A change in the properties of matter that does not change the makeup of the substance is

a chemical change

a physical change

a nuclear change

a covalent change

The composition of dry air at sea level is 78.03% N2, 20.99% O2, and 0.033% CO2 by volume. (a) calculate the average molar mass of this air sample (b) calculate the partial pressures of N2, O2, and CO2 in atm.

In the hospital, 35 babies were born. If 22 were boys, what percentage was boys. Express your answer in places

The philosopher's stone weighs 43.2 g is placed in a graduated cylinder containing 63 ml of water. after the stone is added to the cylinder the water rises to 74 ml. what is the density of the stone? express your answer in g/ml.

The density of the hydrocarbon in part (a) is 2.0 g l-1 at 50°c and 0.948atm. (i) calculate the molar mass of the hydrocarbon. (ii) determine the molecular formula of the hydrocarbon.

Write the acid-base reaction that occurs when an aqueous solution of HCl is added to an aqueous solution of NaOH. (Use the lowest possible coefficients. Omit states-of-matter in your answer.

Which of the following is not a chemical reaction a) gas formation b) solid formation c) energy change d) state change

How many moles of copper are needed to react with sulfur to produce 0.25 moles Ol copper (1) sulfide according to the following reaction: 2 Cu + S + Cuzs

If you wish to warm 52 kg of water by 22 ∘c for your bath, find what the quantity of heat is needed. express your answer in calories cal.

Which of the following compounds is the most soluble in water? a) propanoic acid b) propane c) propanal d) l-bromopropane

What mass of solid Na2CO3 is required to make 250.0mL of a 0.125M solution of Na2CO3?