Chemical Process Calculation Questions and Answers Part-4

1. The given numbers are shown with their significant figures respectively. Find out the wrong one option?
a) 26.24 and 4
b) 24000. and 5
c) 0.000460 and 3
d) 28000.0 and 5

Answer: d
Explanation: Zero after a decimal point counts in significant figure.

2. The theoretical production rate of a chemical is 1µg/(mL)(min.). What is the actual production rate of the chemical in lb mol/ (day)(ft3) with an efficiency of 98%?
a) 0.0880
b) 0.0800
c) 0.0449
d) 0.529

Answer: a
Explanation: 1 lb mole = 454 g mole and 1 L = 3.531×10-2 ft3.

3. Standard form of 2145.67 is
a) 2.14*103
b) 2.14567*103
c) 0.214*104
d) None of the mentioned

Answer: b
Explanation: 21456.7 = 2.14567*103.

4. Correctly rounded, the quotient 5.000 g / 50.0 mL is
a) 0.10 g/mL
b) 0.1 g/mL
c) 0.100 g/mL
d) 0.1000 g/mL

Answer: c
Explanation: The measurement with the least number of significant digits determines the number of significant digits in the quotient.

5. Correctly rounded, the product 3.000 cm × 30.0 cm is
a) 9.0 x 101 cm2
b) 9.000 x 101 cm2
c) 9 x 101 cm2
d) 9.00 x 101 cm2

Answer: d
Explanation: The measurement with the least number of significant digits determines the number of significant digits in the quotient.

6. Number of digits that are reasonably sure, called significant figures.
Above given definition is
a) Correct
b) Incorrect
c) Probably correct
d) None of the mentioned

Answer: a
Explanation: Number of digits that are reasonably sure, called significant figures.

7. 0.009046879855, round off the number to three significant figures
a) 0.0905
b) 0.0904
c) 0.09046
d) 0.09035

Answer: a
Explanation: In such situation we round up the last digit from 4 up to 5.

8. How many significant numbers are there in 420?
a) 1
b) 2
c) 3
d) 0

Answer: b
Explanation: Zero does not count in significant number here.

9. Using the proper number of significant figures 6 X 6 equals to
a) 3
b) 4
c) 36
d) 40

Answer: d
Explanation: Significant figure in 40 is only one that is same as 6.

10. How many significant figures are there in 0.002000?
a) 1
b) 2
c) 3
d) 4

Answer: d
Explanation: Zero after the point counts