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 :

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,

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

the answer is c

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