2. HOW MANY SIG FIGS ? 200 3.002.00034.7000 1 sig fig Zeros are place holders 2 sig fig Zeros are place holders 4 sig fig Zeros are between sig figs 4 sig fig Zeros are exact zeros

3. HOW MANY SIG FIGS ? 3005 5.600 3000.0 1000 4 sig fig Zeros are between sig figs 5 sig fig Last zero is exact and others are in between 4 sig fig Zeros are exact zeros 3 sig fig Bar makes place holders significant

4. Rounding to Sig Figs 1 sig fig 3 sig fig 5 sig fig 7 sig fig Need the bar to make the place holder significant

5. 1.55 x 10 6 nm = km This is just a metric conversion ---- always 2 steps. 1.55 x 10 6 nm Start with what you’re given: One step to the BASE unit, meters: One step to the desired unit, kilometers: xx nm m 1x10 -9 1 1 km 1x10 3 m 1.55x10 -6 km 3 sig figs

6. .00000093 Tg =  g This is just a metric conversion ---- always 2 steps..00000093Tg Start with what you’re given: One step to the BASE unit, grams: One step to the desired unit, micrograms: xx Tg g 1x10 12 1 1 gg 1x10 -6 g 9.3x10 11  g 2 sig figs

7. 8.5 x 10 -20 Ml = ml This is just a metric conversion ---- always 2 steps. 8.5 x10 -20 Ml Start with what you’re given: One step to the BASE unit, liters: One step to the desired unit, milliliters: xx Ml l 1x10 6 1 1 ml 1x10 -3 l 8.5x10 -11 ml Or you could use this for last fraction  1000 ml 1 l 2 sig figs

8. 8 gallons = liters Gallons is an English unit and liters is a metric unit - determine what Metric-English conversion will work (from box at top of homework) 8 gal Start with what you’re given: xx gal qt 4 1.94 l 1qt 30.08 liters 1 sig figs 30 liters

9. 5.75 x 10 15 s = years 5.75 x10 15 s Start with what you’re given: Keep converting to bigger units of time until you get to years: x x s min1 60 1 hr 60 min 1.82x10 8 yr x x 1 1 daysyr hr days 24 365 3 sig figs

10. 500 ml/min = qt/hr This has 2 dimensions. Convert ml to qt and min to hr Start with what you’re given: ml is on top Min on bottom x ml l 1x10 -3 1 1 qt hr 31.9 qt/hr xx 500 ml min.94l 60 min 1 1 sig figs 30 qt/hr

11. 9 in 2 = cm 2 9 in 2 Start with what you’re given: Need 2 factors of inches to cancel inches squared x in cm 2.54 1 x cm 1in 58.06 cm 2 1 sig figs 60 cm 2