What is the definition of Avogadro’s number?The number of particles in one mole of a substanceThe number of particles in one gram of a substanceThe number of moles in one gram of a substanceThe number of grams in one mole of a substance2Which of the following is the best definition for one mole of any substance?Has the same mass as the Mr of that substanceIs expressed in gramsContains 6×1023 particlesContains 6×1023 particles and has the same mass in grams as the Mr of that substance3What is the mass of one mole of fluorine gas?38 g19 g18 g9 g4How many moles are there in 54 g of water?42315Five moles of an unknown element have a mass of 35 g. What is the element?OxygenLithiumSodiumCarbon

Avogadro's number is defined as the number of particles in one mole of a substance. This is approximately 6.022 x 10^23 particles.

The best definition for one mole of any substance is that it contains 6×10^23 particles and has the same mass in grams as the molar mass (Mr) of that substance.

The mass of one mole of fluorine gas is 38 g. This is because the atomic mass of fluorine is 19, and since fluorine gas is diatomic (F2), its molar mass is 19*2 = 38 g.

The number of moles in 54 g of water can be calculated using the formula: moles = mass/molar mass. The molar mass of water (H2O) is approximately 18 g/mol. So, 54 g of water is 54/18 = 3 moles.

If five moles of an unknown element have a mass of 35 g, the molar mass of the element is 35/5 = 7 g/mol. The element with a molar mass closest to this is lithium (Li), with a molar mass of approximately 6.94 g/mol. Therefore, the unknown element is likely lithium.