1. only one. leading zeros are never significant

2. 5, captive(sanwiched zeros) are always good

3. 1 only; trailing zeros are only good when ther's a decimal

4. 3

5. I don't know where the (a) went!

b) 22.1 ^oC

c) 0.0 ^oC ; you need to hav ethe same number of decimals for the same intrument used in the measurement

Problems

1. V₁ /(37+273) = 3.7 V₁/(x + 273)

x = 874 = 870 ^oC or 8.7 X 10 ^{2 o}C. (two SF becuase of the 3.7)

2. 12.011 + 15.9994 = 28.010 amu or g/mole (3 decimal places becuase when adding the answer must have as many decimal places as the measurement with the least number)

3. V₁/T₁ = V₂/T₂

For 1 mole:

22.4/273 = V₂/(25+273)

V₂ = 24.4512 L (don't apply SF rules yet)

d = m/V = 32g/24.4512 L = 1.3 g/L (two sf becuase of 25 ^oC and 32 g/mole)

or first calculate n/V = P/RT and then multiply by molar mass = 1.3 g/L

Flashback:

a) Under very high pressure; or under low temperatures. In each case there would be more attractions, which would make it lose ideal behaviour.

a)