Choose the letter of the choice that best completes the statement or answers the question.

Which of the elements listed below is a metal with 2 valence electrons?

a.

magnesium

c.

platinum

b.

uranium

d.

chlorine

28.0 grams of sodium are how many moles?

What is a substance that by its presence increases the speed of a chemical reaction between other substances and yet is itself unchanged by the reaction? a. accelerator b. catalyst c. inducement d. reactor

How can you determine if covalent bonding will occur?

Using a balanced chemical reaction and a periodic table, which of the following is not possible to calculate? a. the molar mass of the products b. the number of atoms in the reaction c. the number of molecules in the reaction d.

How are rubies, emeralds, and sapphires formed?

Be sure to answer all parts. Which product (s) form (s) at each electrode in the aqueous electrolysis of the following salts? Select as many as apply.

True or false. elements in the same period have the same number of valence electrons

A base a. causes phenolphthalein indicator to change from colorless to pink. b. donates a proton in a proton transfer reaction. c. accepts electrons in an electron transfer reaction. d. produces hydrogen ions in solution. e. does none of the above.

Which of these is an indicator that a chemical reaction has occurred? precipitate forms temperature remains the same color is diluted mass increases

The half-life of isotope X is 3 days, how long will it take for one half of 10g sample to decay