What do parentheses around a group of atoms in a chemical formula indicate?

Geologists think that parts of the Appalachian Mountains formed originally from sediments accumulating in shallow swamps. The weight of the sediments caused the area beneath them to sink, allowing more sediments to accumulate.

The wavelength of light in the infrared region is 4.257 * 10-7 cm. What is the frequency of this light?

There are six continents on Earth. True False

Bonsoir les amis, demain j'ai un examen de chimie en solution et je veux bien que vous m'aider à faire ce exercice s'il vous plait calculer la qantite de NACL et de l'eau nécessaire pour l'obtention de 250g solution de NACL avec le pourcentage

Cation and anion of Cr (CO3) 3

How many grams of the excess reactant remain assuming the reaction goes to completion and that you start with 15.5g of na2s and 12.1g cuso4?

Which elements can be found in the sun? a. hydrogen and oxygen b. helium and oxygen c. hydrogen and helium d. hydrogen and nitrogen?

A sample of hydrogen gas at 2.0 atmospheres and 273 k occupies a volume of 5.0 liters. the gas sample is completely transferred to a 10.0-liter sealed, rigid container.

To make sure that the white powder was all sodium chloride and not mixed with sodium hydrogen carbonate, would you need to add a little less or a little more hydrochloric acid to the reaction?

A 10.0 gram sample of h2o at 23.0c absorbs 209 joules of heat. what is the final temperature