Calculate the mass in grams of 1.72×10^24 molecules of formaldehyde. The chemical formula for formaldehyde is CH2O.

m= 85.8 g CH2O

Explanation: First step is convert the molecules of CH2O to moles using the Avogadro's Number.

1.72x10²⁴ molecules CH2O x 1 mole CH2O / 6.022x10²³ molecules CH2O

= 2.86 moles CH2O

Next is convert the moles of CH2O to mass using the molar mass of CH2O

2.86 moles CH2O x 30 g CH2O / 1 mole CH2O

= 85.8 g CH2O

- decrease the number of plants and animals living in the water.

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3