How many valence electrons are present in zinc?

The chart shows the bid provided by four contractors to complete a job. which contractor is the most cost-effective?

If a molecule with a molecular formula of c13h18 is treated with an excess of h2 in the presence of finally divided pt metal under conditions required for maximum hydrogenation of the molecule to give a molecule with a formula c13h24, how many rings are in the molecule?

At stp, which substance is the best conductor of electricity? a. nitrogen b. neon c. sulfur d. silver