**Problem : **
Silver has a density of 10.5 g/mL at 25 C. What is the mass of 16 mL
of silver?

**Problem : **
How many significant figures are there in the following
numbers:

a. 209.4

B. 1.74*x*10^{-}23

c. 0.00220

d. 0.087686

B: 3, All are non-zero digits

c: 3, The first three zeros just mark the decimal place, but the zero after the 2 is significant since it indicates certainty

d. 5, the zeros serve only to mark the place

**Problem : **
Please perform the necessary math and give the number with the correct
number of significant figures. Use scientific notation where
appropriate.
A. 4.632 x 2.5

B. 12.443 +1.94672

C. 0.0000042 x 24365

D. 5.4 x 104 x 2.3 x 102

E. (41 x 3890)/36

B. 14.390

C. 1.0

D. 1.2

E. 4.4