An unknown substance has a volume of 2 cm and a mass of 38.6 grams what is the density

You are suppose to put one!

The gas in the piston is being heated, and the piston has moved upward. The observation will be summarized in a row of the incomplete table below.

The doctor knows that people taking the medicine may sleep better just because they expect the medicine to work. How can he be sure of whether the medicine really works?

How much heat is given off when 869 g iron bar cools from 94 degrees celsius to 5 degrees celsius? * c of Fe is 0.444 J/g*celsius? How much heat is given oft when 869 iron bar col from 94 degrees celsius to 5

The atomics number of nitrogen is 7. how many protons, neutrons, and electrons make up an atom of nitrogen-15?

How many liters of chlorine gas can be produced when 0.98 l of hcl react with excess o2 at stp? 4hcl (g) + o2 (g) - > 2cl2 (g) + 2h2o (g) ?

In the reaction of 1.15 g of salicylic acid, molar mass 138.12 g/mol, with 2.83 g of acetic anhydride, molar mass 102.10 g/mol, a student obtained 1.21 g of acetylsalicylic acid, molar mass 180.17 g/mol. What is the percent yield?

A sample of hydrated calcium sulfate has a mass of 20.88 g. After it is heated, it has a mass of 16.51 g. What is the percentage by mass of water in the hydrate

All organisms need energy from food in order to survive. Plants produce their own food through photosynthesis. Animals must find external sources for food. Which of the following is true? A. Plants are autotrophs, and animals are heterotrophs. B.

What is effective nuclear charge of S2 - and S? Does the Zeff differs from ions and atoms of the same element.