Principles of Chemistry

What is empirical formula?

• True formula

• Smallest whole-number ratio of atoms present in a molecule

• Total number of atoms present in one molecule

• All of the above

The number of electrons for an ion A^2-, is 18. Calculate the number of proton in the ion.

• 16

• 18

• 20

• 22

Tags

NGSS.MS-PS1-1

X²⁺ and Y^2- have the same number of electrons as Neon atom. Identify the element X and Y.

• X = Aluminium, Y = Sulphur

• X = Magnesium, Y = Oxygen

• X = Aluminium, Y = Oxygen

• X = Magnesium, Y = Sulphur

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

The number of atoms present in HCOOH was found to be 1.736 × 10²⁵.Determine the mass of HCOOH.

• 265.38 g

• 7.98 g

• 1326.76 g

• 28.83 g

Salicylic acid is a pain reliever which consists of 6.558 g of carbon atoms, 0.471 g of hydrogen atoms and 3.744 g of oxygen atoms. Determine the empirical formula of salicylic

acid.

• C₈H₁₂O₃

• C₇H₆O₃

• C₈H₅O₃

• C₃H₂O

Tags

NGSS.HS-PS1-2

NGSS.HS-PS1-7

Calculate the number of atoms in 1 g of He.

• 1.5 x 10²³

• 0.25

• 4

• 4.15 x 10^-25

Calculate the number of electrons in 0.1 mol Na. (Z = 11)

• 6.02 x 10²³

• 6.6 x 10²³

• 1.7 x 10^-25

• 1.8 x 10^-24

What is the oxidation number of Cl i Cl₂O₇?

• -1

• -5

• +5

• +7

What is the ratio of proton/neutron in mercury, ²⁰⁰Hg? (Z=80)

• 3:2

• 2:3

• 1:2

• 4:5

The molecular weight of phosphorus oxide is 283.886 g/mol. Determinethe molecular formula of the phosphorus oxide if the empirical formula is P₂O₅.

• P₆O₁₅

• P₈O₂₀

• P₄O₁₀

• P₁₀O₂₅