Question

To how many significant figures should each answer be rounded?

Equation A: (6.626× 10−34 J⋅s)(2.9979× 108 m/s)4.290×10−7 m=4.630322937063×10−19 J(unrounded)

After rounding, the answer to equation A should have

*2 significant figures.

*1 significant figure.

*4 significant figures.

*3 significant figures.

*5 significant figures.

Equation B: (6.022× 1023 atoms/mol)(0.795 g)20.18 g/mol=2.372×1022 atoms(unrounded)

After rounding, the answer to equation B should have

*1 significant figure.

*3 significant figures.

*5 significant figures.

*2 significant figures.

*4 significant figures.

Answer 1

Solution:

A) Result = 4.630322937063 x 10^-19 J

Thus,

2 significant figures= 4.6 x 10^-19 J

1 significant figures = 5 x 10^-19 J

4 significant figure = 4.630 x 10^-19 J

3 significant figures = 4.63 x 10^-19 J

5 significant figures = 4.6303 x 10^-19 J

B) Result = 2.372 x 10^22 atoms

Thus,

1 significant figure = 2  x 10^22 atoms

3 significant figures = 2.37 x 10^22 atoms

5 significant figure = 2.3720 x 10^22 atoms

2 significant figures = 2.4 x 10^22 atoms

4 significant figures = 2.372 x 10^22 atoms