Give the number of significant figures in this number: 40

Which statement is part of Bohr's atomic model? Electrons absorb or emit light when they change energy levels. Electrons with the highest energy are found with orbits of the smallest radius.

Using Avogadro's Number (6.02*10^23) : Calculate the number of molecules in 3.00 moles H2S. Express your answer numerically in molecules ... Calculate the number of moles of Cl atoms in 1.81*10^24 formula units of magnesium chloride, MgCl2.

Information from various sources may be used when writing a laboratory report. Which of these sources must be cited in the References section of the report? Select all that apply.

When a sample of gas is cooled, it condenses into a liquid. In which of the following ways do the molecules of the original gas sample compare with the molecules of the liquid? a. The molecules weigh less as a gas than they do as a liquid. b.

In Part 1, draw a mechanism for the reaction of butan-2-ol with sodium amide. In the box to the left, draw any necessary curved arrows. Show the products of the reaction in the box to the right.

Why do the chemical properties cycle through each period? Every eighth element starting with hydrogen restarts the transition from metal to inert gas. Elements with atomic numbers which are multiples of eight start a new period.

Which statement correctly describes the Ka of a weak acid? The Ka is large, and the equilibrium favors products. The Ka is large, and the equilibrium favors reactants. The Ka is small, and the equilibrium favors products.

True or False? The fatal 1930 incident in Muese Valley, Belgium, was associated with leakage of toxic chemicals from a former dump site.

How many moles of neon (Ne, 20.179 g/mol) are in 68.4 grams of neon

A 50.00 mL sample of groundwater is titrated with 0.0300 M EDTA. Of 12.40 mL of EDTA is required to titrate the 50.00 mL sample, what is the hardness of the groundwater in molarity and in parts per million of CaCO 3 by mass