The concentration of lead ion in a water sample is 5ppb. Calculate the amount of lead ion in 2000g of this water sample?

10 μg or 1 x 10⁻⁵ g

Explanation:

The concentration of lead ion is given in parts by billion (ppb), which means that there are 5 micrograms (μg) of lead in 1 liter of water sample:

5 ppb = 5 μg lead ion/L

If we assume that the density of the water sample is equal to 1 g/ml (density of water at 25°C), we can say that 2000 g of sample is equal to 2000 mL:

sample volume = 2000 g x 1 mL/g = 2000 mL x 1 L/1000 mL = 2 L

Thus, the amount of lead ion in 2000 g (or 2 L) of water sample is:

mass of lead ion = 5 μg lead/L x 2 L = 10 μg x 1 g/10⁶μg = 1 x 10⁻⁵ g

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e