Health, 17.10.2020 15:01 mauricestepenson791
A student is given two mineral samples that appear very similar. They both are opaque, white, and shiny. He knows that they are either calcite or quartz. To determine the identity of each mineral, the student puts a couple of drops of hydrochloric acid (HCl) on each sample. When calcite reacts with hydrochloric acid, carbon dioxide gas is produced. When HCl is placed on quartz, no changes are observed. Based on the information above, what evidence indicates that a chemical reaction occurs when HCl is placed on calcite?
Answers: 1
Health, 22.06.2019 15:20, timozy95
[120 total points] (public health) in one of the largest human experiments ever conducted, in 1954 a randomized controlled trial was run to see whether a vaccine developed by a doctor named jonas salk was effective in preventing paralytic polio. a total of 401,974 children (ages 6–9), chosen to be representative of those who might be susceptible to the disease, were randomized to two groups: 200,745 children (the control group c) were injected with a harmless saline solution (a placebo) and the other 201,229 children (the treatment group t) were injected with salk’s vaccine. what was the point of giving saline solution to the children who didn’t get the vaccine? explain briefly.
Answers: 2
Health, 23.06.2019 00:30, ryanbransky
Health and cardio respiratory fitness occurs when the heart is working, at minimum, 50 percent of heart rate reserve. true or false
Answers: 2
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