What are the statements?.
Answer:
Answer is in the attachment
Amount of Niobium-91 initially
= 300/91 =3.2967mol
2040 years = 3 ×680 = 3 half-lives
therefore, amount left = 0.4121mol
mass of Niobium-91 remaining = 0.4121 ×91 =37.5g
1 mm (millimeter) = 0.000001 km (kilometer)
12.5 mm = <span>0.0000125 km
1 mm = </span><span>0.00001 hm (hectometer)
12.5 mm = </span><span>0.000125 hm
1 mm = </span>0.001 m (meter)
12.5 mm = 0.0125 m
1 mm = 0.1 cm (centimeter)
12.5 mm = 1.25 cm
So the only one of the answer choices that doesn't equal 12.5 mm is 0.00125 hm, since 12.5 mm is <span>0.000125 hm.
Answer:
</span><span>0.00125 hm
</span><span>
Hope this helps!</span>
