Question

The mass of a box measured by a grocer's
balance is 2.3 kg. Two gold pieces of masses
20.15 g and 20.17 g are added to the box.
What is (i) the total mass of the box? (ii) the
difference in the masses of the pieces to
correct significant figures? (NCERT)​

Answer 1

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Explanation:

i)  

= 40.32

(real number)

= 4.032 × 101

(scientific notation)

= 4.032e1

(scientific e notation)

number of significant figures: 4

ii)

= -0.0

(real number)

= -2 × 10-2

(scientific notation)

= -2e-2

(scientific e notation)

number of significant figures: 1

Answer 2

Here is your Answer:-

Mass of box = 2.3 Kg

$Mass \: of \: 1 ^{st} \: piece \: = 20.15g \: = \: \frac{20.15}{1000} = 0.02015kg$

$Mass \: of \: 2 ^{nd} \: piece \: = 20.17g \: = \: 0.02017 \: kg$

$\:Total \: Mass \: = \: 2.3 \: + \: 0.02015 \: + \: 0.0201 \\ = \: 2.32032 \: kg \\ = 2.3 \: kg$

Now,

$Difference \: of \: mass \: = 20.17 \: - \: 20.15 \\ \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: \: = \: 0.02 \: g$