Sunday, October 18, 2026

Plain #1

The day’s seven targets and the closest answers in our lists, with their real values. Points are before bonuses.

Round 1 · 🪐 Planetary mean radius

Using JPL’s mean radius, what is the mean diameter of Haumea, in kilometres?

Answer

1,430 km

A diameter is twice the radius. JPL lists Haumea's mean radius as 715 km.

NASA JPL Solar System Dynamics · Planetary Physical Parameters

Round 2 · 🌳 Country forest area in 2023

Name a country or territory closest to 69K km².

Target 69,000 km²

Best answer

Romania

69,459 km² · 98 points · Source

Also close

Cambodia

69,506.4 km² · 98 points · Source

Also close

Ghana

69,849.2 km² · 96 points · Source

Also close

South Sudan

71,570 km² · 89 points · Source

Round 3 · ⚡ Element ionization energy · Golden Round ×2

Name a chemical element closest to 5.3 eV.

Target 5.3 eV

Best answer

Radium

5.279 eV · 99 points · Source

Also close

Barium

5.212 eV · 95 points · Source

Also close

Lithium

5.392 eV · 94 points · Source

Also close

Lutetium

5.426 eV · 93 points · Source

Round 4 · 🧱 Element density

Using its listed density, how many grams would one cubic centimetre of tungsten weigh?

Answer

19.3 g

One cubic centimetre is a cube measuring 1 cm along each edge. Tungsten's symbol is W.

NIH PubChem · Periodic Table of Elements

Round 5 · 🐾 Pokémon height

Name a Pokémon closest to 1.8 m.

Target 1.8 m

Best answer

Aerodactyl

1.8 m · 100 points · Source

Also close

Araquanid

1.8 m · 100 points · Source

Also close

Blacephalon

1.8 m · 100 points · Source

Also close

Clodsire

1.8 m · 100 points · Source

Round 6 · 🌍 Capitals: distance from Cairo

Name a capital city closest to 5.7K km.

Target 5,700 km

Best answer

Colombo

5,679 km · 99 points · Source

Also close

Thimphu

5,630 km · 96 points · Source

Also close

Praia

5,815 km · 94 points · Source

Also close

Antananarivo

5,832 km · 93 points · Source

Round 7 · 🔋 Element electron affinity · Finale

Name a chemical element closest to 2.1 eV.

Target 2.1 eV

Best answer

Sulfur

2.077 eV · 96 points · Source

Also close

Platinum

2.128 eV · 96 points · Source

Also close

Selenium

2.021 eV · 88 points · Source

Also close

Tellurium

1.971 eV · 81 points · Source

All puzzles Play today’s Plain