Which of the following is an example of a pure substance?

Consider the following data obtained by decomposing samples of carbon dioxide, CO₂, into its component elements.

Mass of CO₂ and Components

Sample	Mass CO2	Mass C	Mass O2
1	44.00 g	12.00 g	32.00 g
2	22.00 g	6.00 g	16.00 g
3	88.00 g	24.00 g	64.00 g

Which of the following statements is consistent with this data?

Atoms __________ .

Which of the following statements is a hypothesis about the synthesis of gold nanoparticles? (LO 1.1) (a) Adding a salt solution to gold nanoparticles causes the color to change from red to blue.(b) To examine the effect of salt on gold nanoparticles, variable concentrations of salt are added to the nanopar-ticles and the results are measured(c) A solution of gold nanoparticles with an average diam-eter of 30 nm has a wavelength of maximum absorption of 450 nm and is a reddish-orange color.(d) Adding a substance with a negative charge to the surface of the nanoparticles creates repulsive forces that stabilize small particle size