How many number of molecules and atoms respectively are present in 2.8 litres of a diatomic gas at STP?

Sure, let's solve this step by step.

1. At Standard Temperature and Pressure (STP), one mole of any gas occupies 22.4 litres.

2. So, the number of moles of the gas in 2.8 litres can be calculated as follows: Number of moles = Volume of gas at STP / Volume of one mole of gas at STP Number of moles = 2.8 litres / 22.4 litres per mole = 0.125 moles

3. Avogadro's law states that one mole of any substance contains 6.022 x 10^23 entities (atoms, molecules, etc.).

4. Therefore, the number of molecules in 0.125 moles of gas can be calculated as follows: Number of molecules = Number of moles x Avogadro's number Number of molecules = 0.125 moles x 6.022 x 10^23 molecules per mole = 7.5275 x 10^22 molecules

5. Since the gas is diatomic, each molecule is composed of two atoms.

6. Therefore, the number of atoms in the gas can be calculated as follows: Number of atoms = Number of molecules x Number of atoms per molecule Number of atoms = 7.5275 x 10^22 molecules x 2 atoms per molecule = 1.5055 x 10^23 atoms

So, there are approximately 7.53 x 10^22 molecules and 1.51 x 10^23 atoms in 2.8 litres of a diatomic gas at STP.