7. What volume does a sample of 1.5 x 1023 atoms of helium at STP represent? a) 5.6 liters b) 11.2 liters c) 17.8 liters d) 22.4 liters

a) 5.6 L

Explanation:

Step 1: Given data

Atoms of helium: 1.5 × 10²³ atoms

Conditions: Standard temperature (273.15 K) and pressure (1 atm)

Step 2: Calculate the moles corresponding to 1.5 × 10²³ atoms

To convert atoms to moles, we will use Avogadro's number: there are 6.02 × 10²³ atoms of helium in 1 mole of atoms of helium.

1.5 × 10²³ atoms × 1 mol/6.02 × 10²³ atoms = 0.25 mol

Step 3: Calculate the volume of 0.25 moles of He at STP

At STP, 1 mole of helium occupies 22.4 L.

0.25 mol × 22.4 L/1 mol = 5.6 L

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.