234+34.1 add and round to 2 significant figures

In a five-fold serial dilution of a 20 pg/ml solution, all tube dilutions are 1/5. What is the substance concentration in the third tube of this series?

The lion's scientific name is Panthera leo. The leopard's scientific name is Panthera pardus. The tiger's is Panthera tigris. Which statement is true?

In the reaction, Zn + HCl-> ZnCl2 + H2, 25 grams Zn are reacted with 17.5 grams HCl. How many grams of H2 will be produced? A. 0.382 g of H2 B. 0.479 g of H2 C. 0.7865 g of H2 D. 0.484 g of H2

What is the oxidation number of the chloride ion in HClO?

Oxygen (O2) and nitrogen (N2) do not have much greenhouse effect, but several trace gases including carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and various chlorofluorocarbons are important greenhouse gases.

When the Sun is in its maximum solar cycle, which of the following occurs? A. One CME is produced every five days B. There is an unpredictable amount of energy C. Up to three CMEs are created in one day D. Protons and neutrons accelerate

How many daughter cells are produced in meiosis?

Sodium chlorite - > sodium chloride + oxygen what type of chemical reaction is represented by this equation

The mixing of which pair of reactants will result in a precipitation reaction? the mixing of which pair of reactants will result in a precipitation reaction?

A balloon has 18.9 moles of hydrogen gas at a volume of 428 L. What would the volume of the gas be if the balloon had 14.0 moles of hydrogen gas left after 1 day?