

43. Which of the following shows maximum penetration?

• A. Electrons
• B. Protons
• C. Alpha particles
• D. Beta-particles

Explanation: Beta particles penetrate farther than alpha particles and protons because they are lighter and less charged. Alpha particles are heavy and stopped quickly, while protons are massive but slow down faster. Electrons (in general atomic context) are less penetrating than beta radiation from radioactive decay.

44. The e/m value for the canal rays is maximum for:

• A. Hydrogen
• B. Nitrogen
• C. Helium
• D. Argon

Explanation: e/m is largest for the particle with the smallest mass and single positive charge. Hydrogen ion is the lightest, so it has the highest e/m. Heavier ions like nitrogen, helium, and argon have smaller e/m values

45. π-π* electronic transition occurs in molecules that have:

• A. Double bond
• B. Triple bond
• C. Aromatic ring
• D. All of the above

Explanation: π → π* transitions need π electrons, which are present in double bonds, triple bonds, and aromatic systems. The transition absorbs UV or visible light depending on conjugation. All these structures can undergo π → π* electronic excitation

46. A mixture of camphor and benzide acid can be separated by:

• A. Fractional crystallization
• B. Sublimation
• C. Chemical method
• D. Extraction with solvent

Explanation: Camphor can sublime (change directly from solid to vapor) on heating.Benzoic acid remains as a solid because it does not sublimate. Heating the mixture allows camphor to separate, leaving benzoic acid behind.

47. The property of liquid that is measured by a polarimeter?

• A. Conductance
• B. Refractive Index
• C. Optical activity
• D. Change in volume

Explanation: Optical activity is the ability of a substance to rotate planepolarized light, typical for chiral compounds. A polarimeter measures the angle of rotation, which indicates the concentration or purity of the optically active substance

48. Line spectrum of sodium contains _ colored lines separated by a definite distance

• A. one yellow
• B. two yellow
• C. two brown
• D. two golden

Explanation: Sodium emits two yellow lines in its line spectrum, known as the D1 and D2 lines. These lines are very close in wavelength (~589.0 nm and 589.6 nm). The separation is small but definite, giving the characteristic sodium doublet

49. The relative abundance of ion with a definite m/e value is measured by?

• A. Quantity of fast moving electrons
• B. Strength of electric current measured
• C. High pressure of vapors
• D. Electron gas

Explanation: Ions with a specific m/e value hit the detector and produce an electric current. The magnitude of the current indicates the relative number of ions (abundance). Other options like fast-moving electrons or vapor pressure are not related to measuring ion abundance.

50. Which of the following is locating agent?

• A. H2S
• B. CS2
• C. Rubeanic acid
• D. Ninhydrin

Explanation: Rubeanic acid is a specific locating agent that forms colored complexes with metals like Cu²⁺ and Ni²⁺. It is used to visualize or detect these metal ions in qualitative analysis. Other options are either reagents, solvents, or used for different purposes.