This set of Class 11 Chemistry Chapter 1 Multiple Choice Questions & Answers (MCQs) focuses on “Uncertainty in Measurement”.

1. Write 6354000000 in scientific notation.

a) 6.354 x 10^{9}

b) 6354 x 10^{6}

c) 0.64 x 10^{10}

d) 6354000 x 10^{3}

View Answer

Explanation: Scientific notation should have the least possible significant figures as the zeroes are made as to the power of ten. Or simply the power of ten in scientific notation is equal to the number of times the decimal point moved to produce a number between 1 and 10.

2. _________ is referred to as the closeness of different measurements for the same quantity.

a) Accuracy

b) Precision

c) Analysis

d) Dimension

View Answer

Explanation: Precision is referred to as the closeness of different measurements for the same quantity. Accuracy is the degree to which it’s taken as standard or almost equivalent to it.

3. How many seconds are there in a half day?

a) 86,400 seconds

b) 43,200 seconds

c) 172,800 seconds

d) 3660 seconds

View Answer

Explanation: Half day means 12 hours. One hour means 60 seconds. And each minute is of 60 seconds. In the above question, we need the total number of seconds so 12 x 60 x 60 seconds = 43,200 seconds.

4. A piece of iron is 5 inches long. How much would it be in centimeters?

a) 12.7 cm

b) 6.35 cm

c) 5 cm

d) 500 cm

View Answer

Explanation: 1 inch = 2.54 cm : 1 cm = 0.3931 inch. As we now know, how much is 1inch in centimeters, then we need to multiply 5 to 2.54 cm in order to convert it into centimeters. 5 x 2.54 cm = 12.7 cm.

5. How many significant figures does 0.057 have?

a) 2

b) 4

c) 3

d) 0

View Answer

Explanation: The non-zero digits and any zeros between them are all significant. Leading zeros are not significant. Counting all the significant digits gives us 2.

6. How many significant figures does 63180 have?

a) 5

b) 4

c) 1

d) 2

View Answer

Explanation: The non-zero digits and any zeros between them are all significant. Since there is no decimal, zeros are not significant. Therefore it’s 4.

7. The exact value is 150m. A students record it as 140.1m in 1st turn and 140.8m in the 2^{nd} turn. Comment his/her recordings.

a) precise

b) accurate

c) neither precise nor accurate

d) both precise and accurate

View Answer

Explanation: These values are precise as they are close to each other but are not accurate. Precision is referred to as the closeness of different measurements for the same quantity. Accuracy is the degree to which it’s taken as standard or almost equivalent to it.

8. The exact value is 150m. A students record it as 149.1m in 1st turn and 150.8m in the 2^{nd} turn. Comment his/her recordings.

a) precise

b) accurate

c) neither precise nor accurate

d) both precise and accurate

View Answer

Explanation: These values are accurate as they are nearer to the exact value. Precision is referred to as the closeness of different measurements for the same quantity. Accuracy is the degree to which it’s taken as standard or almost equivalent to it.

9. Multiply 1.2 and 3.91. Obtain the result as per the rules of significant figures.

a) 4.692

b) 4.69

c) 5

d) 4.7

View Answer

Explanation: 1.2 x 3.91 = 4.692. Since 1.2 has two significant figures, the result should not have more than two significant figures, thus, it is 4.7. As per the rules of significant figures, the resultant answer should not have more significant figures the number with a less significant figured number.

10. How many significant figures are there in 60.6?

a) 4

b) 2

c) 3

d) 1

View Answer

Explanation: The non-zero digits and any zeros between them are all significant. Leading zeros are not significant. Counting all the significant digits gives us 3.

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