When Mendeleev started his work on organizing the elements, about how many had

been discovered?

about 10

well over 100

about 60

the same as today

Chromatography Portfolio 5. What evidence is there that marker ink is a mixture? 6. Each compound in the marker ink is represented by a color. Did one compound travel farther than others? Explain why you think that this is the case. 7.

Some chemical hazards are physical and some are related to the potential health effects of exposure. Click only one box for each response Toxicity Carcinogenic Flames Inhalation hazard Flying objects

2When are ratios useful? Choose the best answer.

Properties of alloy

Convert 2.57 x 10 10 atoms of Cr to moles

Light from the sun is absorbed by the ground and converted to what?

What contains paired statements that can be used to identify orgainisms

The molecule below contains both an aldehyde and a ketone functional group. select only the carbonyl carbon atom of the aldehyde functional group. identify the carbon atom by selecting the atom and assigning it a map number of 1.

what is the volume of 0.98 mol oxygen (O2) gas at 275 K and a pressure of 2.0 atm? (the universal gas constant is 0.0821 L*atm/mol*K)

A student asks you for a simple rule to tell apart plants cells and animal cells when viewed under a microscope. Describe such a rule.