Which of the following measurements is expressed to three significant figures? 7.30 × 10–7 km 0.070 mm 0.007 m 7077 mg

Answer : The correct option is,

Explanation :

Significant figures : The figures in a number which express the value -the magnitude of a quantity to a specific degree of accuracy is known as significant digits.

Rules for significant figures are :

Digits from 1 to 9 are always significant and have infinite number of significant figures. All non-zero numbers are always significant. For example: 654, 6.54 and 65.4 all have three significant figures. All zero’s between integers are always significant. For example: 5005, 5.005 and 50.05 all have four significant figures. All zero’s preceding the first integers are never significant. For example: 0.0078 has two significant figures. All zero’s after the decimal point are always significant. For example: 4.500, 45.00 and 450.0 all have four significant figures. All zeroes used solely for spacing the decimal point are not significant. For example : 8000 has one significant figure.

As per question,

has 3 significant figures.

0.007 has 1 significant figure.

0.070 has 2 significant figures.

7077 has infinite significant figures.

Hence, the correct option is,