At room temperature and pressure, classify each of the following macroscopic samples as solid, liquid or gas: salt water nitrogen O In the following descriptions the particles are atoms, molecules, or ions. To which sample above does each description best apply? The particles are in close contact and are held in place. The spaces between the particles is the largest. 0 O

Hydrogen peroxide (H2O2) is a mild antiseptic used to prevent infection in minor cuts and scrapes. The density of H2O2 is 1.45 g/mL. The cylinder container that the hydrogen peroxide is stored in has a radius of 8.5 cm and a height of 22 cm. If the container is full, calculate the number of oxygen atoms in the container. (Vcylinder = πr2h).

A hypothetical metal has a theoretical density of 11.47 g/cm3. This metal adopts a cubic crystal structure with an edge length of 0.387 nm and atomic radius of 0.137 nm. Find the atomic weight of this metal in g/mol. NA = 6.022 x 1023 atoms/mol. Express your answer in two decimal places only. Do not put the units.

How many grams of oxygen (O) are present in a 6.41 g sample of potassium nitrate (KNO3)? Enter your answer in decimal form with the correct number of sig figs. Use the proper abbreviation for the units. NOTE:  If you have taken chemistry before and know what diatomic means, do not take that into consideration.  Use just O for this.  There are reasons for this.

Tia has a sample of pure gold (Au). She weighed the sample and the result was 84.784.7 grams. Tia wants to determine the number of atoms in the sample. Calculate the number of atoms in 84.784.7 g of pure gold.

An analytical chemist measures the amount of Elements E₁ and E₂ in four samples of an unknown Substance. sample of E1 1 2 3 mass mass of E2 4 16.0 g 9.1 g 17.1 g 9.8 g 18.5 g 10.6 g 12.0 g 6.9 g It's known that X contains no elements other than E₁ and E₂. Using this information, answer the questions in the table below. Is X a pure substance or a mixture? If you don't have enough information to decide, choose can't decide. If you said X is a pure substance, calculate the mass of Element E₁ the analytical chemist would find in a new 10.0 g sample of X. Round your answer to 2 significant digits. O pure substance O mixture O (can't decide) g

Which statement is FALSE? O A pure substance can be varied by changing the proportion of pure substances making it up A mixture can be separated into 2 or more substances by physical or mechanical means A pure substance had properties that are constant, no matter where you find it A pure substance has constant chemical composition A mixture's composition can be varied by changing the proportion of pure substances making it up

How many moles are there in 1.0 g of the element Al? Your answer must contain the correct number of significant figures. 13 6.022 x 10^23 0.037 4 x 10^-2 1.0

Calculate the number of boron atoms in a 120.0 g sample of tetraborane (B4H10). Be sure your answer has a unit symbol if necessary, and round it to 4 significant digits. 0 ☐x10 X Ś

The radius of a potassium atom is 231 pm. How many potassium atoms would have to be laid side by side to span a distance of 4.87 mm? atoms