Game of Periodicity

STACK-1

100

Which statement describes the trend in atomic radius across Period 3?

1. Increases

2. Decreases

3. Remains the same

4. Increases then decreases

2. Decreases

Atomic radius decreases across Period 3 due to increasing nuclear charge, pulling electrons closer.

200

Which Period 3 oxide reacts with water to give a solution with pH

~13?

1. SiO2

2. P4O10

3. Na2O

4. SO2

Correct Answer: c) Na2O

Na2O + H2O             2NaOH, a strong base, yielding pH ~13.

300

The reaction of NaCl with water produces a solution with pH:

1. Acidic

2. Neutral

3. Strongly acidic

4. Basic

Correct Answer: b) Neutral

NaCl dissolves to form Na+ and Cl–, which do not affect pH.

400

Which Period 3 chloride has a simple molecular structure?

1. NaCl

2. AlCl3

3. MgCl2

4. Non

Correct Answer: b) AlCl3

AlCl3 forms a dimeric Al2Cl6 with a simple molecular structure in vapor.

500

The chloride of which element sublimes easily and hydrolyses in water?

1. NaCl

2. AlCl3

3. MgCl2

4. None

Correct Answer: b) AlCl3

AlCl3 sublimes and hydrolyzes to form HCl and Al(OH)3.

STACK-2

100

Which element in Period 3 has the smallest atomic radius?

1. Sodium

2. Magnesium

3. Silicon

4. Argon

 4. Argon

Argon has the smallest atomic radius due to its high nuclear charge and no additional electron shells.

200

What causes the decrease in atomic radius across Period 3?

1. Increased shielding

2. Decreased nuclear charge

3. Increased nuclear charge

4. Increased electron-electron repulsion

Correct Answer: c) Increased nuclear charge

More protons increase nuclear attraction, reducing atomic radius.

300

The oxidation state of phosphorus in PCl₅ is:

a) +3

b) +5

3. 0

4. -3

Correct Answer: b) +5

Chlorine is -1; phosphorus is +5 to balance PCl5.

400

Which Period 3 element does not form a stable chloride?

1. Phosphorus

2. Silicon

3. Sulfur

4. Aluminium

Correct Answer: c) Sulfur

Sulfur does not form a stable chloride due to its bonding preferences.

500

The melting point of sulfur is low because it has:

1. Ionic bonds

2. Giant covalent structure

3. Simple molecular structure

4. Metallic bonding

Correct Answer: c) Simple molecular structure

Sulfur (S8) has weak van der Waals forces, lowering its melting point

STACK-3

100

Which element in Period 3 has the highest melting point?

1. Silicon

2. Sodium

3. Sulfur

4. Aluminium

Correct Answer: 1. Silicon

Silicons covalent network structure requires significant energy to break.

200

Which chloride hydrolyses completely in water to give a strongly acidic solution?

1. NaCl

2. MgCl2

3. SiCl4

4. AlCl3

Correct Answer: c) SiCl4

SiCl4 + 4H2O -->    Si(OH)4 + 4HCl, producing a strongly acidic solution.

300

Which element in Period 3 forms a chloride that fumes in moist air due to hydrolysis?

1. Na

2. Mg

3. Al

4. Ar

Correct Answer: c) Al

AlCl3 hydrolyzes to produce HCl fumes: 

AlCl₃ + 3H₂O --> Al(OH)₃ + 3HCl.

400

Which element in Period 3 has the highest first ionisation energy?

1. Na

2. Mg

3. Cl

4. Ar

Correct Answer: d) Ar

Argons full valence shell results in the highest ionisation energy.

500

Which statement is true for Na and Mg reacting with water?

1. Both react violently

2. Only Na reacts

3. Only Mg reacts

4. Neither reacts

Correct Answer: b) Only Na reacts

Sodium reacts vigorously; magnesium reacts very slowly with water.

STACK-4

100

What type of bonding is present in SiO₂?

1. Ionic

2. Simple molecular

3. Giant covalent

4. Metallic

Correct Answer: 3. Giant covalent

SiO2 forms a giant covalent lattice with strong Si-O bonds.

200

What is the oxidation state of sulfur in SO2?

1. +2

2. +4

3. +6

4. 0

Correct Answer: b) +4

Oxygen is -2; sulfur is +4 to balance SO2.

300

What is the pH of the solution formed when SO2 dissolves in water?

1. Around 1

2. Around 3

3. Around 7

4. Around 10

Correct Answer: b) Around 3

SO2 + H2O --> H2SO3, a weak acid, yields pH ~3.

400

The melting point of phosphorus is lower than silicon because:

1. Phosphorus has simple molecular structure

2. Phosphorus is more reactive

3. Silicon has a lower atomic radius

4. Phosphorus has giant covalent structure

Correct Answer: a) Phosphorus has simple molecular structure

Phosphorus (P4) has weak intermolecular forces, unlike silicons covalent network.

500

The pH of the solution formed when P4O10 reacts with water is:

1. Around 14

2. Around 7

3. Around 1

4. Around 9

Correct Answer: c) Around 1

P4O10 + 6H2O --> 4H3PO4, a strong acid, yields pH ~1.

STACK-5

100

Which Period 3 element forms an oxide that is amphoteric?

1. Sodium

2. Magnesium

3. Aluminium

4. Silicon

Correct Answer: 3. Aluminium

Al2O3 reacts with both acids and bases, showing amphoteric behavior.

200

Which statement is true about electrical conductivity across Period 3?

1. Increases across the period

2. Decreases uniformly

3. Increases then decreases

4. Remains constan

Correct Answer: c) Increases then decreases

Conductivity peaks at aluminum due to metallic bonding, then drops for non-metals.

300

The oxide formed when phosphorus reacts with oxygen is:

1. P₄O₆

2. P₄O₁₀

3. PO

4. P₂O₅

Correct Answer: b) P₄O₁₀

Phosphorus forms P4 + 5O2--> P4O10

400

Which oxide of Period 3 behaves as a base with acids?

1. SO2

2. SO3

3. MgO

4. P4O10

Correct Answer: c) MgO

MgO reacts with acids to form salts, acting as a base.

500

Which Period 3 oxide does not dissolve in water but reacts with acids and bases?

1. SiO2

2. P4O10

3. SO2

4. Na2O

Correct Answer: a) SiO2

SiO2 is insoluble but reacts with strong bases and acids like HF.