# Quiz | The periodic table and Chemical Periodicity

1

How many atoms of hydrogen do you have in 2.0 moles of H2?

6.0 x 1023 atoms

1.2 x 1024 atoms

2.4 x 1024 atoms

We need the mass to answer this question

n = $\frac{\mathrm{N}}{{\mathrm{N}}_{\mathrm{A}}}$   ⇒   number of dihydrogen atoms ${\mathrm{N}}_{{\mathrm{H}}_{2}}$ = ${\mathrm{n}}_{{\mathrm{H}}_{2}}$ x NA = 2.0 x 6.022 x 1023 atoms

⇒ number of hydrogen atoms ${\mathrm{N}}_{\mathrm{H}}$ = 2 x ${\mathrm{N}}_{{\mathrm{H}}_{2}}$

2

What is the SI unit of molar mass?

g

g.mol-1

mol

no unit

The SI unit of molar mass M is g.mol-1

3

What is the mole number of 12.4 g of MgCl2 (MMg = 24.3 g.mol-1, MCl = 35.5 g.mol-1)?

1.30 x 10-2 mol

0.130

0.207

1.18 x 103 mol

mole number ${\mathrm{n}}_{{\mathrm{MgCl}}_{2}}$ = $\frac{{\mathrm{m}}_{{\mathrm{MgCl}}_{2}}}{{\mathrm{M}}_{{\mathrm{MgCl}}_{2}}}$

with MMgCl2 = MMg + 2 x MCl = 95.3 g.mol-1

4

What is the empirical formula of CH3CH2CH2O-O-CH2CH2CH3?

C3H7O

C6H14O2

(CH3CH2CH2O)2

CH3(CH2)2O2(CH2)2CH3

Empirical formula = the simplest whole-number ratio of atoms in a compound

5

Which of the following statements is incorrect?

Halogens are colorful and corrosive nonmetals and are diatomic molecules in nature

Noble gases are the last group of the periodic table and are inert gases

Alkali metals form the first group of the periodic table while alkaline-earth metals form the second

None of the above

6

What is the second period in the periodic table?

Li, Be, B, C, N, O, F, Ne

Be, Mg, Ca, Sr, Ba, Ra

Na, Mg, Al, Si, P, S, Cl, Ar

F, Cl, Br, I, At