Ratios, SI, Scientific Notation

1. If 1 : 2 as 3 : x, then what is x?

2. If x : 4 as 3 : 1, then what is x?

3. If 1 : 3 as x : 4, then what is x?

There is a general method for solving ratio problems. The ratios must equal each other, so write each ratio as a fraction and make them equal. (Keep the x on the top to keep it simple, and don’t get them out of order.) E.g. for (1) above,
3 : x becomes x/3, and 1 : 2 becomes 2/1.

Then equate the fractions and solve for x.

x/3 = 2/1, so x = 2/1 * 3 = 6.

Repeat the above problems using this method:

i x/3 = 2/1 so x = ?

ii x/4 = 3/1 so x = ?

iii x /4 =1/3 so x = ?

4. If x : 2 goes as 3 × 106 : 6× 105then what is x?

5. If a roller coaster causes 2 vomits in each car, then how many vomits happen in 4 cars. (Write the ratios first.)

6. If 3 mips generates 0.18 pls, then how many mips are required if 36 pls are required. (Write the ratios first.)

7. If 1 mole equals6.02atoms, then 3.01 atoms corresponds to how many moles.

8. If 1 mole of a gas has a volume of 22.4L, then how many moles are there is 100L of gas.

9. One mole of carbon has a mass of 12g. How many moles of carbon are present in 1.2×101 kg of carbon.

10. 1 mole of H2 has a mass of 2×10-3 kg. A balloon holding 6.82 ×10-3moles will contain what mass of H2.

11. If 2.3×10-4moles of Zinc has a mass of 1.50×10-2g, then what is the mass of 1 mole of zinc.

Answers: (1) 6 (2) 12 (3) 4/3 (4) 10 (5) 8
(6) 600 mips (7) 5 × 10-4 moles (8) 4.46 moles
(9) 1000 moles (10) 0.01364g (11) 65.22g