1st TEST PUNJAB ACHIEVEMENT SURVEY CLASS 11th Non-Medical (ਪਹਿਲਾ ਟੈਸਟ ਪੰਜਾਬ ਉਪਲਬਧੀ ਸਰਵੇਖਣ ਜਮਾਤ 11ਵੀਂ Non-Med)
*Required
PHYSICS
The number of significant figures in 0.06900 is: *
1 point
5
4
2
3
Q *
1 point


A

B

C

D
A man went from his home to market 3 km away with a uniform speed of 4 km/h and on finding the market closed he instantly turns back with a velocity of 6 km/h. Find average speed of his journey. *
1 point
5 km/h
4.5 km/h
6 km/h
4.8 km/h
Answers
Answer:
NCERT Solutions for Class 11 Physics Chapter 1 Units and Measurements
October 20, 2015 by Sastry CBSE
NCERT Solutions for Class 11 Physics Chapter 1 Units and Measurements
Multiple Choice Questions (MCQs)
Q.1.The number of significant figures in 0.06900 is
(a) 5 (b) 4 (c) 2 (d) 3
Thinking Process
If the number is less than 1, the zero(s) on the right of decimal point and before the first non-zero digit are not significant.
Ans. (b) In 0.06900, the underlined zeroes are not significant. Hence, number of significant figures are four (6900).
Q. 2 The sum of the numbers 436.32, 227.2 and 0.301 in appropriate significant figures is
(a) 663.821 (b) 664 (c) 663.8 (d) 663.82
Ans. (b) The sum of the numbers can be calculated as 663.821 arithmetically. The number with least decimal places is 227.2 is correct to only one decimal place.
The final result should, therefore be rounded off to one decimal place i.e., 664.
Note In calculating the sum, we should not confuse with the number of decimal places
and significant figures. The result should have least number of decimal places.
Q, 3 The mass and volume of a body are 4.237 g and 2.5 cm3, respectively. The density of the material of the body in correct significant figures is
(a) 1.6048 g cm’3 (b) 1.69 g cm’3 (c) 1.7 g cm-3 (d) 1.695
Thinking Process
In multiplication or division, the final result should retain as many significant figures as are there in the original number with the least significant figures.
Ans. (c) In this question, density should be reported to two significant figures.
Density = 4.237g/2.5 cm3 = 1.6948
As rounding off the number, we get density = 1.7
Q. 4 The numbers 2.745 and 2.735 on rounding off to 3 significant figures will give
(a) 2.75 and 2.74 (b) 2.74 and 2.73 (c) 2.75 and 2.73 (d) 2.74 and 2.74
Ans. (d) Rounding off 2.745 to 3 significant figures it would be 2.74. Rounding off 2.735 to 3 significant figures it would be 2.74.
Q. 5 The length and breadth of a rectangular sheet are 16.2 cm and 10.1 cm, respectively. The area of the sheet in appropriate significant figures and error is
(a) 164± 3 cm2 (b) 163.621 2.6 cm2 (c) 163.61 2.6 cm2 (d) 163.621 3 cm2
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Q. 9 Which of the following measurement is most precise?
(a) 5.00 mm (b) 5.00 cm (c) 5.00 m (d) 5.00 km
Ans. (a) All given measurements are correct upto two decimal places. As here 5.00 mm has the <• smallest unit and the error in 5.00 mm is least (commonly taken as 0.01 mm if not specified), hence, 5.00 mm is most precise.
Note In solving these type of questions, we should be careful about units although their magnitude is same.
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