Revision Quiz PA I

Which of the following is an example of a primary standard used in titrimetric analysis?

• Potassium permanganate       

                   

• Arsenic trioxide

• Sodium hydroxide. 

•    Hydrochloric acid

Answer explanation

Arsenic trioxide is a primary standard because it has a known and stable composition, making it suitable for accurate titrimetric analysis. The other options are not primary standards.

Reagent error can be minimized by________

• Using Calibrated instruments

• Running parallel determinations     

• Running blank determinations        

• Replacing the sample

Answer explanation

Running blank determinations helps identify any background interference or reagent errors, ensuring that the results reflect only the sample's contribution. This minimizes reagent error effectively.

The pH at the equivalence point of the titration of a weak acid with a strong base

is usually ______.

• 3.5

• 7.0

• 5.5

• 8.5

The curve obtained by plotting pH on the y-axis against the volume of titrant on the x-axis is called the _______.

• Standard curve

• Neutralization curve          

• calibration curve

• precipatation curve

Answer explanation

The curve plotting pH against the volume of titrant is known as the Neutralization curve, as it illustrates the pH changes during an acid-base titration, highlighting the point of neutralization.

Permanganate titration requires following reagent

• Sodium Hydroxide

• Sulphuric Acid

• Hydrochloric Acid

• Ethanol

Quantitative analysis of polarograph is based on ________.

• Electrode potential

• decomposition potential

• Half wave potential

• Limiting current

Answer explanation

Quantitative analysis in polarography relies on measuring diffusion current which can be calculated from limiting current. all other options are incorrect

__________ is a suitable indicator for the titration of a strong acid and a weak alkali.

• Methyl orange

• Phenolphthalein

• Litmus solution

• Universal indicator

Answer explanation

Methyl orange is a suitable indicator for titrating a strong acid with a weak alkali because it changes color at a pH range of 3.1 to 4.4, which is ideal for detecting the endpoint in such titrations.

The solvents which are basic in nature and used to increase the acidity of weakly acidic substances are known as

• Protogenic solvents

• Protophilic solvents

• Aprotic solvents

• None of the above

Answer explanation

Protophilic solvents are basic solvents that can accept protons, thus increasing the acidity of weakly acidic substances. This makes them the correct choice for the question.

Quantitative determination principle

in titrimetric methods are based…

• On the basis of measurement of

  Volume

• On the basis of absorbance of

  sample

• On the basis of pharmacological

  response

• On the basis of measurement of

  conductance

Answer explanation

The correct choice is 'On the basis of measurement of Volume' because titrimetric methods quantify substances by measuring the volume of titrant required to react completely with the analyte.

parts per hundred

• ppm

• molarity

• percent solution

• normality

Answer explanation

'Parts per hundred' refers to a percentage, which is expressed as a 'percent solution'. Other options like ppm, molarity, and normality represent different concentration measures, making 'percent solution' the correct choice.