Elements in the same group (family) appeared to have the same what?     a) valence. b) melting point. c) isotopic ratio. d) number of neutrons.

Urea, co(nh2)2, is manufactured on a large scale for use in producing urea-formaldehyde plastics and as a fertilizer. what is the maximum mass of urea that can be manufactured from the co2 produced by combustion of 1.00 x 104 grams of co2?

Which of the following has wavelength longer than the wavelength of viable light? a) x rays b) gamma rays c) radios waves d) ultraviolet waves

Astudent pours 10.0 g of salt into a container of water and observes the amount of time it takes for the salt to dissolve. she then repeats the process using the same amounts of salt and water but this time she slowly stirs the mixture while it is dissolving. the student performs the experiment one more time but this time she stirs the mixture rapidly. the dependent variable in this experiment is: time for salt to dissolve speed of stirring amount of water mass of salt