PAST QUESTIONS ON ERRORS

1.The degree of closeness between replicate values of measurements or analysis is called

A)Error

B)Determinate error

C)Precision

D)Accuracy

Ans:C

2.Determinate errors can be minimized by any of the following except

A)Running parallel determination

B)Calibration of apparatus

C)Use of external standard

D)Running a blank determination

Ans:C

3.The visual inspection of any unwanted data from a series of measurements is called

A)Trimming

B)Accuracy

C)Inspection

D)Precision

Ans:A

4.A student took a reading for 20.44% instead of 20.34%.Calculate the absolute error and relative error respectively.

A)0.10%,0.05

B)0.10%,0.005

C)1.0%,0.005

D)1.0%,0.05

Ans:

i)Absolute error E=measured value -true value

=20.44-20.34=0.10%

ii)Relative error =Absolute error/True value

=0.10/20.34. =0.005

Correct answer is B

5.The molar concentration of a solution is determined by four separate titrations,the results being 0.2041,0.2039,0.2049,and 0.2043.Calculate the mean and median of the data

A)0.2042 $ 0.2044

B)0.2043 $0.2041

C)0.2043 $ 0.2043

D)0.2043 $ 0.2042

Ans:

I) Mean =0.2041+0.2049+0.2039+0.2043/4

=0.2043

ii) Median =0.2042

Correct answer is D

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PAST QUESTIONS ON ACIDS BASES AND SALTS

1.A substance that can increase the concentration of hydrogen ion when dissolved in water is?

A)Acid

B)Proton

C)Electron

D)Base

Ans;A

2…………….acid has three replaceable hydrogen ion

A)Monoprotic

B)Triprotic

C)Diprotic

D)Tetraprotic

Ans;B

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3.Find the POH of a water sample with OH concentration of 1.47×10^-6 mol/dm3

A)8.83

B)10.9

C)6.80

D)5.17

Ans:B

4……..defined acid as a proton donor

A)Bronsted Lowry

B)Arhhenious

C)GN lewis

D)Salto

Ans;A

5……..changes blue litmus paper to red

A)Arrhenious base

B)Arrhenious Acid

C)Bronsted Lowry acid

D)GN lewis acid

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