4N ScChem TYS MCQ Topic 11 - Periodic Table

The positions of two elements iodine, I, and chlorine, Cl, in the Periodic Table are shown.

How do colours and melting points of iodine and chlorine compare?

• A

• B

• C

• D

Answer explanation

Down Group VII, the colours of halogens become darker and melting points increase.

Thus, chlorine (greenish yellow) has lighter colour than iodine (purplish black), and iodine has higher melting point than chlorine.

Which statement about the element with relative atomic mass 16 is correct?

• It forms ions with a charge of 3-.

• It has 8 electrons in its outer shell.

• It has 8 protons in its nucleus.

• It is a metallic element.

Answer explanation

The element with relative atomic mass 16 is oxygen.

Option A is wrong: oxygen forms ions with charge of 2-, not 3-.

Option B is wrong: oxygen has 6 outer electrons, not 8.

Option C is correct.

Option D is wrong: oxygen is a non-metal.

The table shows some properties of two elements in Group 17 of the Periodic Table.

What are the properties of fluorine?

• A

• B

• C

• D

Answer explanation

Down Group VII:

• - melting and boiling points increase, hence fluorine has a lower melting point (-220 ^oC) than chlorine, and exists as a gas at 20 ^oC

- fluorine has lower density (0.0017 g/cm³) than chlorine

Beryllium, magnesium and calcium are all in the same group of the Periodic Table.

Which statement about these elements is correct?

• They all have the same number of electrons in their atoms.

• They all have the same number of electrons in their outer shell.

• They all have the same number of protons in their atoms.

• They all have the same total number of protons plus neutrons in the nuclei of their atoms.

Answer explanation

Elements in the same group have the same number of electrons in the outer shell.

Group II elements have two outer electrons.

Three elements each have two valency electrons.

Which statement about the elements is correct?

• They are all metallic and belong to the same group of the Periodic Table.

• They are all metallic but belong to different groups of the Periodic Table.

• They are all non-metallic and belong to the same group of the Periodic Table.

• They are all non-metallic but belong to different groups of the Periodic Table.

Answer explanation

Elements in the same group have same number of outer electrons.

Group II elements have two outer electrons and are metallic.

Elements X, Y and Z are in Group 17 of the Periodic Table.

X is a gas.

Y is less reactive than Z.

Z is a red liquid.

X, Y and Z are placed in order of increasing proton number.

Which order is correct?

Answer explanation

Down Group VII:

• (1) melting and boiling points increase.

Z (liquid) is likely to be below X (gas).

• (2) chemical reactivity of Group VII elements decreases

Y is below Z as it

is less reactive than Z.

How are the elements arranged in the Periodic Table?

• in order of chemical reactivity

• in order of electron shells

• in order of proton number

• in order of relative atomic mass

Answer explanation

Elements in the Periodic Table are arranged in order of increasing atomic number (also called proton number).

Which determines the group of an element in the Periodic Table?

• the number of completely filled electron shells

• the number of electrons in the shell closest to the nucleus

• the number of electrons in the shell furthest from the nucleus

• the number of protons in the nucleus

Answer explanation

Elements in the same group have the same number of valence electrons, which is the number of electrons in the outermost shell (furthest away from the nucleus).

Which compound contains three different non-metallic elements?

• C₂H₅Cl

• LiBH₄

• SeO₂

• Si₂H₆

Answer explanation

Option A is correct:

C₂H₅Cl contains 3 different non-metallic elements (C, H and Cl).

Option B is wrong:

LiBH₄ contains 1 metallic element (Li) and 2 different non-metallic elements (B and H).

Option C is wrong:

SeO₂ contains 2 non-metallic elements (Se and O).

Option D is wrong:

Si₂H₆ contains 2 non-metallic elements (Si and H).

The diagram shows part of the Periodic Table of the Elements.

Which statement about the proton (atomic) number of X is correct?

• It is one less than that of Y.

• It is sixteen less than that of Y.

• It is three less than that of Z.

• It is seven less than that of Z.

Answer explanation

Based on the positions of X, Y and Z in the Periodic Table:

X has electronic configuration of 2,4. Hence X has 6 protons.

Y has electronic configuration of 2,8,4. Hence Y has 14 protons.

Z has electronic configuration of 2,7. Hence Z has 9 protons.

Hence, proton number of X is three less than that of Z.