1. Precise measurements are all about the same. 2. In the number 6.300 the zeros aren’t significant.
3. To change a material from liquid to gas we need to increase its temperature.
4. Melting is the phase change from liquid to gas.
5. Water, without salt in it, is accurately described as pure.
6. Pure elements contain atoms of different atomic numbers.
7. 1 gram is equal to 1000 milligrams.
8. 1 gram of water has a volume of 1 cm3 meaning water has a density of 1 g/cm3.
9. Solutions can be filtered to separate the parts present.
10. The combination of materials with different properties is a mixture.

Sum of brother and sisters age is 26. four times the brothers age is subtracted from three times the sisters age, the difference is 8. what are the ages of the brother and sister?

Select the correct value for the indicated bond angle in each of the compounds. o−o−oo−o−o angle of o3 90° 109.5° < 109.5° 120° < 120° 180° f−b−ff−b−f angle of bf3 180° < 109.5° < 120° 120° 109.5° 90° f−o−ff−o−f angle of of2 < 120° 120° 90° 109.5° 180° < 109.5° cl−be−clcl−be−cl angle of becl2 90° 109.5° 180° 120° < 109.5° < 120° f−p−ff−p−f angle of pf3 90° 109.5° < 109.5° 180° 120° < 120° h−c−hh−c−h angle of ch4 90° < 109.5° 180° 120° < 120° 109.5°

Gusing the milligrams of ascorbic acid you entered above, the ratio of total sample volume to aliquot volume, and the total milligrams of the vitamin c tablet that you dissolved, calculate the mass of ascorbic acid in the vitamin c tablet for each trial. do this by scaling up to find the amount (mg) of ascorbic acid in your 250 ml flask. enter your calculated mass of ascorbic acid in the vitamin c tablet, for each trial. be sure to enter your calculated mass in the corresponding order that you entered your milligrams of ascorbic acid. the milligrams of ascorbic acid you entered for entry #1 previously should correspond to the mass of ascorbic acid that you enter for entry #1 here.